Document:

Exhibit 4.2

                                                                  Execution Copy

                          REGISTRATION RIGHTS AGREEMENT

     This Registration Rights Agreement (the "Agreement") is made and entered
into as of this 15th day of September, 2004 by and among World Heart
Corporation, a corporation incorporated under the laws of the Province of
Ontario, Canada (the "Company"), the "Investors" named in that certain Purchase
Agreement by and among the Company and the Investors (the "Purchase Agreement"),
and each Subscriber that has executed a subscription agreement (each a
"Subscription Agreement") in connection with the agency agreement between the
Company and Research Capital Corporation (the "Agency Agreement").

     The parties hereby agree as follows:

     1. Certain Definitions.

     As used in this Agreement, the following terms shall have the following
meanings:

     "Affiliate" means, with respect to any person, any other person which
directly or indirectly controls, is controlled by, or is under common control
with, such person.

     "Agent's Shares" means the shares of Common Stock issuable to the US Agent
as part of its compensation pursuant to the terms of an engagement letter dated
August 26, 2004 between the Company and the US Agent.

     "Agent's Warrants" means the Agent's Warrants issued to the Canadian Agent
as part of its compensation pursuant to the terms of an agency agreement dated
September 15, 2004 between the Company and the Canadian Agent.

     "Agent's Warrant Shares" means the shares of Common Stock issuable upon the
exercise of the Agent's Warrants.

     "Business Day" means a day, other than a Saturday or Sunday, on which banks
in New York City and Ottawa, Ontario are open for the general transaction of
business.

     "Canadian Agent" means Research Capital Corporation.

     "Common Stock" shall mean the Company's Common Shares, and any securities
into which such shares may hereinafter be reclassified.

     "Debentures" shall mean convertible debentures issued by the Company
pursuant to the Purchase Agreement or the Agency Agreement.

     "Debenture Shares" shall mean the shares of Common Stock issuable upon the
conversion of the Debentures.

     "Domestication Event" shall have the meaning ascribed thereto in Section
2(c)(ii) hereof.
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     "Effective Date" shall mean the date a Registration Statement is initially
declared effective by the SEC.

     "Effectiveness Deadline" shall have the meaning ascribed thereto in Section
2(c)(i) hereof.

     "Interest" shall mean the interest at the rate of 3% per annum (accrued but
not compounded) calculated on the outstanding principal amount of the
Debentures.

     "Interest Shares" shall mean shares of Common Stock issuable upon the
conversion of the Interest under the terms and conditions set forth in the
Debentures.

     "Investors" shall mean the Investors identified in the Purchase Agreement
and any Affiliate or permitted transferee of any Investor who is a subsequent
holder of any Warrants or Registrable Securities.

     "Prospectus" shall mean the prospectus included in any Registration
Statement, as amended or supplemented by any prospectus supplement, with respect
to the terms of the offering of any portion of the Registrable Securities
covered by such Registration Statement and by all other amendments and
supplements to the prospectus, including post-effective amendments and all
material incorporated by reference in such prospectus.

     "Purchasers" shall mean the Investors, the Subscribers, US Agent and
Canadian Agent.

     "Register," "registered" and "registration" refer to a registration made by
preparing and filing a Registration Statement or similar document in compliance
with the 1933 Act (as defined below), and the declaration or ordering of
effectiveness of such Registration Statement or document.

     "Registrable Securities" shall mean (i) the Debenture Shares, (ii) the
Interest Shares, (iii) the Warrant Shares (iv) the Agent's Shares, (v) the
Agent's Warrant Shares and (vi) any other securities issued or issuable with
respect to or in exchange for Registrable Securities; provided, that, a security
shall cease to be a Registrable Security upon (A) sale pursuant to a
Registration Statement or Rule 144 under the 1933 Act, (B) such security
becoming eligible for sale by the Purchasers pursuant to Rule 144(k) or (C) sale
through the facilities of the Toronto Stock Exchange.

     "Registration Statement" shall mean any registration statement of the
Company filed under the 1933 Act that covers the resale of any of the
Registrable Securities pursuant to the provisions of this Agreement, amendments
and supplements to such Registration Statement, including post-effective
amendments, all exhibits and all material incorporated by reference in such
Registration Statement.

     "Required Purchasers" means any Purchaser beneficially owning 20% or more
of the Registrable Securities and Purchasers holding a majority of the
Registrable Securities not including the US Agent and the Canadian Agent.

     "SEC" means the U.S. Securities and Exchange Commission.
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                                                                             -3-

     "Subscribers" shall mean the Subscribers identified in the Subscription
Agreements and any Affiliate or permitted transferee of any Subscriber who is a
subsequent holder of any Debenture, Warrant or Registrable Securities.

     "US Agent" means Roth Capital Partners.

     "Warrants" means the warrants to purchase shares of Common Stock (i) issued
to the Investors pursuant to the Purchase Agreement, the form of which is
attached to the Purchase Agreement as Exhibit A and (ii) issued to the
Subscribers pursuant to the Subscription Agreements.

     "Warrant Shares" means the shares of Common Stock issuable upon the
exercise of the Warrants.

     "1933 Act" means the Securities Act of 1933, as amended, and the rules and
regulations promulgated thereunder.

     "1934 Act" means the Securities Exchange Act of 1934, as amended, and the
rules and regulations promulgated thereunder.

     2. Registration.

               (a) Registration Statements.

               (i) Promptly following the closing of the purchase and sale of
the securities contemplated by the Purchase Agreement and the Subscription
Agreements (the "Closing Date") but no later than sixty (60) days after the
Closing Date (the "Filing Deadline"), the Company shall prepare and file with
the SEC one Registration Statement on Form F-3 (or, if Form F-3 is not then
available to the Company, on such form of registration statement as is then
available to effect a registration for resale of the Registrable Securities),
covering the resale of the Registrable Securities in an amount at least equal to
the aggregate of the Debenture Shares, the Warrant Shares, the Agent's Shares
and the Agent's Warrant Shares and the maximum amount of Interest Shares
issuable under the Debentures. Such Registration Statement shall include the
plan of distribution attached hereto as Exhibit A, subject to such modifications
as may be appropriate or necessary to respond to future interpretations or
comments of the SEC staff. Such Registration Statement also shall cover, to the
extent allowable under the 1933 Act and the rules promulgated thereunder
(including Rule 416), such indeterminate number of additional shares of Common
Stock resulting from stock splits, stock dividends or similar transactions with
respect to the Registrable Securities. The Company shall use its reasonable best
efforts to obtain from each person who now has piggyback registration rights a
waiver of those rights with respect to the Registration Statement. The
Registration Statement (and each amendment or supplement thereto, and each
request for acceleration of effectiveness thereof) shall be provided in
accordance with Section 3(c) to the Purchasers and their counsel prior to its
filing or other submission. If a Registration Statement covering the Registrable
Securities is not filed with the SEC on or prior to the Filing Deadline, the
Company will make pro rata payments to each Purchaser except the US Agent and
Canadian Agent, as liquidated damages and not as a penalty, in an amount equal
to 1.5% of the aggregate amount invested by such Purchaser for each 30-day
period or pro rata for any portion thereof following the date by which such
Registration
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Statement should have been filed for which no Registration Statement is filed
with respect to the Registrable Securities. Such payments shall be in partial
compensation to the Purchasers other than the US Agent and the Canadian Agent,
and shall not constitute such Purchasers' exclusive remedy for such events. Such
payments shall be made to such Purchasers in cash.

               (b) Expenses. The Company will pay all expenses associated with
each registration, including filing and printing fees, counsel and accounting
fees and expenses, costs associated with clearing the Registrable Securities for
sale under applicable state securities laws, listing fees, fees and expenses of
one counsel to the Purchasers and the Purchasers' reasonable expenses in
connection with the registration, but excluding discounts, commissions, fees of
underwriters, selling brokers, dealer managers or similar securities industry
professionals with respect to the Registrable Securities being sold.

               (c) Effectiveness.

               (i) The Company shall use commercially reasonable efforts to have
the Registration Statement declared effective as soon as practicable. The
Company shall notify the Purchasers by facsimile or e-mail as promptly as
practicable, and in any event, within twenty-four (24) hours, after any
Registration Statement is declared effective and shall simultaneously provide
the Purchasers with copies of any related Prospectus to be used in connection
with the sale or other disposition of the securities covered thereby. If (A) a
Registration Statement covering the Registrable Securities is not declared
effective by the SEC within one hundred and eighty (180) days after the Closing
Date (the "Effectiveness Deadline") (subject to extension as provided in clause
(ii) below), or (B) after a Registration Statement has been declared effective
by the SEC, sales cannot be made pursuant to such Registration Statement for any
reason (including without limitation by reason of a stop order, or the Company's
failure to update the Registration Statement), but excluding the inability of
any Purchaser to sell the Registrable Securities covered thereby due to market
conditions and except as excused pursuant to subparagraph (ii) below, then the
Company will make pro rata payments to each Purchaser except the US Agent and
the Canadian Agent, as liquidated damages and not as a penalty, in an amount
equal to 1.5% of the aggregate amount invested by such Purchaser, for each
30-day period or pro rata for any portion thereof following the date by which
such Registration Statement should have been effective (the "Blackout Period");
provided, however, that such liquidated damages shall accrue on any Registrable
Securities disposed of through the facilities of the TSX, if at all, only
through the date of such disposition. Such payments shall be in partial
compensation to the Purchasers other than the US Agent and the Canadian Agent,
and shall not constitute such Purchasers' exclusive remedy for such events. The
amounts payable as liquidated damages pursuant to this paragraph shall be paid
monthly within three (3) Business Days of the last day of each month following
the commencement of the Blackout Period until the termination of the Blackout
Period. Such payments shall be made to such Purchasers in cash.

               (ii) In the event that prior to the Effective Date of the
Registration Statement, (A) the Company ceases to be a "foreign private issuer"
as defined in Rule 405 of Regulation C promulgated under the 1933 Act (a
"Domestication Event") and (B) as a result of such Domestication Event the
Company must convert the Registration Statement into a registration statement on
Form S-3 (or any other registration form then applicable to the Company as a
result of the Domestication Event), the Company shall promptly (and in no event
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more than 15 days after the Domestication Event) prepare and file with the SEC
an amendment to the Registration Statement to effect such conversion. If a
Domestication Event occurs within thirty days of the Effectiveness Deadline, the
Effectiveness Deadline shall be extended for the number of days (not to exceed
15 days) elapsed in the period commencing on and including the date of the
Domestication Event and ending on but excluding the date that the Company files
an amendment to the Registration Statement effecting the conversion.

               (iii) No more than twice in any twelve (12) month period for an
aggregate of not more than thirty (30) days , the Company may delay the
disclosure of material non-public information concerning the Company, by
suspending the use of any Prospectus included in any registration contemplated
by this Section containing such information, the disclosure of which at the time
is not, in the good faith opinion of the Company, in the best interests of the
Company (an "Allowed Delay"); provided, that the Company shall promptly (a)
notify the Purchasers in writing of the existence of (but in no event, without
the prior written consent of a Purchaser, shall the Company disclose to such
Purchaser any of the facts or circumstances regarding) material non-public
information giving rise to an Allowed Delay, and (b) advise the Purchasers in
writing to cease all sales under the Registration Statement until the end of the
Allowed Delay.

               (d) Underwritten Offering. If any offering pursuant to a
Registration Statement pursuant to Section 2(a) hereof involves an underwritten
offering, the Company shall have the right to select an investment banker and
manager to administer the offering, which investment banker or manager shall be
reasonably satisfactory to the Required Purchasers.

     3. Company Obligations. The Company will use commercially reasonable
efforts to effect the registration of the Registrable Securities in accordance
with the terms hereof, and pursuant thereto the Company will, as expeditiously
as possible:

               (a) use commercially reasonable efforts to cause such
Registration Statement to become effective and to remain continuously effective
for a period that will terminate upon the earlier of (i) the date on which all
Registrable Securities covered by such Registration Statement as amended from
time to time, have been sold, and (ii) the date on which all Registrable
Securities covered by such Registration Statement may be sold pursuant to Rule
144(k);

               (b) prepare and file with the SEC such amendments and
post-effective amendments to the Registration Statement and the Prospectus as
may be necessary to keep the Registration Statement effective for the period
specified in Section 3(a) and to comply with the provisions of the 1933 Act and
the 1934 Act with respect to the distribution of all of the Registrable
Securities covered thereby;

               (c) provide copies to and permit counsel designated by the
Purchasers to review each Registration Statement and all amendments and
supplements thereto no fewer than three (3) Business Days prior to their filing
with the SEC and not file any document to which such counsel reasonably objects;
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               (d) furnish to the Purchasers and their legal counsel (i)
promptly after the same is prepared and publicly distributed, filed with the
SEC, or received by the Company (but not later than two (2) Business Days after
the filing date, receipt date or sending date, as the case may be) one (1) copy
of any Registration Statement and any amendment thereto, each preliminary
prospectus and Prospectus and each amendment or supplement thereto, and each
letter written by or on behalf of the Company to the SEC or the staff of the
SEC, and each item of correspondence from the SEC or the staff of the SEC, in
each case relating to such Registration Statement (other than any portion of any
thereof which contains information for which the Company has sought confidential
treatment), and (ii) such number of copies of a Prospectus, including a
preliminary prospectus, and all amendments and supplements thereto and such
other documents as each Purchaser may reasonably request in order to facilitate
the disposition of the Registrable Securities owned by such Purchaser that are
covered by the related Registration Statement;

               (e) in the event the Company selects an underwriter for the
offering, the Company shall enter into and perform its reasonable obligations
under an underwriting agreement, in usual and customary form, including, without
limitation, customary indemnification and contribution obligations, with the
underwriter of such offering;

               (f) if required by the underwriter, or if any Purchaser is
described in the Registration Statement as an underwriter, the Company shall
furnish, on the effective date of the Registration Statement (except with
respect to clause (i) below) and on the date that Registrable Securities are
delivered to an underwriter, if any, for sale in connection with the
Registration Statement (including any Purchaser deemed to be an underwriter),
(i) (A) in the case of an underwritten offering, an opinion, dated as of the
closing date of the sale of Registrable Securities to the underwriters, from
independent legal counsel representing the Company for purposes of such
Registration Statement, in form, scope and substance as is customarily given in
an underwritten public offering, addressed to the underwriters and the
Purchasers participating in such underwritten offering or (B) in the case of an
"at the market" offering, an opinion, dated as of or promptly after the
effective date of the Registration Statement to the Purchasers, from independent
legal counsel representing the Company for purposes of such Registration
Statement, in form, scope and substance as is customarily given in a public
offering, addressed to the Purchasers, and (ii) a letter, dated as of the
effective date of such Registration Statement and confirmed as of the applicable
dates described above, from the Company's independent certified public
accountants in form and substance as is customarily given by independent
certified public accountants to underwriters in an underwritten public offering,
addressed to the underwriters (including any Purchaser deemed to be an
underwriter);

               (g) use commercially reasonable efforts to (i) prevent the
issuance of any stop order or other suspension of effectiveness and, (ii) if
such order is issued, obtain the withdrawal of any such order at the earliest
possible moment;

               (h) prior to any public offering of Registrable Securities, use
commercially reasonable efforts to register or qualify or cooperate with the
Purchasers and their counsel in connection with the registration or
qualification of such Registrable Securities for offer and sale under the
securities or blue sky laws of such jurisdictions requested by the Purchasers
and do any and all other commercially reasonable acts or things necessary or
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advisable to enable the distribution in such jurisdictions of the Registrable
Securities covered by the Registration Statement; provided, however, that the
Company shall not be required in connection therewith or as a condition thereto
to (i) qualify to do business in any jurisdiction where it would not otherwise
be required to qualify but for this Section 3(h), (ii) subject itself to general
taxation in any jurisdiction where it would not otherwise be so subject but for
this Section 3(h), or (iii) file a general consent to service of process in any
such jurisdiction;

               (i) use commercially reasonable efforts to cause all Registrable
Securities covered by a Registration Statement to be listed on each securities
exchange, interdealer quotation system or other market on which similar
securities issued by the Company are then listed;

               (j) immediately notify the Purchasers, at any time when a
Prospectus relating to Registrable Securities is required to be delivered under
the 1933 Act, upon discovery that, or upon the happening of any event as a
result of which, the Prospectus included in a Registration Statement, as then in
effect, includes an untrue statement of a material fact or omits to state any
material fact required to be stated therein or necessary to make the statements
therein not misleading in light of the circumstances then existing, and at the
request of any such holder, promptly prepare and furnish to such holder a
reasonable number of copies of a supplement to or an amendment of such
Prospectus as may be necessary so that, as thereafter delivered to the
purchasers of such Registrable Securities, such Prospectus shall not include an
untrue statement of a material fact or omit to state a material fact required to
be stated therein or necessary to make the statements therein not misleading in
light of the circumstances then existing; and

               (k) otherwise use commercially reasonable efforts to comply with
all applicable rules and regulations of the SEC under the 1933 Act and the 1934
Act, take such other actions as may be reasonably necessary to facilitate the
registration of the Registrable Securities hereunder; and make available to its
security holders, as soon as reasonably practicable, but not later than the
Availability Date (as defined below), an earnings statement covering a period of
at least twelve (12) months, beginning after the effective date of each
Registration Statement, which earnings statement shall satisfy the provisions of
Section 11(a) of the 1933 Act, including Rule 158 promulgated thereunder (for
the purpose of this subsection 3(k), "Availability Date" means the 45th day
following the end of the fourth fiscal quarter that includes the effective date
of such Registration Statement, except that, if such fourth fiscal quarter is
the last quarter of the Company's fiscal year, "Availability Date" means the
90th day after the end of such fourth fiscal quarter).

               (l) with a view to making available to the Purchasers the
benefits of Rule 144 (or its successor rule) and any other rule or regulation of
the SEC that may at any time permit the Purchasers to sell shares of Common
Stock to the public without registration, the Company covenants and agrees to:
(i) make and keep public information available, as those terms are understood
and defined in Rule 144, until the earlier of (A) six months after such date as
all of the Registrable Securities may be resold pursuant to Rule 144(k) or any
other rule of similar effect or (B) such date as all of the Registrable
Securities shall have been resold; (ii) file with the SEC in a timely manner all
reports and other documents required of the Company under the 1934 Act; and
(iii) furnish to each Purchaser upon request, as long as such Purchaser owns any
Registrable Securities, (A) a written statement by the Company that it has
complied with the
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reporting requirements of the 1934 Act, (B) a copy of the Company's most recent
Annual Report on Form 40-F (or such other form then available to the Company),
and (C) such other information as may be reasonably requested in order to avail
such Purchaser of any rule or regulation of the SEC that permits the selling of
any such Registrable Securities without registration.

     4. Due Diligence Review; Information. The Company shall make available,
during normal business hours, for inspection and review by the Purchasers,
advisors to and representatives of the Purchasers (who may or may not be
affiliated with the Purchasers and who are reasonably acceptable to the
Company), any underwriter participating in any disposition of shares of Common
Stock on behalf of the Purchasers pursuant to a Registration Statement or
amendments or supplements thereto or any blue sky, NASD or other filing, all
financial and other records, all SEC Filings (as defined in the Purchase
Agreement) and other filings with the SEC, and all other corporate documents and
properties of the Company as may be reasonably necessary for the purpose of such
review, and cause the Company's officers, directors and employees, within a
reasonable time period, to supply all such information reasonably requested by
the Purchasers or any such representative, advisor or underwriter in connection
with such Registration Statement (including, without limitation, in response to
all questions and other inquiries reasonably made or submitted by any of them),
prior to and from time to time after the filing and effectiveness of the
Registration Statement for the sole purpose of enabling the Purchasers and such
representatives, advisors and underwriters and their respective accountants and
attorneys to conduct initial and ongoing due diligence with respect to the
Company and the accuracy of such Registration Statement.

     The Company shall not disclose material nonpublic information to the
Purchasers, or to advisors to or representatives of the Purchasers, unless prior
to disclosure of such information the Company identifies such information as
being material nonpublic information and provides the Purchasers, such advisors
and representatives with the opportunity to accept or refuse to accept such
material nonpublic information for review and any Purchaser wishing to obtain
such information enters into an appropriate confidentiality agreement with the
Company with respect thereto.

     5. Obligations of the Purchasers.

               (a) Each Purchaser shall furnish in writing to the Company such
information regarding itself, the Registrable Securities held by it and the
intended method of disposition of the Registrable Securities held by it, as
shall be reasonably required to effect the registration of such Registrable
Securities and shall execute such documents in connection with such registration
as the Company may reasonably request. At least five (5) Business Days prior to
the first anticipated filing date of any Registration Statement, the Company
shall notify each Purchaser of the information the Company requires from such
Purchaser if such Purchaser elects to have any of the Registrable Securities
included in the Registration Statement. A Purchaser shall provide such
information to the Company at least two (2) Business Days prior to the first
anticipated filing date of such Registration Statement if such Purchaser elects
to have any of the Registrable Securities included in the Registration
Statement.
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               (b) Each Purchaser, by its acceptance of the Registrable
Securities agrees to cooperate with the Company as reasonably requested by the
Company in connection with the preparation and filing of a Registration
Statement hereunder, unless such Purchaser has notified the Company in writing
of its election to exclude all of its Registrable Securities from such
Registration Statement.

               (c) In the event the Company, at the request of the Purchasers,
determines to engage the services of an underwriter, such Purchaser agrees to
enter into and perform its obligations under an underwriting agreement, in usual
and customary form, including, without limitation, customary indemnification and
contribution obligations, with the managing underwriter of such offering and
take such other actions as are reasonably required in order to expedite or
facilitate the dispositions of the Registrable Securities.

               (d) Each Purchaser agrees that, upon receipt of any notice from
the Company of either (i) the commencement of an Allowed Delay pursuant to
Section 2(c)(ii) or (ii) the happening of an event pursuant to Section 3(j)
hereof, such Purchaser will immediately discontinue disposition of Registrable
Securities pursuant to the Registration Statement covering such Registrable
Securities, until the Purchaser's receipt of the copies of the supplemented or
amended prospectus filed with the SEC and declared effective and, if so directed
by the Company, the Purchaser shall deliver to the Company (at the expense of
the Company) or destroy (and deliver to the Company a certificate of
destruction) all copies in the Purchaser's possession of the Prospectus covering
the Registrable Securities current at the time of receipt of such notice.

               (e) No Purchaser may participate in any third party underwritten
registration hereunder unless it (i) agrees to sell the Registrable Securities
on the basis provided in any underwriting arrangements in usual and customary
form entered into by the Company, (ii) completes and executes all
questionnaires, powers of attorney, indemnities, underwriting agreements and
other documents reasonably required under the terms of such underwriting
arrangements, and (iii) agrees to pay its pro rata share of all underwriting
discounts and commissions. Notwithstanding the foregoing, no Purchaser shall be
required to make any representations to such underwriter, other than those with
respect to itself and the Registrable Securities owned by it, including its
right to sell the Registrable Securities, and any indemnification in favor of
the underwriter by the Purchasers shall be several and not joint and limited in
the case of any Purchaser, to the proceeds received by such Purchaser from the
sale of its Registrable Securities. The scope of any such indemnification in
favor of an underwriter shall be limited to the same extent as the indemnity
provided in Section 6(b) hereof.

     6. Indemnification.

               (a) Indemnification by the Company. The Company will indemnify
and hold harmless each Purchaser and its officers, directors, members, employees
and agents, successors and assigns, and each other person, if any, who controls
such Purchaser within the meaning of the 1933 Act, against any losses, claims,
damages or liabilities, joint or several, to which they may become subject under
the 1933 Act or otherwise, insofar as such losses, claims, damages or
liabilities (or actions in respect thereof) arise out of or are based upon: (i)
any untrue statement or alleged untrue statement of any material fact contained
in any Registration
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                                                                            -10-

Statement, any preliminary prospectus or final prospectus
contained therein, or any amendment or supplement thereof; (ii) any blue sky
application or other document executed by the Company specifically for that
purpose or based upon written information furnished by the Company filed in any
state or other jurisdiction in order to qualify any or all of the Registrable
Securities under the securities laws thereof (any such application, document or
information herein called a "Blue Sky Application"); (iii) the omission or
alleged omission to state therein a material fact required to be stated therein
or necessary to make the statements therein not misleading; (iv) any violation
by the Company or its agents of any rule or regulation promulgated under the
1933 Act applicable to the Company or its agents and relating to action or
inaction required of the Company in connection with such registration; or (v)
any failure to register or qualify the Registrable Securities included in any
such Registration in any state where the Company or its agents has affirmatively
undertaken or agreed in writing that the Company will undertake such
registration or qualification on a Purchaser's behalf (the undertaking of any
underwriter chosen by the Company being attributed to the Company) and will
reimburse such Purchaser, and each such officer, director or member and each
such controlling person for any legal or other expenses reasonably incurred by
them in connection with investigating or defending any such loss, claim, damage,
liability or action; provided, however, that the Company will not be liable in
any such case if and to the extent that any such loss, claim, damage or
liability arises out of or is based upon an untrue statement or alleged untrue
statement or omission or alleged omission so made in conformity with information
furnished by such Purchaser or any such controlling person in writing
specifically for use in such Registration Statement or Prospectus.

               (b) Indemnification by the Purchasers. In connection with any
registration pursuant to the terms of this Agreement, each Purchaser will
furnish to the Company in writing such information as the Company reasonably
requests concerning the holders of Registrable Securities or the proposed manner
of distribution for use in connection with any Registration Statement or
Prospectus and agrees, severally but not jointly, to indemnify and hold
harmless, to the fullest extent permitted by law, the Company, its directors,
officers, employees, stockholders and each person who controls the Company
(within the meaning of the 1933 Act) against any losses, claims, damages,
liabilities and expense (including reasonable attorney fees) resulting from any
untrue statement of a material fact or any omission of a material fact required
to be stated in the Registration Statement or Prospectus or preliminary
prospectus or amendment or supplement thereto or necessary to make the
statements therein not misleading, to the extent, but only to the extent that
such untrue statement or omission is contained in any information furnished in
writing by such Purchaser to the Company specifically for inclusion in such
Registration Statement or Prospectus or amendment or supplement thereto. In no
event shall the liability of a Purchaser be greater in amount than the dollar
amount of the proceeds (net of all expense paid by such Purchaser in connection
with any claim relating to this Section 6 and the amount of any damages such
holder has otherwise been required to pay by reason of such untrue statement or
omission) received by such Purchaser upon the sale of the Registrable Securities
included in the Registration Statement giving rise to such indemnification
obligation.

               (c) Conduct of Indemnification Proceedings. Any person entitled
to indemnification hereunder shall (i) give prompt notice to the indemnifying
party of any claim with respect to which it seeks indemnification and (ii)
permit such indemnifying party to assume the defense of such claim with counsel
reasonably satisfactory to the indemnified party; provided that any person
entitled to indemnification hereunder shall have the right to employ
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                                                                            -11-

separate counsel and to participate in the defense of such claim, but the
fees and expenses of such counsel shall be at the expense of such person unless
(a) the indemnifying party has agreed to pay such fees or expenses, or (b) the
indemnifying party shall have failed to assume the defense of such claim and
employ counsel reasonably satisfactory to such person or (c) in the reasonable
judgment of any such person, based upon written advice of its counsel, a
conflict of interest exists between such person and the indemnifying party with
respect to such claims (in which case, if the person notifies the indemnifying
party in writing that such person elects to employ separate counsel at the
expense of the indemnifying party, the indemnifying party shall not have the
right to assume the defense of such claim on behalf of such person); and
provided, further, that the failure of any indemnified party to give notice as
provided herein shall not relieve the indemnifying party of its obligations
hereunder, except to the extent that such failure to give notice shall
materially adversely affect the indemnifying party in the defense of any such
claim or litigation. It is understood that the indemnifying party shall not, in
connection with any proceeding in the same jurisdiction, be liable for fees or
expenses of more than one separate firm of attorneys at any time for all such
indemnified parties. No indemnifying party will, except with the consent of the
indemnified party, consent to entry of any judgment or enter into any settlement
that does not include as an unconditional term thereof the giving by the
claimant or plaintiff to such indemnified party of a release from all liability
in respect of such claim or litigation.

               (d) Contribution. If for any reason the indemnification provided
for in the preceding paragraphs (a) and (b) is unavailable to an indemnified
party or insufficient to hold it harmless, other than as expressly specified
therein, then the indemnifying party shall contribute to the amount paid or
payable by the indemnified party as a result of such loss, claim, damage or
liability in such proportion as is appropriate to reflect the relative fault of
the indemnified party and the indemnifying party, as well as any other relevant
equitable considerations. No person guilty of fraudulent misrepresentation
within the meaning of Section 11(f) of the 1933 Act shall be entitled to
contribution from any person not guilty of such fraudulent misrepresentation. In
no event shall the contribution obligation of a holder of Registrable Securities
be greater in amount than the dollar amount of the proceeds (net of all expenses
paid by such holder in connection with any claim relating to this Section 6 and
the amount of any damages such holder has otherwise been required to pay by
reason of such untrue or alleged untrue statement or omission or alleged
omission) received by it upon the sale of the Registrable Securities giving rise
to such contribution obligation.

     7. Miscellaneous.

               (a) Amendments and Waivers. This Agreement may be amended only by
a writing signed by the Company and the Required Purchasers. The Company may
take any action herein prohibited, or omit to perform any act herein required to
be performed by it, only if the Company shall have obtained the written consent
to such amendment, action or omission to act, of the Required Purchasers.

               (b) Notices. All notices and other communications provided for or
permitted hereunder shall be made (i) as set forth in Section 9.4 of the
Purchase Agreement and (ii) to each Subscriber at the address listed on Page 1
of its respective Subscription Agreement.
<PAGE>
                                                                            -12-

               (c) Assignments and Transfers by Purchasers. The provisions of
this Agreement shall be binding upon and inure to the benefit of the Purchasers
and their respective successors and assigns. A Purchaser except the US Agent or
Canadian Agent may transfer or assign, in whole or from time to time in part, to
one or more persons its rights hereunder in connection with the transfer of
Registrable Securities by such Purchaser to such person, provided that such
Purchaser complies with all laws applicable thereto and provides written notice
of assignment to the Company promptly after such assignment is effected.

               (d) Assignments and Transfers by the Company. This Agreement may
not be assigned by the Company (whether by operation of law or otherwise)
without the prior written consent of the Required Purchasers, provided, however,
that the Company may assign its rights and delegate its duties hereunder to any
surviving or successor corporation in connection with a merger or consolidation
of the Company with another corporation, or a sale, transfer or other
disposition of all or substantially all of the Company's assets to another
corporation, without the prior written consent of the Required Purchasers, after
notice duly given by the Company to each Purchaser.

               (e) Benefits of the Agreement. The terms and conditions of this
Agreement shall inure to the benefit of and be binding upon the respective
permitted successors and assigns of the parties. Nothing in this Agreement,
express or implied, is intended to confer upon any party other than the parties
hereto or their respective successors and assigns any rights, remedies,
obligations, or liabilities under or by reason of this Agreement, except as
expressly provided in this Agreement.

               (f) Counterparts; Faxes. This Agreement may be executed in two or
more counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument. This Agreement may also
be executed via facsimile, which shall be deemed an original.

               (g) Titles and Subtitles. The titles and subtitles used in this
Agreement are used for convenience only and are not to be considered in
construing or interpreting this Agreement.

               (h) Severability. Any provision of this Agreement that is
prohibited or unenforceable in any jurisdiction shall, as to such jurisdiction,
be ineffective to the extent of such prohibition or unenforceability without
invalidating the remaining provisions hereof but shall be interpreted as if it
were written so as to be enforceable to the maximum extent permitted by
applicable law, and any such prohibition or unenforceability in any jurisdiction
shall not invalidate or render unenforceable such provision in any other
jurisdiction. To the extent permitted by applicable law, the parties hereby
waive any provision of law which renders any provisions hereof prohibited or
unenforceable in any respect.

               (i) Further Assurances. The parties shall execute and deliver all
such further instruments and documents and take all such other actions as may
reasonably be required to carry out the transactions contemplated hereby and to
evidence the fulfillment of the agreements herein contained.
<PAGE>
                                                                            -13-

               (j) Entire Agreement. This Agreement is intended by the parties
as a final expression of their agreement and intended to be a complete and
exclusive statement of the agreement and understanding of the parties hereto in
respect of the subject matter contained herein. This Agreement supersedes all
prior agreements and understandings between the parties with respect to such
subject matter.

               (k) Governing Law; Consent to Jurisdiction. This Agreement shall
be governed by, and construed in accordance with, the internal laws of the State
of New York without regard to the choice of law principles thereof. Each of the
parties hereto irrevocably submits to the exclusive jurisdiction of the courts
of the State of New York located in New York County and the United States
District Court for the Southern District of New York for the purpose of any
suit, action, proceeding or judgment relating to or arising out of this
Agreement and the transactions contemplated hereby. Service of process in
connection with any such suit, action or proceeding may be served on each party
hereto anywhere in the world by the same methods as are specified for the giving
of notices under this Agreement. Each of the parties hereto irrevocably consents
to the jurisdiction of any such court in any such suit, action or proceeding and
to the laying of venue in such court. Each party hereto irrevocably waives any
objection to the laying of venue of any such suit, action or proceeding brought
in such courts and irrevocably waives any claim that any such suit, action or
proceeding brought in any such court has been brought in an inconvenient forum.
<PAGE>
                                                                            -14-

IN WITNESS WHEREOF, the parties have executed this Agreement or caused their
duly authorized officers to execute this Agreement as of the date first above
written.

The Company:                                WORLD HEART CORPORATION

                                            By:
                                                -------------------------
                                            Name:
                                            Title:

The Investor:

                                            By:
                                                -------------------------
                                            Name:
                                            Title:
<PAGE>
                                                                            -15-

                                                                       Exhibit A

                              Plan of Distribution

         The selling stockholders, which as used herein includes donees,
pledgees, transferees or other successors-in-interest selling shares of common
stock or interests in shares of common stock received after the date of this
prospectus from a selling stockholder as a gift, pledge, partnership
distribution or other transfer, may, from time to time, sell, transfer or
otherwise dispose of any or all of their shares of common stock or interests in
shares of common stock on any stock exchange, market or trading facility on
which the shares are traded or in private transactions. These dispositions may
be at fixed prices, at prevailing market prices at the time of sale, at prices
related to the prevailing market price, at varying prices determined at the time
of sale, or at negotiated prices.

     The selling stockholders may use any one or more of the following methods
when disposing of shares or interests therein:

     - ordinary brokerage transactions and transactions in which the
broker-dealer solicits purchasers;

     - block trades in which the broker-dealer will attempt to sell the shares
as agent, but may position and resell a portion of the block as principal to
facilitate the transaction;

     - purchases by a broker-dealer as principal and resale by the broker-dealer
for its account;

     - an exchange distribution in accordance with the rules of the applicable
exchange;

     - privately negotiated transactions;

     - short sales effected after the date the registration statement of which
this Prospectus is a part is declared effective by the SEC;

     - through the writing or settlement of options or other hedging
transactions, whether through an options exchange or otherwise;

     - broker-dealers may agree with the selling stockholders to sell a
specified number of such shares at a stipulated price per share;

     - a combination of any such methods of sale; and

     - any other method permitted pursuant to applicable law.

     The selling stockholders may, from time to time, pledge or grant a security
interest in some or all of the shares of common stock owned by them and, if they
default in the performance of their secured obligations, the pledgees or secured
parties may offer and sell the shares of common stock, from time to time, under
this prospectus, or under an amendment to this
<PAGE>
                                                                            -16-

prospectus under Rule 424(b)(3) or other applicable provision of the Securities
Act amending the list of selling stockholders to include the pledgee, transferee
or other successors in interest as selling stockholders under this prospectus.
The selling stockholders also may transfer the shares of common stock in other
circumstances, in which case the transferees, pledgees or other successors in
interest will be the selling beneficial owners for purposes of this prospectus.

     In connection with the sale of our common stock or interests therein, the
selling stockholders may enter into hedging transactions with broker-dealers or
other financial institutions, which may in turn engage in short sales of the
common stock in the course of hedging the positions they assume. The selling
stockholders may also sell shares of our common stock short and deliver these
securities to close out their short positions, or loan or pledge the common
stock to broker-dealers that in turn may sell these securities. The selling
stockholders may also enter into option or other transactions with
broker-dealers or other financial institutions or the creation of one or more
derivative securities which require the delivery to such broker-dealer or other
financial institution of shares offered by this prospectus, which shares such
broker-dealer or other financial institution may resell pursuant to this
prospectus (as supplemented or amended to reflect such transaction).

     The aggregate proceeds to the selling stockholders from the sale of the
common stock offered by them will be the purchase price of the common stock less
discounts or commissions, if any. Each of the selling stockholders reserves the
right to accept and, together with their agents from time to time, to reject, in
whole or in part, any proposed purchase of common stock to be made directly or
through agents. We will not receive any of the proceeds from this offering. Upon
any exercise of the warrants by payment of cash, however, we will receive the
exercise price of the warrants.

     The selling stockholders also may resell all or a portion of the shares in
open market transactions in reliance upon Rule 144 under the Securities Act of
1933, provided that they meet the criteria and conform to the requirements of
that rule.

     The selling stockholders and any underwriters, broker-dealers or agents
that participate in the sale of the common stock or interests therein may be
"underwriters" within the meaning of Section 2(11) of the Securities Act. Any
discounts, commissions, concessions or profit they earn on any resale of the
shares may be underwriting discounts and commissions under the Securities Act.
Selling stockholders who are "underwriters" within the meaning of Section 2(11)
of the Securities Act will be subject to the prospectus delivery requirements of
the Securities Act.

     To the extent required, the shares of our common stock to be sold, the
names of the selling stockholders, the respective purchase prices and public
offering prices, the names of any agents, dealer or underwriter, any applicable
commissions or discounts with respect to a particular offer will be set forth in
an accompanying prospectus supplement or, if appropriate, a post-effective
amendment to the registration statement that includes this prospectus.

     In order to comply with the securities laws of some states, if applicable,
the common stock may be sold in these jurisdictions only through registered or
licensed brokers or dealers. In addition, in some states the common stock may
not be sold unless it has been registered or
<PAGE>
                                                                            -17-

qualified for sale or an exemption from registration or qualification
requirements is available and is complied with.

     We have advised the selling stockholders that the anti-manipulation rules
of Regulation M under the Exchange Act may apply to sales of shares in the
market and to the activities of the selling stockholders and their affiliates.
In addition, we will make copies of this prospectus (as it may be supplemented
or amended from time to time) available to the selling stockholders for the
purpose of satisfying the prospectus delivery requirements of the Securities
Act. The selling stockholders may indemnify any broker-dealer that participates
in transactions involving the sale of the shares against certain liabilities,
including liabilities arising under the Securities Act.

     We have agreed to indemnify the selling stockholders against liabilities,
including liabilities under the Securities Act and state securities laws,
relating to the registration of the shares offered by this prospectus.

     We have agreed with the selling stockholders to keep the registration
statement of which this prospectus constitutes a part effective until the
earlier of (1) such time as all of the shares covered by this prospectus have
been disposed of pursuant to and in accordance with the registration statement
or (2) the date on which the shares may be sold pursuant to Rule 144(k) of the
Securities Act.Exhibit 4.3

                             WORLD HEART CORPORATION

                                       and

                            CIBC MELLON TRUST COMPANY

--------------------------------------------------------------------------------

                                WARRANT INDENTURE

                     Providing for the Creation and Issue of
                                    Warrants

--------------------------------------------------------------------------------

                         Dated as of September 15, 2004
<PAGE>
                                WARRANT INDENTURE

     THIS INDENTURE dated as of September 15, 2004

B E T W E E N:

              WORLD HEART CORPORATION, a corporation incorporated under the
              laws of the Province of Ontario ("WorldHeart" or "the
              Corporation")

                                     - and -

              CIBC MELLON TRUST COMPANY, a trust company existing under the
              laws of Canada (the "Warrant Agent")

     WHEREAS:

A.   WorldHeart wishes to raise money for funding ongoing operations including
     the RELIANT Trial, manufacturing of the Novacor LVAS products, sales and
     marketing efforts, research and development, restructuring costs and
     general corporate purposes and proposes to issue Debentures and Warrants;

B.   The offering is US$13,318,750 (the "Offering") unsecured convertible
     debentures and common share purchase warrants of the Corporation at a rate
     of one warrant for each US$1.25 principal amount of Debentures.

C.   WorldHeart is duly authorized to create and issue the Warrants as herein
     provided and complete the transactions contemplated herein;

D.   All things necessary have been or will be done and performed to make the
     Warrant Certificates, when certified by the Warrant Agent and issued and
     delivered as herein provided, legal, valid and binding on WorldHeart with
     the benefits of and subject to the terms of this Indenture; and

E.   The Warrant Agent has agreed to enter into this Indenture and to hold all
     rights, interests and benefits contained herein for and on behalf of those
     persons who from time to time become holders of Warrants issued pursuant to
     this Indenture;

F.   The foregoing statements of fact are made by WorldHeart and not the Warrant
     Agent;

     NOW THEREFORE THIS INDENTURE WITNESSES that for good and valuable
consideration mutually given, the receipt and sufficiency of which are, by each
of WorldHeart and the Warrant Agent, hereby acknowledged, WorldHeart hereby
appoints the Warrant Agent as trustee for the Warrantholders, to hold all
rights, interests and benefits contained herein for and on behalf of those
persons who from time to time become holders of Warrants issued pursuant to this
Indenture, and the parties hereby covenant, agree and declare as follows:
<PAGE>
                                      -2-

                                   ARTICLE 1

                                 INTERPRETATION

1.1  Definitions

     In this Indenture, unless there is something in the subject matter or
context inconsistent therewith:

(1)  "affiliate" shall have the meaning ascribed to such term in the Business
     Corporations Act (Ontario), as amended from time to time, and in the case
     of CIBC Mellon Trust Company shall be deemed to include CIBC Mellon Global
     Securities Company, Canadian Imperial Bank of Commerce, Mellon Bank N.A.
     and their affiliates;

(2)  "Agent's Warrants" means 193,800 warrants to be issued to Research Capital
     Corporation;

(3)  "Applicable Legislation" means such provisions of any statute of Canada, of
     a province or territory thereof, and of regulations under any such statute
     relating to corporate laws, securities laws and trust indentures or to the
     rights, duties and obligations of corporations and of warrant trustees
     under trust indentures, as are from time to time in force and applicable to
     this Indenture;

(4)  "business day" means any day that is not a Saturday, Sunday or statutory or
     civic holiday in Ontario or New York;

(5)  "Common Shares" means the common shares in the capital of WorldHeart,
     provided that in the event of any adjustment pursuant to Article 5, "Common
     Shares" will thereafter mean the shares or other securities or property
     resulting from such adjustment;

(6)  "counsel" means a barrister or solicitor or a firm of barristers and
     solicitors (who may be counsel for WorldHeart) acceptable to the Warrant
     Agent, acting reasonably;

(7)  "Current Market Price" as of a particular date (the "Valuation Date") shall
     mean the following: (a) if the Common Shares are then quoted on NASDAQ, the
     closing price of one Common Share on NASDAQ on the last Trading Day prior
     to the Valuation Date or, if no such closing price is available, the
     average of the high bid and the low asked price quoted on NASDAQ on the
     last trading day prior to the Valuation Date; (b) if the Common Shares are
     not quoted on NASDAQ and the Common Shares are then listed on the TSX, the
     closing price of one Common Share on the TSX on the last trading day prior
     to the Valuation Date; or (c) if the Common Shares are not then listed on
     the TSX or quoted on NASDAQ, the fair market value of one Common Share as
     of the Valuation Date, shall be determined in good faith by the directors
     of the Corporation. The directors of the Corporation shall respond
     promptly, in writing, to an inquiry by the Warrantholders as to the Current
     Market Price of a Common Share as determined by the directors of the
     Corporation.
<PAGE>
                                      -3-

(8)  "Debentures" means unsecured convertible debentures convertible into common
     shares at a rate of US$1.25 principal amount of debentures per Common Share
     for a period of 60 months from the Closing Date and bearing interest at the
     rate of 3% per annum.

(9)  "director" means a director of WorldHeart for the time being, and reference
     to action by the directors means action by the directors of WorldHeart as a
     board or, to the extent empowered, by a committee of the board, in each
     case by resolution duly passed;

(10) "Effective Date" means September 15, 2004, the date as of which this
     Indenture is effective;

(11) "Exercise Date" means, with respect to any Warrant exercised by the holder
     thereof, the day on which the Warrant is exercised in accordance with the
     provisions of Section 4.1;

(12) "Exercise Price" means the price per Common Share, being US$1.55 as at the
     Effective Date, unless such price shall have been adjusted under Article 5
     in which case it shall mean the adjusted price in effect at the applicable
     time;

(13) "Expiry Time" means 5:00 p.m. (Toronto time) on the date that is 60 months
     from the Effective Date;

(14) "Legend Date" means the date that is four months and one day from the
     Effective Date;

(15) "NASDAQ" means the The Nasdaq Stock Market, Inc.

(16) "person" means an individual, corporation, limited liability company,
     partnership, trustee or unincorporated organization, and words importing
     persons have a similar extended meaning;

(17) "Qualifying Jurisdictions" means Ontario, British Columbia and Luxembourg;

(18) "Regulatory Approval" in respect of any transaction or proposed transaction
     means all material approvals, rulings, authorizations, permissions,
     filings, consents, orders and sanctions (including the lapse without
     objection of a prescribed time under a statute, regulation, by-law, rule,
     or other legislative or regulatory requirement that states that a
     transaction may be implemented if a prescribed time lapses following the
     giving or filing of notice without an objection being made) required to be
     obtained from or made to any governmental authority having jurisdiction or
     authority over any of the parties to such transaction to permit the
     completion of such transaction;

(19) "this Warrant Indenture", "this Indenture", "hereto", "hereunder",
     "hereof", "herein", "hereby" and similar expressions mean or refer to this
     Warrant Indenture and any indenture, deed or instrument supplemental or
     ancillary hereto, and the expressions "Article", "Section", "Subsection"
     and "paragraph" followed by a number mean the specified Article, Section,
     Subsection or paragraph of this Warrant Indenture;
<PAGE>
                                      -4-

(20) "Trading Day" means a day during which the NASDAQ is open for trading and
     at least one board lot of the Common Shares has traded on the NASDAQ;

(21) "TSX" means the Toronto Stock Exchange;

(22) "U.S. Securities Act" means the United States Securities Act of 1933, as
     amended.

(23) "voting shares" of any corporation means shares of one or more classes or
     series of a class of shares in the capital of such corporation carrying
     voting rights under all circumstances (and not by reason of the happening
     of a contingency) sufficient if exercised to elect all of the directors of
     such corporation, provided that such shares will be deemed not to cease to
     be voting shares solely by reason of a right to vote for the election of
     one or more of the directors of such corporation accruing to shares of
     another class or series of a class of shares of such corporation by reason
     of the happening of a contingency;

(24) "Warrant Agent" means CIBC Mellon Trust Company and includes any successor
     or permitted assigns for the time being in the trusts created hereby;

(25) "Warrant Certificate" means a certificate evidencing one or more Warrants,
     substantially in the form set out in Schedule A;

(26) "Warrants" means the up to 10,655,000 Warrants of WorldHeart created and
     authorized for issue pursuant to Section 2.1 hereof, each Warrant entitling
     the holder thereof to acquire one Common Share, as may be adjusted, at the
     Exercise Price at any time prior to the Expiry Time;

(27) "Warrantholders" or "holders" means the persons for the time being entered
     in a register of holders described in Section 3.1 as holders of Warrants;

(28) "Warrantholders' Request" means an instrument, signed in one or more
     counterparts by Warrantholders who hold in the aggregate not less than 10%
     of the total number of Warrants outstanding for the time being, requesting
     the Warrant Agent to take some action or proceeding specified therein;

(29) "WorldHeart" or "Corporation" means World Heart Corporation, and includes
     any successor corporation to or of such party which shall have complied
     with the provisions Section 9.2;

(30) "WorldHeart's auditors" means PricewaterhouseCoopers LLP, the firm of
     chartered accountants duly appointed as auditors of WorldHeart for the time
     being or any other firm appointed to replace such firm; and

(31) "written order of WorldHeart", "written request of WorldHeart", "written
     consent of WorldHeart", "written direction of WorldHeart" and "certificate
     of WorldHeart" mean, respectively, a written order, request, consent,
     direction and certificate signed in the name of WorldHeart by any director
     or officer of WorldHeart or by any other
<PAGE>
                                      -5-

     individual to whom such signing authority is delegated by the directors
     from time to time, and may consist of one or more instruments so executed.

1.2  Meaning of Outstanding

     Each Warrant certified and delivered by the Warrant Agent under this
Indenture will be deemed to be outstanding until it is cancelled or delivered to
the Warrant Agent for cancellation as the case may be, or until the Warrants
have been exercised pursuant to the terms of this Indenture, provided that:

     (a)  when a new Warrant Certificate has been issued in substitution for a
          Warrant Certificate which has been mutilated, lost, stolen or
          destroyed, only one of such Warrant Certificates will be counted for
          the purposes of determining the number of Warrants outstanding; and

     (b)  for the purposes of any provision of this Indenture entitling holders
          of outstanding Warrants to vote, sign consents, requisitions or other
          instruments or take any other action under this Indenture, Warrants
          owned, directly or indirectly, legally or beneficially by WorldHeart
          or an affiliate of WorldHeart will be disregarded except that:

          (i)  for the purposes of determining whether the Warrant Agent will be
               protected in acting or relying on any such vote, consent,
               requisition or other instrument or action, only the Warrants
               which have been certified by WorldHeart in a certificate of
               WorldHeart to the Warrant Agent as so owned will be so
               disregarded; and

          (ii) Warrants so owned which have been pledged in good faith, other
               than to WorldHeart or an affiliate thereof, will not be so
               disregarded if the pledgee establishes to the satisfaction of the
               Warrant Agent the pledgee's right to vote such Warrants in its
               discretion free from the control of WorldHeart or an affiliate
               thereof.

1.3  Words Importing the Singular and Gender

     Words importing the singular include the plural and vice versa and words
importing a particular gender include all genders.

1.4  Interpretation Not Affected by Headings, Etc.

     The division of this Indenture into Articles, Sections, Subsections,
paragraphs, subparagraphs, clauses and subclauses and the insertion of headings
are for convenience of reference only and will not affect the construction or
interpretation of this Indenture.
<PAGE>
                                      -6-

1.5  Day Not a Business Day

     If the day on or before which any action that would otherwise be required
to be taken hereunder is not a business day in the place where the action is
required to be taken, that action will be required to be taken on or before the
requisite time on the next succeeding day that is a business day with the same
force and effect as if taken within the period for the taking of such action.

1.6  Time of the Essence

     Time will be of the essence in all respects in this Indenture and the
Warrant Certificates.

1.7  Currency

     Except as otherwise stated, all dollar amounts herein are expressed in
Canadian dollars.

1.8  Governing Law

     This Indenture and the Warrant Certificates issued pursuant hereto will be
construed and enforced in accordance with the laws in the Province of Ontario
and with the federal laws of Canada applicable therein and will be treated in
all respects as Ontario contracts. The parties irrevocably attorn and submit to
the non-exclusive jurisdiction of the courts of the Province of Ontario with
respect to any matter arising under or related to this Indenture.

1.9  Beneficiaries

     This Indenture is entered into by the Warrant Agent for the benefit of all
such persons who are issued Warrants in accordance with the terms of this
Indenture and each of them shall, upon such issuance, be entered in the register
as Warrantholders. The Warrant Agent hereby declares that it holds all rights,
interest and benefits to be derived therefrom for and on behalf of all such
persons in accordance with the terms and restrictions contained herein.

                                   ARTICLE 2

                                  THE WARRANTS

2.1  Creation and Authorization of Warrants

(1) Up to 10,655,000 Warrants, each Warrant entitling the holder thereof to be
issued one Common Share (subject to adjustment as provided herein) on the terms
and subject to the conditions herein provided, are hereby created and authorized
for issuance by the Warrant Agent on behalf of WorldHeart on the Effective Date
and thereafter.

(2) Warrant Certificates shall be executed by WorldHeart and delivered to the
Warrant Agent, certified by or on behalf of the Warrant Agent upon the written
order of WorldHeart and delivered by the Warrant Agent to WorldHeart or to the
order of WorldHeart pursuant to a
<PAGE>
                                      -7-

written direction of WorldHeart, without any further act of or formality on the
part of WorldHeart and without the Warrant Agent receiving any consideration
therefor.

2.2  Terms of Warrants

(1) Subject to Subsection 2.2(2) hereof, each Warrant issued hereunder will
entitle the holder thereof, upon the exercise thereof and payment of the
Exercise Price in accordance with the provisions of Article 4 hereof, to be
issued one Common Share.

(2) The Exercise Price and the number of Common Shares issuable on exercise of a
Warrant pursuant to Subsection 2.2(1) hereof, will be adjusted upon the
occurrence of the events and in the manner specified in Article 5.

2.3  Form of Warrant Certificates

(1) The Warrant Certificates (including the signature of the Warrant Agent
endorsed thereon) will be substantially in the form set out in Schedule A
hereto, will be dated as of the date hereof (regardless of the actual dates of
their issue), will bear such legends (including the legends described in
Sections 2.7 or 2.8 below, as applicable) and distinguishing letters and numbers
as WorldHeart, with the approval of the Warrant Agent, may prescribe and will be
issuable in any whole number denomination. No fractional Warrants will be issued
or otherwise provided for hereunder.

Regardless of any adjustments pursuant to Article 5 of this Indenture, Warrant
Certificates representing Warrants shall continue to be in the form set forth in
Schedule A to this Indenture and shall continue to express the number of Common
Shares which may be acquired upon the exercise of the Warrants evidenced thereby
prior to any such adjustments.

(2) The Warrant Certificates may be engraved, lithographed or printed (the
expression "printed" including for purposes hereof both original typewritten
material as well as mimeographed, mechanically, photographically,
photostatically or electronically reproduced, typewritten or other written
material), or partly in one form and partly in another, as WorldHeart may with
the approval of the Warrant Agent determine.

2.4  Signing of Warrant Certificates

(1) The Warrant Certificates will be signed by any director or officer of
WorldHeart or by any other individual to whom such signing authority is
delegated by the directors from time to time.

(2) The signatures of any of the officers or individuals referred to in
Subsection 2.4(1) may be manual signatures, engraved, lithographed or printed in
facsimile and Warrant Certificates bearing such facsimile signatures will be
binding on WorldHeart as if they had been manually signed by such officers or
individuals.

(3) Notwithstanding that any person whose manual or facsimile signature appears
on a Warrant Certificate as one of the officers or individuals referred to in
Subsection 2.4(1) no longer holds the same or any other office with WorldHeart
at the date of issuance of any Warrant Certificate
<PAGE>
                                      -8-

or at the date of certification or delivery thereof, such Warrant Certificate
will, subject to Section 2.5, be valid and binding on WorldHeart and such fact
shall not affect in any way the entitlement of the holder thereof to the
benefits of this Indenture or the Warrant Certificate(s) in question.

2.5  Certification by Warrant Agent

(1) No Warrant Certificate signed in accordance with Section 2.4 will be issued
or, if issued, will be valid or entitle the holder to the benefits hereof until
it has been certified by manual signature by or on behalf of the Warrant Agent
substantially in the form of the certificate set out in Schedule A or in such
other form approved by the Warrant Agent. The certification by the Warrant Agent
on a Warrant Certificate will be conclusive evidence as against WorldHeart that
such Warrant Certificate has been duly issued hereunder and that the holder
thereof is entitled to the benefits hereof.

(2) The certification by the Warrant Agent on any Warrant Certificate issued
hereunder will not be construed as a representation or warranty by the Warrant
Agent as to the validity of this Indenture (except in respect of its due
authorization, execution and delivery by, and enforceability against, the
Warrant Agent) or such Warrant Certificate (except the due certification
thereof) or as to performance by WorldHeart of its obligations hereunder, and
the Warrant Agent will in no respect be liable or answerable for the use made of
any Warrant Certificate or of the consideration therefor, except as otherwise
specified herein.

2.6  Warrants to Rank Pari Passu

     All Warrants will rank pari passu, whatever may be the actual dates of
issue of the Warrant Certificates by which they are evidenced.

2.7  Canadian Transfer Restrictions

     (1) In order to ensure compliance with Applicable Legislation, no direct or
indirect sale or transfer of Warrants or the underlying Common Shares shall be
permitted from or by a registered Holder whose address is in Canada to a
purchaser or transferee whose address is in Canada (or who is a resident of
Canada) or to a purchaser or transferee whose address is in the United States
(or who is a resident of the United States) unless it is made in compliance with
Applicable Legislation. Each Warrantholder in Canada, by its acceptance of the
Warrant, shall be deemed to have acknowledged and agreed that if the
Warrantholder is a resident of Canada it shall not transfer Warrants or
underlying Common Shares except as provided in the immediately preceding
sentence. Each Warrant originally issued to a person within Canada and all
Warrants issued in exchange therefor or in substitution thereof or upon transfer
thereof, shall bear the legends or similar legends to those set forth below (the
"Canadian Legend"):

(a) "UNLESS PERMITTED UNDER CANADIAN SECURITIES LEGISLATION, THE HOLDER OF THE
SECURITIES SHALL NOT TRADE THE SECURITIES BEFORE JANUARY 17, 2005."

(b) "THE SECURITIES REPRESENTED HEREBY (AND THE SECURITIES ISSUED UPON EXERCISE
HEREOF) HAVE NOT BEEN REGISTERED UNDER THE UNITED STATES SECURITIES ACT OF 1933,
AS AMENDED (THE "U.S. SECURITIES ACT") OR THE SECURITIES LAWS OF ANY STATE OF
THE UNITED STATES. THE HOLDER HEREOF, BY PURCHASING SUCH SECURITIES, AGREES
<PAGE>
                                      -9-

FOR THE BENEFIT OF THE CORPORATION THAT SUCH SECURITIES MAY BE OFFERED, SOLD,
PLEDGED OR OTHERWISE TRANSFERRED ONLY (A) TO THE CORPORATION, OR (B) OUTSIDE THE
UNITED STATES IN ACCORDANCE WITH RULE 903 OR 904 OF REGULATION S UNDER THE U.S.
SECURITIES ACT, IF APPLICABLE, OR (C) INSIDE THE UNITED STATES (1) PURSUANT TO
THE EXEMPTION FROM THE REGISTRATION REQUIREMENTS UNDER THE U.S. SECURITIES ACT
PROVIDED BY RULE 144 THEREUNDER, IF AVAILABLE, AND IN ACCORDANCE WITH APPLICABLE
STATE SECURITIES LAW OR (2) IN A TRANSACTION THAT DOES NOT OTHERWISE REQUIRE
REGISTRATION UNDER THE U.S. SECURITIES ACT OR ANY APPLICABLE STATE SECURITIES
LAW, PROVIDED THE HOLDER HAS FURNISHED TO THE CORPORATION AN OPINION OF COUNSEL
OF RECOGNIZED STANDING TO THAT EFFECT IN FORM AND SUBSTANCE REASONABLY
SATISFACTORY TO THE CORPORATION OR (3) PURSUANT TO A REGISTRATION STATEMENT
PURSUANT TO THE U.S. SECURITIES ACT."

     (2) In the event that the Common Shares issuable upon the exercise of
Warrants are issued prior to the date which is four months and one day after the
date issue the Common Shares shall in addition to the legends in Section
2.7(1)(a) and (b), bear the following legend:

     "THE SECURITIES REPRESENTED BY THIS CERTIFICATE ARE LISTED ON THE TORONTO
STOCK EXCHANGE; HOWEVER, THE SAID SECURITIES CANNOT BE TRADED THROUGH THE
FACILITIES OF SUCH EXCHANGE SINCE THEY ARE NOT FREELY TRANSFERABLE, AND
CONSEQUENTLY ANY CERTIFICATE REPRESENTING SUCH SECURITIES IS NOT "GOOD DELIVERY"
IN SETTLEMENT OF TRANSACTIONS ON THE TORONTO STOCK EXCHANGE."

     (3) In the event that the Common Shares issuable upon the exercise of
Warrants are issued after the date which is four months and one day after the
date of issue, the Common Shares shall bear the legends set forth below (the
"Modified Canadian Legend"):

(a) "THE SECURITIES REPRESENTED BY THIS CERTIFICATE ARE LISTED ON THE TORONTO
STOCK EXCHANGE; HOWEVER, THE SAID SECURITIES CANNOT BE TRADED THROUGH THE
FACILITIES OF SUCH EXCHANGE SINCE THEY ARE NOT FREELY TRANSFERABLE, AND
CONSEQUENTLY ANY CERTIFICATE REPRESENTING SUCH SECURITIES IS NOT "GOOD DELIVERY"
IN SETTLEMENT OF TRANSACTIONS ON THE TORONTO STOCK EXCHANGE."

(b) "THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE UNITED
STATES SECURITIES ACT OF 1933, AS AMENDED (THE "U.S. SECURITIES ACT") OR THE
SECURITIES LAWS OF ANY STATE OF THE UNITED STATES. THE HOLDER HEREOF, BY
PURCHASING SUCH SECURITIES, AGREES FOR THE BENEFIT OF THE CORPORATION THAT SUCH
SECURITIES MAY BE OFFERED, SOLD, PLEDGED OR OTHERWISE TRANSFERRED ONLY (A) TO
THE CORPORATION, OR (B) OUTSIDE THE UNITED STATES IN ACCORDANCE WITH RULE 903 OR
904 OF REGULATION S UNDER THE U.S. SECURITIES ACT, IF APPLICABLE, OR (C) INSIDE
THE UNITED STATES (1) PURSUANT TO THE EXEMPTION FROM THE REGISTRATION
REQUIREMENTS UNDER THE U.S. SECURITIES ACT PROVIDED BY RULE 144 THEREUNDER, IF
AVAILABLE, AND IN ACCORDANCE WITH APPLICABLE STATE SECURITIES LAW OR (2) IN A
TRANSACTION THAT DOES NOT OTHERWISE REQUIRE REGISTRATION UNDER THE U.S.
SECURITIES ACT OR ANY APPLICABLE STATE SECURITIES LAW, PROVIDED THE HOLDER HAS
FURNISHED TO THE CORPORATION AN OPINION OF COUNSEL OF RECOGNIZED STANDING TO
THAT EFFECT IN FORM AND SUBSTANCE REASONABLY SATISFACTORY TO THE CORPORATION OR
(3) PURSUANT TO A REGISTRATION STATEMENT PURSUANT TO THE U.S. SECURITIES ACT."

     (4) With respect to the Canadian Legend and the Modified Canadian Legend,
provided that either (i) a registration statement is declared effective by the
United States
<PAGE>
                                      -10-

Securities and Exchange Commission with respect to the Common Shares issuable
upon the exercise of Warrants, and receipt by the Corporation of the Holder's
written confirmation that such Common Shares will not be disposed of except in
compliance with the prospectus delivery requirements of the U.S. Securities Act
or (ii) Rule 144(k) becoming available, then the legend in Section 2.7(1)(b) or
Section 2.7(2)(b) above may be removed.

     (5) If the Common Shares issuable upon the exercise of the Warrant are
being sold outside the United States in accordance with Rule 903 or 904 of
Regulation S, the legends in Section 2.7(1)(b) or Section 2.7(2)(b) above may be
removed by providing a declaration to the Corporation's registrar and transfer
agent in the form attached as Exhibit 1 to the Warrant Certificate.

2.8  United States and European Transfer Restrictions

     (1) In order to ensure compliance with Applicable Legislation and
applicable United States securities laws, no direct or indirect sale, transfer
or repurchase of Warrants or the underlying Common Shares shall be permitted
from or by a registered holder whose address is in the United States to a
purchaser or transferee whose address is in the United States (or who is a
resident of the United States) or to a purchaser or transferee whose address is
in Canada (or who is a resident of Canada)or to a purchaser or transferee who
address is in Europe unless it is made in compliance with Applicable
Legislation, applicable United States securities laws or other applicable
securities laws. Each Warrantholder in the United States and Europe, by its
acceptance of Warrants, shall be deemed to have acknowledged and agreed that if
the Warrantholder is a resident of United States or Europe it shall not transfer
the Warrant or underlying Common Shares except as provided in the immediately
preceding sentence. Each Warrant originally issued to a person within the United
States or Europe and all Warrants issued in exchange therefor or in substitution
thereof or upon transfer thereof shall bear the following or similar legends set
forth below (the "U.S. Legend"):

(a) "THE HOLDER, BY ITS ACCEPTANCE OF THIS SECURITY, REPRESENTS, ACKNOWLEDGES,
AND AGREES THAT IT WILL NOT AND WILL NOT BE ENTITLED TO, DIRECTLY OR INDIRECTLY,
SELL OR TRANSFER THE SECURITIES INTO CANADA OR TO RESIDENTS OF CANADA, EXCEPT IN
COMPLIANCE WITH APPLICABLE CANADIAN SECURITIES LAWS. NO SALE OR TRANSFER INTO
CANADA OR TO A CANADIAN RESIDENT WILL BE REGISTERED BY WORLD HEART CORPORATION'S
TRANSFER AGENT AND ANY ATTEMPT TO EFFECT SUCH A TRANSFER IS INVALID UNLESS MADE
IN COMPLIANCE WITH THE ABOVE-NOTED RESTRICTIONS. "

(b) "UNLESS PERMITTED UNDER CANADIAN SECURITIES LEGISLATION, THE HOLDER OF THE
SECURITIES SHALL NOT TRADE THE SECURITIES BEFORE JANUARY 17, 2005."

(c) "THE SECURITIES REPRESENTED HEREBY (AND THE SECURITIES ISSUED UPON EXERCISE
HEREOF) HAVE NOT BEEN REGISTERED UNDER THE UNITED STATES SECURITIES ACT OF 1933,
AS AMENDED (THE "U.S. SECURITIES ACT") OR THE SECURITIES LAWS OF ANY STATE OF
THE UNITED STATES. THE HOLDER HEREOF, BY PURCHASING SUCH SECURITIES, AGREES FOR
THE BENEFIT OF THE CORPORATION THAT SUCH SECURITIES MAY BE OFFERED, SOLD,
PLEDGED OR OTHERWISE TRANSFERRED ONLY (A) TO THE CORPORATION, OR (B) OUTSIDE THE
UNITED STATES IN ACCORDANCE WITH RULE 903 OR 904 OF REGULATION S UNDER THE U.S.
SECURITIES ACT, IF APPLICABLE, OR (C) INSIDE THE UNITED STATES (1) PURSUANT TO
THE EXEMPTION FROM THE REGISTRATION REQUIREMENTS UNDER THE U.S. SECURITIES
<PAGE>
                                      -11-

ACT PROVIDED BY RULE 144 THEREUNDER, IF AVAILABLE, AND IN ACCORDANCE WITH
APPLICABLE STATE SECURITIES LAW OR (2) IN A TRANSACTION THAT DOES NOT OTHERWISE
REQUIRE REGISTRATION UNDER THE U.S. SECURITIES ACT OR ANY APPLICABLE STATE
SECURITIES LAW, PROVIDED THE HOLDER HAS FURNISHED TO THE CORPORATION AN OPINION
OF COUNSEL OF RECOGNIZED STANDING TO THAT EFFECT IN FORM AND SUBSTANCE
REASONABLY SATISFACTORY TO THE CORPORATION OR (3) PURSUANT TO A REGISTRATION
STATEMENT PURSUANT TO THE U.S. SECURITIES ACT."

     (2) In the event that the Common Shares issuable upon the exercise of
Warrants are issued prior to the date which is four months and one day after the
date issue the Common Shares shall in addition to the legends in Section
2.8(1)(a), (b) and (c), bear the following legend:

     "THE SECURITIES REPRESENTED BY THIS CERTIFICATE ARE LISTED ON THE TORONTO
STOCK EXCHANGE; HOWEVER, THE SAID SECURITIES CANNOT BE TRADED THROUGH THE
FACILITIES OF SUCH EXCHANGE SINCE THEY ARE NOT FREELY TRANSFERABLE, AND
CONSEQUENTLY ANY CERTIFICATE REPRESENTING SUCH SECURITIES IS NOT "GOOD DELIVERY"
IN SETTLEMENT OF TRANSACTIONS ON THE TORONTO STOCK EXCHANGE."

     (3) In the event that the Common Shares issuable upon the exercise of any
Warrant are issued after the date which is four months and one day after the
date of issue the Common Shares shall bear the legends set forth below (the
"Modified U.S. Legend"):

(a) "THE SECURITIES REPRESENTED BY THIS CERTIFICATE ARE LISTED ON THE TORONTO
STOCK EXCHANGE; HOWEVER, THE SAID SECURITIES CANNOT BE TRADED THROUGH THE
FACILITIES OF SUCH EXCHANGE SINCE THEY ARE NOT FREELY TRANSFERABLE, AND
CONSEQUENTLY ANY CERTIFICATE REPRESENTING SUCH SECURITIES IS NOT "GOOD DELIVERY"
IN SETTLEMENT OF TRANSACTIONS ON THE TORONTO STOCK EXCHANGE."

(b) "THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE UNITED
STATES SECURITIES ACT OF 1933, AS AMENDED (THE "U.S. SECURITIES ACT") OR THE
SECURITIES LAWS OF ANY STATE OF THE UNITED STATES. THE HOLDER HEREOF, BY
PURCHASING SUCH SECURITIES, AGREES FOR THE BENEFIT OF THE CORPORATION THAT SUCH
SECURITIES MAY BE OFFERED, SOLD, PLEDGED OR OTHERWISE TRANSFERRED ONLY (A) TO
THE CORPORATION, OR (B) OUTSIDE THE UNITED STATES IN ACCORDANCE WITH RULE 903 OR
904 OF REGULATION S UNDER THE U.S. SECURITIES ACT, IF APPLICABLE, OR (C) INSIDE
THE UNITED STATES (1) PURSUANT TO THE EXEMPTION FROM THE REGISTRATION
REQUIREMENTS UNDER THE U.S. SECURITIES ACT PROVIDED BY RULE 144 THEREUNDER, IF
AVAILABLE, AND IN ACCORDANCE WITH APPLICABLE STATE SECURITIES LAW OR (2) IN A
TRANSACTION THAT DOES NOT OTHERWISE REQUIRE REGISTRATION UNDER THE U.S.
SECURITIES ACT OR ANY APPLICABLE STATE SECURITIES LAW, PROVIDED THE HOLDER HAS
FURNISHED TO THE CORPORATION AN OPINION OF COUNSEL OF RECOGNIZED STANDING TO
THAT EFFECT IN FORM AND SUBSTANCE REASONABLY SATISFACTORY TO THE CORPORATION OR
(3) PURSUANT TO A REGISTRATION STATEMENT PURSUANT TO THE U.S. SECURITIES ACT."

(4) With respect to the U.S. Legend and the Modified U.S. Legend, provided that
either (i) a registration statement is declared effective by the United States
Securities and Exchange Commission with respect to the Common Shares issuable
upon the exercise of Warrants, and receipt by the Corporation of the Holder's
written confirmation that such Common Shares will not be disposed of except in
compliance with the prospectus delivery requirements of the U.S.
<PAGE>
                                      -12-

Securities Act or (ii) Rule 144(k) becoming available, then the legend in
Section 2.8(1)(c) and Section 2.8(3)(b) above may be removed.

(5) At any time a legend can be removed from the Common Share certificates,
WorldHeart shall provide notice and an appropriate direction to the Warrant
Agent and the transfer agent for WorldHeart's Common Shares with respect to the
removal of such legends.

2.9  Reliance by Warrant Agent

     The Warrant Agent shall have no obligation to ensure or verify compliance
with any applicable laws or regulatory requirements on the issue, exercise or
transfer of any Warrants or any Common Shares. The Warrant Agent shall be
entitled to process all proffered transfers and exercises of Warrants upon the
presumption that such transfers or exercises are permissible pursuant to all
applicable laws and regulatory requirements and the terms of this Indenture and
the related Warrant Certificates, provided that such transfers and exercises of
Warrants may only be processed by the Warrant Agent upon written instruction of
WorldHeart to the Warrant Agent, which instruction may be based, in WorldHeart's
reasonable discretion, upon certificates, opinions and other documentation of
the holders of such Warrants that such transfer or exercise is in accordance
with Applicable Legislation. The Warrant Agent may assume for the purposes of
this Indenture that the address on the register of Warrantholders of any
Warrantholder is the Warrantholder's actual address and is also determinative of
the Warrantholder's residency and that the address of any transferee to whom any
Warrants or Common Shares are to be registered, as shown on the transfer
document, is the transferee's actual address and is also determinative of the
transferee's residency.

2.10 Issue in Substitution for Lost Certificates, Etc.

(1) If any Warrant Certificate becomes mutilated or is lost, destroyed or
stolen, WorldHeart, subject to applicable law and to Subsection 2.11(2), shall
issue, and thereupon the Warrant Agent will certify and deliver, a new Warrant
Certificate of like tenor and for the purchase of a like number of Common Shares
as the one mutilated, lost, destroyed or stolen in exchange for and in place of
and on surrender and cancellation of such mutilated Warrant Certificate or in
lieu of and in substitution for such lost, destroyed or stolen Warrant
Certificate and the substituted Warrant Certificate shall be in a form approved
by the Warrant Agent and the Warrant evidenced thereby shall entitle the holder
to the benefits hereof and rank pari passu in accordance with its terms and with
all other Warrants issued hereunder.

(2) The applicant for the issue of a new Warrant Certificate pursuant to this
Section 2.11 will bear the reasonable cost of the issue thereof and in case of
loss, destruction or theft shall, as a condition precedent to the issue thereof:

     (a)  furnish to WorldHeart and to the Warrant Agent such evidence of
          ownership and of the loss, destruction or theft of the Warrant
          Certificate to be replaced as is satisfactory to WorldHeart and to the
          Warrant Agent each in their discretion, acting reasonably;
<PAGE>
                                      -13-

     (b)  if so required by WorldHeart or the Warrant Agent, furnish an
          indemnity or bond in amount and form satisfactory to WorldHeart and to
          the Warrant Agent each in their discretion, acting reasonably; and

     (c)  pay the reasonable charges of the Warrant Agent in connection
          therewith.

2.11 Cancellation of Surrendered Warrants

     All Warrant Certificates surrendered to the Warrant Agent pursuant to
Sections 2.11, 3.1, 3.2, 4.1 or 4.6 will be cancelled by the Warrant Agent and,
if requested by WorldHeart in writing, the Warrant Agent will furnish to
WorldHeart a cancellation certificate identifying each Warrant Certificate so
cancelled and the number of Warrants evidenced thereby.

2.12 Warrantholder not a Shareholder

     Nothing in this Indenture or in the holding of a Warrant evidenced by a
Warrant Certificate, or otherwise, is intended or will confer or be construed as
conferring on any Warrantholder any right or interest whatsoever as a
shareholder of WorldHeart, including but not limited to any right to vote at, to
receive notice of, or to attend any meeting of shareholders or any other
proceeding of WorldHeart or any right to receive any dividend or other
distribution to which the shareholders of WorldHeart may be entitled.

2.13 Expiration of Warrants

     At the Expiry Time all rights under the Warrants that for any reason has
not been exercised will wholly cease and terminate and the Warrant Certificates
therefor will be void and of no effect or value.

                                   ARTICLE 3

                      REGISTRATION, TRANSFER, EXCHANGE AND
                              OWNERSHIP OF WARRANTS

3.1  Registration and Transfer of Warrants

(1) WorldHeart hereby appoints the Warrant Agent as registrar and transfer agent
of the Warrants.

(2) The Warrant Agent will cause to be kept, by and at the principal offices in
Toronto, Ontario:

     (a)  a register (or registers) of holders in which shall be entered in
          alphabetical order the names and addresses of the holders of Warrants
          and particulars of the Warrants held by them; and

     (b)  a register of transfers in which all transfers of Warrants and the
          date and other particulars of each transfer shall be entered.
<PAGE>
                                      -14-

(3) No transfer of any Warrant will be valid unless duly entered on the
appropriate register of transfers referred to in Subsection 3.1(2), or on any
branch registers maintained pursuant to Subsection 3.1(8), upon surrender to the
Warrant Agent of the Warrant Certificate evidencing such Warrant, duly endorsed
by, or accompanied by a written instrument of transfer substantially in the form
of Appendix 2 to the Warrant Certificate or otherwise in form satisfactory to
the Warrant Agent executed by the registered holder or his executors,
administrators or other legal representatives or his or their attorney duly
appointed by an instrument in writing in form and execution satisfactory to the
Warrant Agent, and, subject to compliance with Sections 2.7, 2.8 and
4.6(a)(vii), and such requirements and such other reasonable requirements as the
Warrant Agent may prescribe, such transfer will be duly noted on one of such
registers of transfers by the Warrant Agent within two business days of the
satisfaction of all such requirements.

(4) The transferee of any Warrant will, after surrender to the Warrant Agent of
the Warrant Certificate evidencing such Warrant as required by Subsection 3.1(3)
and upon compliance with all other conditions in respect thereof required by
this Indenture or by law, be entitled to be entered on the register of holders
referred to in Subsection 3.1(2), or on any branch registers of holders
maintained pursuant to subsection 3.1(8), as the owner of such Warrant free from
all equities or rights of set-off or counterclaim between WorldHeart and the
transferor or any previous holder of such Warrant, except in respect of equities
of which WorldHeart is required to take notice by statute or by order of a court
of competent jurisdiction.

(5) WorldHeart will be entitled, and may direct the Warrant Agent in writing, to
refuse to recognize any transfer, or enter the name of any transferee, of any
Warrant on the registers referred to in Subsection 3.1(2), or on any branch
registers maintained pursuant to Subsection 3.1(8), if such transfer would
require WorldHeart to qualify the Common Shares issuable on exercise of the
Warrants for distribution in any jurisdiction other than the Qualifying
Jurisdictions.

(6) Neither WorldHeart nor the Warrant Agent will be bound to take notice of or
see to the execution of any trust, whether express, implied or constructive, in
respect of any Warrant, and may transfer any Warrant on the written direction of
the person registered as the holder thereof and delivered in accordance with
Subsection 3.1(3), whether named as trustee or otherwise, as though that person
were the beneficial owner thereof.

(7) The registers referred to in Subsection 3.1(2), and any branch registers
maintained pursuant to Subsection 3.1(8), will at all reasonable times be open
for inspection during normal business hours by WorldHeart and any Warrantholder.
The Warrant Agent will from time to time when requested to do so in writing by
WorldHeart or any Warrantholder (upon payment of the Warrant Agent's reasonable
charges), furnish WorldHeart or such Warrantholder with a list of the names and
addresses of holders of Warrants entered on such registers and showing the
number of Warrants held by each such holder.

(8) The Warrant Agent with the approval of WorldHeart, may at any time and from
time to time change the place at which the registers referred to in Subsection
3.1(2) are kept, cause branch registers of holders or transfers to be kept at
other places and close such branch registers or
<PAGE>
                                      -15-

change the place at which such branch registers are kept. Notice of any such
change or closure shall be given by the Warrant Agent to WorldHeart and the
holders of Warrants.

(9) The Warrant Agent shall retain until the sixth anniversary of the Expiry
Time all instruments of transfer of Warrants which are tendered for registration
including the details shown thereon of the persons by or through whom they were
lodged, all cancelled Warrants and other related documents.

3.2  Exchange of Warrant Certificates

(1) One or more Warrant Certificates may, on compliance by the holder with the
reasonable requirements of the Warrant Agent, be exchanged for one or more
Warrant Certificates of different denomination evidencing in the aggregate the
same number of Warrants as the Warrant Certificate or Warrant Certificates being
exchanged, and such holder shall pay the reasonable cost thereof.

(2) Warrant Certificates may be exchanged only at the principal office in
Toronto, Ontario of the Warrant Agent or at any other place designated by
WorldHeart with the approval of the Warrant Agent.

(3) Any Warrant Certificate tendered for exchange shall be surrendered to the
Warrant Agent or its agent and cancelled.

(4) WorldHeart will sign all Warrant Certificates necessary to carry out
exchanges pursuant to this Section 3.2 and the Warrant Agent shall certify such
Warrant Certificates.

3.3  Reasonable Charges for Transfer

     A presenter of a Warrant Certificate pursuant to this Indenture may be
charged the reasonable costs of the Warrant Agent for the transfer of any
Warrant or exchange of any Warrant Certificate.

3.4  Ownership of Warrants

(1) WorldHeart and the Warrant Agent may deem and treat the person in whose name
any Warrant is registered as the absolute owner of such Warrant for all
purposes, and such person will for all purposes of this Indenture be and be
deemed to be the absolute owner thereof, and WorldHeart and the Warrant Agent
will not be affected by any notice or knowledge to the contrary except as
required by statute or by order of a court of competent jurisdiction.

(2) The registered holder of any Warrant will be entitled to the rights
evidenced thereby free from all equities and rights of set-off or counterclaim
between WorldHeart and the original or any intermediate holder thereof and all
persons may act accordingly, and the delivery to any such registered holder of
the Common Shares issued on exercise of such Warrant will be a good discharge to
WorldHeart and the Warrant Agent therefor and, unless WorldHeart or the Warrant
Agent are required by statute or by an order of a court of competent
jurisdiction, neither
<PAGE>
                                      -16-

WorldHeart nor the Warrant Agent will be bound to inquire into the title of any
such registered holder.

3.5  Assumption by Transferee

     Upon becoming a Warrantholder in accordance with the provisions of this
Indenture, the transferee thereof shall be deemed to have acknowledged and
agreed to be bound by this Indenture. Upon the registration by the Warrant Agent
of such transferee as the holder of a Warrant, the transferor thereof shall
cease to have any further rights under this Indenture with respect to such
Warrant or any Common Shares to be issued on exercise.

                                   ARTICLE 4

                              EXERCISE OF WARRANTS

4.1  Exercise

(1) Subject to the limitation set forth in Subsection 4.1(2) and Section 4.5,
holders of Warrants may at any time prior to the Expiry Time exercise the right
thereby conferred, in whole or in part, to be issued Common Shares by
surrendering to the Warrant Agent at its principal offices in Toronto, Ontario
or to any other person or at any other place designated by WorldHeart with the
approval of the Warrant Agent, during normal business hours on a business day at
such place, the Warrant Certificate evidencing such Warrants and by payment by
certified cheque or bank draft to WorldHeart in the amount of the Exercise Price
in respect of each Common Share to be issued and by delivering a duly completed
and executed notice of exercise substantially in the form set out in Appendix 1
to such Warrant Certificate, provided such notice is also given to WorldHeart by
either the Warrantholder or the Warrant Agent by delivering to WorldHeart a copy
of such documents.

(2) Any certified cheque, bank draft, Warrant Certificate or notice of exercise
referred to in Subsection 4.1(1) will be deemed to have been surrendered or
delivered only on personal delivery thereof to, or, if sent by mail or other
means of transmission, on actual receipt thereof by, the Warrant Agent or one of
the other persons at the office or one of the other places specified in
Subsection 4.1(1).

(3) Any notice of exercise referred to in Subsection 4.1(1) must be signed by
the Warrantholder, or such Warrantholder's officers, employees, members,
partners, managers, executors, administrators or other legal representatives or
his or their attorney duly appointed by an instrument in writing in form and
execution satisfactory to the Warrant Agent, acting reasonably, and, if any
Common Shares thereby issuable are to be issued to a person or persons other
than the Warrantholder such issuance must be in accordance with applicable laws
(as determined by WorldHeart) and must specify the name or names and the address
or addresses of each such person or persons and the number of Common Shares to
be issued to each such person if more than one is so specified.

(4) The holder of any Warrant Certificate who wishes to exercise the Warrants
evidenced by such Warrant Certificate may exercise less than all of such
Warrants and in the case of any such
<PAGE>
                                      -17-

partial exercise shall be entitled to receive, without charge therefor, a
Warrant Certificate, in form, signed and certified in accordance with the
provisions of Article 2, evidencing the number of Warrants held by the
Warrantholder which remain unexercised. Such Warrant Certificate will be
delivered by the Warrant Agent to the holder concurrently with the certificates
representing the Common Shares issued on partial exercise of such holder's
Warrants.

4.2  Effect of Exercise

(1) Upon the exercise of any Warrant in accordance with Section 4.1, the Common
Shares thereby issuable will be deemed to have been issued, and the person or
persons to whom such Common Shares are to be issued will be deemed to have
become the holder or holders of record thereof on the Exercise Date, unless the
transfer registers for the Common Shares are closed on that date, in which case
such Common Shares will be deemed to have been issued and such person or persons
will be deemed to have become the holder or holders of record thereof on the
date on which such transfer registers are reopened, but such Common Shares will
be issued on the basis of the number of Common Shares to which such person or
persons were entitled on the Exercise Date.

(2) As soon as practicable and in any event not later than the fifth business
day on which the transfer registers for the Common Shares have been open after
such exercise, WorldHeart will cause the Warrant Agent to deliver to the person
or persons in whose name or names the Common Shares thereby issued have been
issued, at his or their respective addresses, or, if so specified, cause to be
delivered to such person or persons at the place where the Warrant Certificate
evidencing such Warrant was surrendered, certificates representing the Common
Shares so issued.

(3) WorldHeart will pay any documentary stamp taxes attributable to the initial
issuance of the Common Shares pursuant to any Warrant. If any Common Shares
issuable pursuant to any Warrant are to be issued to a person or persons other
than the Warrantholder, the Warrantholder must pay to WorldHeart or to the
Warrant Agent on its behalf an amount equal to all exigible transfer taxes or
other government charges, and WorldHeart will not be required to issue or
deliver any certificates representing any such Common Shares unless or until
such amount has been so paid or the Warrantholder has established to the
satisfaction of WorldHeart that such taxes and charges have been paid or that no
such taxes or charges are owing.

4.3  No Fractional Common Shares

     WorldHeart shall not be required, notwithstanding the adjustment
provisions, to issue fractional Common Shares upon the exercise of Warrants. To
the extent that a holder of Warrants would otherwise have been entitled to
receive, on the exercise of Warrants, a fraction of a Common Share, such right
may only be exercised in respect of such fraction in connection with another
Warrant or Warrants which in the aggregate entitle the holder to receive a whole
number of Common Shares. If a Warrantholder is not able to combine Warrants so
as to be entitled to acquire a whole number of Common Shares, the number of
Common Shares which such Warrantholder is entitled to receive upon exercise of
Warrants shall be rounded down to the prior whole number.
<PAGE>
                                      -18-

4.4  Recording

     The Warrant Agent will record particulars of each Warrant exercised which
will include the name and address of each person to whom Common Shares are
thereby issued, the number of Common Shares so issued and the Exercise Date in
respect thereof. Within five business days after each Exercise Date the Warrant
Agent will provide such particulars in writing to WorldHeart.

4.5  Securities Restrictions

If the Exercise Date in respect of any Warrant occurs before the Legend Date,
certificates representing Common Shares thereby issued will bear such legends as
may, in the opinion of counsel to WorldHeart, be necessary or advisable in order
to avoid a violation of any applicable securities laws of any province or
territory of Canada, of the United States of America or any jurisdiction or to
comply with the requirements of any stock exchange on which the Common Shares
are then listed, provided that if, at any time, in the opinion of counsel to
WorldHeart, such legends are no longer necessary or advisable in order to avoid
a violation of any such laws or requirements, or the holder of any such legended
certificate, at his expense, provides WorldHeart with evidence satisfactory in
form and substance to WorldHeart (which may include an opinion of counsel
satisfactory to WorldHeart) to the effect that such holder is entitled to sell
or otherwise transfer such Common Shares in a transaction in which such legends
are not required, such legended certificate may thereafter be surrendered to the
Warrant Agent in exchange for a certificate which does not bear such legends.

4.6  Call Provisions

     (a)  Notwithstanding any other provision contained in this Warrant
          Indenture or the Warrant Certificate to the contrary:

          (i)  subject to the provisions of clauses (ii) through (viii), in the
               event that the closing price of the Common Shares as traded on
               NASDAQ (or such other exchange or stock market on which the
               Common Shares may then be listed or quoted) equals or exceeds
               US$4.50 (appropriately adjusted for any stock split, reverse
               stock split, stock dividend or other reclassification or
               combination of the Common Shares occurring after the date hereof)
               for 20 consecutive Trading Days (the "Trading Condition"),
               WorldHeart, upon 30 days prior written notice (the "Notice
               Period") given to all Warrantholders immediately following such
               20 Trading Day period, may demand that the Warrantholders
               exercise a portion of their rights under the Warrants, as
               described below in paragraph (ii), and the Warrantholders must
               exercise their rights prior to the expiration of the Notice
               Period or if such exercise is not made or if only a partial
               exercise is made, any and all rights to further exercise rights
               with respect to that portion of their Warrants shall cease upon
               the expiration of the Notice Period (the "Warrant Reduction");
<PAGE>
                                      -19-

          (ii) in any three-month period no more than the lesser of (i) 20% of
               the aggregate amount of Warrants initially issued to a
               Warrantholder or (ii) the number of Warrants held by the
               Warrantholder, may be called by WorldHeart and WorldHeart may not
               call additional Warrants in any subsequent three-month period
               unless all the conditions specified in this Section 4.6 are again
               met (including without limitation, the Trading Condition) at the
               time that any subsequent call notice is given;

          (iii) it is a condition of WorldHeart exercising its rights under this
               Section 4.6 that (i) with respect to the holders of the Warrants
               that all of the Common Shares issuable under the Warrants issued
               to the holders of the Warrants either (A) are registered, or have
               been given the opportunity to register and have declined to
               register, pursuant to an effective registration statement which
               is available for sales of Common Shares during the Notice Period,
               or (B) are freely tradeable in the United States by the holder
               thereof;

          (iv) with respect to all Warrantholders WorldHeart must simultaneously
               call all Warrants on the same terms and for the purposes of
               paragraphs 4.6(a)(i), (ii), (iv) and (vii) such provisions shall
               be deemed to apply to the Agent's Warrants;

          (v)  in the event that a Warrantholder fails to exercise their rights
               with respect to the Warrants which have been called pursuant to
               clause (i) above, WorldHeart shall notify the Warrant Agent in
               writing that a Warrant Reduction has occurred, which notice shall
               specify those Warrantholders who are subject to the Warrant
               Reduction and the number of Warrants subject to the Warrant
               Reduction and Warrant Agent shall also send notice to the
               affected Warrantholders identifying the number of Warrants
               subject to the Warrant Reduction;

          (vi) the Warrant Agent shall maintain a register showing each
               Warrantholder and any Warrant Reduction amount with respect to
               that Warrantholder and in the event that the Warrantholder
               exercises part of or transfers the Warrants, the Warrant Agent
               shall issue a new Warrant Certificate evidencing that number of
               Warrants equal to the face amount thereof less any such Warrant
               Reduction amount(s);

          (vii) it shall be a condition to any transfer or exchange of Warrants
               that the transferring Warrantholder deliver to the Warrant Agent
               and WorldHeart an agreement executed by the transferring
               Warrantholder and the new Warrantholder pursuant to which they
               agree to allocate on a pro rata basis any call of Warrants by
               WorldHeart, such that WorldHeart shall have the right to call the
               same number of Warrants that it would have called as if the
               transfer or exchange has not occurred, occurring from and after
               the effective date of such transfer or exchange;
<PAGE>
                                      -20-

          (viii) where a notice pursuant to this Section 4.6 has been given, the
               Warrant Agent shall be entitled to act and rely on any direction
               of WorldHeart or WorldHeart's auditors and the Warrant Agent
               shall not at any time be under any duty or responsibility to any
               Warrantholder to determine whether any facts exist which may
               require any adjustment in the holdings of any Warrantholder
               pursuant to this Section 4.6.

                                   ARTICLE 5

                                   ADJUSTMENTS

5.1  Adjustments

     The rights of the holder of any Warrant, including the number of Common
Shares issuable upon the exercise of such Warrant and the Exercise Price payable
on exercise of such Warrant, shall be adjusted from time to time in the events
and in the manner provided in, and in accordance with, this Article 5.

     (a)  If WorldHeart shall, at any time or from time to time while any
          Warrant is outstanding, pay a dividend or make a distribution on its
          Common Shares, subdivide its outstanding Common Shares into a greater
          number of shares, or combine its outstanding Common Shares into a
          smaller number of shares or issue, by reclassification of its
          outstanding Common Shares, any shares of its capital stock (including
          any such reclassification in connection with a consolidation or merger
          in which WorldHeart is the continuing corporation), then the number of
          Common Shares issuable upon exercise of the Warrants and the Exercise
          Price in effect immediately prior to the date upon which such change
          shall become effective, shall be adjusted by WorldHeart so that the
          Warrantholder thereafter exercising the Warrant shall be entitled to
          receive the number of Common Shares or other capital stock which the
          Warrantholder would have received if the Warrant had been exercised
          immediately prior to such event upon payment of an Exercise Price that
          has been adjusted to reflect a fair allocation of the economics of
          such event to the Warrantholder as determined in good faith by the
          directors of WorldHeart. Such adjustments shall be made successively
          whenever any event listed above shall occur.

     (b)  If any capital reorganization, reclassification of the capital stock
          of WorldHeart, consolidation or merger of WorldHeart with another
          corporation in which WorldHeart is not the survivor, or amalgamation
          with, or sale, transfer or other disposition of all or substantially
          all of WorldHeart's assets to another corporation shall be effected,
          then, as a condition of such reorganization, reclassification,
          consolidation, merger, amalgamation, sale, transfer or other
          disposition, lawful and adequate provision shall be made whereby each
          Warrantholder shall thereafter have the right to purchase and receive
          upon the basis and upon the terms and conditions herein specified and
          in lieu of the Common Shares immediately theretofore issuable upon
          exercise of the Warrant, such shares of
<PAGE>
                                      -21-

          stock, securities or assets as would have been issuable or payable
          with respect to or in exchange for a number of Common Shares equal to
          the number of Common Shares immediately theretofore issuable upon
          exercise of the Warrant, had such reorganization, reclassification,
          consolidation, merger, amalgamation, sale, transfer or other
          disposition not taken place, and in any such case appropriate
          provision shall be made with respect to the rights and interests of
          each Warrantholder to the end that the provisions hereof (including,
          without limitation, provision for adjustment of the Exercise Price)
          shall thereafter be applicable, as nearly equivalent as may be
          practicable in relation to any shares of stock, securities or assets
          thereafter deliverable upon the exercise thereof. WorldHeart shall not
          effect any such consolidation, merger, amalgamation, sale, transfer or
          other disposition unless prior to or simultaneously with the
          consummation thereof the successor corporation (if other than
          WorldHeart) resulting from such consolidation, merger or amalgamation,
          or the corporation purchasing or otherwise acquiring such assets or
          other appropriate corporation or entity shall assume the obligation to
          deliver to the holder of the Warrant, at the last address of such
          holder appearing on the books of the Warrant Agent, such shares,
          securities or assets as, in accordance with the foregoing provisions,
          such holder may be entitled to purchase, and the other obligations
          under the Warrant. The provisions of this paragraph (b) shall
          similarly apply to successive reorganizations, reclassifications,
          consolidations, mergers, amalgamations, sales, transfers or other
          dispositions.

     (c)  In case WorldHeart shall fix a payment date for the making of a
          distribution to all holders of Common Shares (including any such
          distribution made in connection with a consolidation, merger or
          amalgamation in which WorldHeart is the continuing corporation) of
          evidences of indebtedness or assets (other than cash dividends or cash
          distributions payable out of consolidated earnings or earned surplus
          or dividends or distributions referred to in Section 5(a)), or
          subscription rights or warrants, the Exercise Price to be in effect
          after such payment date shall be determined by multiplying the
          Exercise Price in effect immediately prior to such payment date by a
          fraction, the numerator of which shall be the total number of Common
          Shares outstanding multiplied by the Current Market Price per Common
          Share immediately prior to such payment date, less the fair market
          value (as determined by the directors of WorldHeart in good faith) of
          said assets or evidences of indebtedness so distributed, or of such
          subscription rights or warrants, and the denominator of which shall be
          the total number of shares of Common Shares outstanding multiplied by
          such Current Market Price per share of Common Shares immediately prior
          to such payment date. Such adjustment shall be made successively
          whenever such a payment date is fixed.

     (d)  For the term of the Warrants, in addition to the provisions contained
          above, the Exercise Price shall be subject to adjustment as provided
          below. An adjustment to the Exercise Price shall become effective
          immediately after the payment date in the case of each dividend or
          distribution and immediately after the effective date of each other
          event which requires an adjustment.
<PAGE>
                                      -22-

     (e)  In the event that, as a result of an adjustment made pursuant to this
          Section 5, the holder of the Warrant shall become entitled to receive
          any shares of capital stock of WorldHeart other than Common Shares,
          the number of such other shares so receivable upon exercise of the
          Warrant shall be subject thereafter to adjustment from time to time in
          a manner and on terms as nearly equivalent as practicable to the
          provisions with respect to the Common Shares contained in the Warrant.

(2) At least ten days before the earlier of the effective date of or record date
for any event referred to in this Article 5 that requires or might require an
adjustment in any of the rights under the Warrants or such longer notice period
as may be applicable in respect of notices required to be delivered by
WorldHeart to holders of its Common Shares, WorldHeart will:

     (a)  file with the Warrant Agent a certificate of WorldHeart specifying the
          particulars of such event and, to the extent determinable, any
          adjustment required and the computation of such adjustment; and

     (b)  give notice to the Warrantholders of the particulars of such event
          and, to the extent determinable, any adjustment required and a
          description of how such adjustment will be calculated.

Such notice need only set forth such particulars as have been determined at the
date such notice is given. If any adjustment for which such notice is given is
not then determinable, promptly after such adjustment is determinable WorldHeart
will:

     (a)  file with the Warrant Agent a certificate of WorldHeart showing the
          computation of such adjustment; and

     (b)  give notice to the Warrantholders of such adjustment.

Where a notice pursuant to this Subsection 5.1(2) has been given, the Warrant
Agent shall be entitled to act and rely on any adjustment calculation of
WorldHeart or WorldHeart's auditors.

(3) The Warrant Agent shall not:

     (a)  at any time be under any duty or responsibility to any Warrantholder
          to determine whether any facts exist which may require any adjustment
          in the Exercise Price, or with respect to the nature or extent of any
          such adjustment when made, or with respect to the method employed in
          making same;

     (b)  be accountable with respect to the validity or value (or the kind or
          amount) of any Common Shares or of any shares or other securities or
          property which may at any time be issued or delivered upon the
          exercise or deemed exercise of any Warrant; or

     (c)  be responsible for any failure of WorldHeart to make any cash payment
          or to issue, transfer or deliver Common Shares or certificates
          representing Common
<PAGE>
                                      -23-

          Shares upon the surrender of any Warrant for the purpose of exercise,
          or to comply with any of the covenants contained in this Article
          5.

                                   ARTICLE 6

                          COVENANTS AND REPRESENTATIONS

6.1  General Covenants and Representations

     WorldHeart represents, warrants, covenants and agrees with the Warrant
Agent that so long as any Warrant remains outstanding and may be exercised:

     (a)  WorldHeart is duly authorized to create and issue the Warrants and
          that the Warrant Certificates, when issued and countersigned as herein
          provided, will be valid and enforceable against WorldHeart;

     (b)  WorldHeart will at all times maintain its corporate existence, carry
          on and conduct its business in a proper and business-like manner, keep
          or cause to be kept proper books of account in accordance with
          generally accepted accounting principles and WorldHeart will send to
          Warrantholders copies of all financial statements furnished to its
          shareholders during the term of this Indenture;

     (c)  WorldHeart will reserve for the purpose and keep available sufficient
          unissued Common Shares to enable it to satisfy its obligations to
          issue Common Shares on the exercise of the Warrants;

     (d)  until the Expiry Time of the Warrants, WorldHeart will not amend this
          Indenture without the approval of the holders of Warrants as set forth
          in Article 8 hereof, unless such amendment would otherwise be
          permitted under Article 9 hereof;

     (e)  WorldHeart will cause the Common Shares from time to time to be duly
          issued pursuant to the exercise of the Warrants, and the certificates
          representing such Common Shares, to be duly issued and delivered in
          accordance with the Warrants and the terms hereof;

     (f)  all Common Shares that are issued on due exercise of the Warrants
          shall be, at the time of delivery of the certificates therefore, duly
          authorized, and validly issued as fully paid and non-assessable;

     (g)  WorldHeart will cause the Warrant Agent to keep open on business days
          the registers of holders and registers of transfers referred to in
          Section 3.1 and will not take any action or omit to take any action
          which would have the effect of preventing the Warrantholders from
          exercising any of the Warrants or receiving any of the Common Shares
          upon such exercise;
<PAGE>
                                      -24-

     (h)  WorldHeart will make all requisite filings, including filings with
          appropriate Canadian securities regulatory authorities, in connection
          with the exercise of the Warrants and issue of the Common Shares;

     (i)  WorldHeart will use its best commercial efforts to ensure that all
          Common Shares outstanding or issuable from time to time including the
          Common Shares issuable upon exercise of the Warrants continue to be or
          are listed for trading on NASDAQ or a U.S. stock exchange; and

     (j)  generally, WorldHeart will well and truly perform and carry out all
          acts and things to be done by it as provided in this Indenture and
          will not take any action which might reasonably be expected to deprive
          the Warrantholders of their rights to acquire Common Shares upon the
          exercise of the Warrants.

6.2  Warrant Agent's Remuneration and Expenses

     WorldHeart will pay to the Warrant Agent from time to time reasonable
remuneration for its services hereunder and will, on the Warrant Agent's
request, pay to or reimburse the Warrant Agent for all reasonable documented
expenses, disbursements and advances made or incurred by the Warrant Agent in
the administration or execution of the trusts hereof (including reasonable
documented compensation and disbursements of its counsel and other advisers and
assistants not regularly in its employ), both before any default hereunder and
thereafter until all duties of the Warrant Agent hereunder have been finally and
fully performed, except any such expense, disbursement or advance that arises
out of or results from negligence, wilful misconduct or bad faith of the Warrant
Agent or of persons for whom the Warrant Agent is responsible. The
Warrantholders shall not be liable for any portion of such fees or expenses
except as otherwise specified herein.

6.3  Performance of Covenants by Warrant Agent

     If the Warrant Agent is made aware of the failure of WorldHeart to perform
any of its obligations under this Indenture, the Warrant Agent may notify the
Warrantholders of such failure or may itself perform any of such obligations
capable of being performed by it, but, subject to Section 10.3, will not be
bound to do so or to notify the Warrantholders that it is so doing. All sums
expended or advanced by the Warrant Agent in so doing will be repayable as
provided in Section 6.2. No such performance, expenditure or advance by the
Warrant Agent will relieve WorldHeart of any default or of its continuing
obligations hereunder.

                                   ARTICLE 7

                                   ENFORCEMENT

7.1  Legal Proceedings by Warrantholders

     All or any of the rights conferred upon a Warrantholder by the terms of the
Warrant Certificates evidencing the Warrants held by such Warrantholder or this
Indenture, or both, may
<PAGE>
                                      -25-

be enforced by the Warrantholder by appropriate legal proceedings, but without
prejudice to the right which is hereby conferred upon the Warrant Agent under
Section 7.2.

7.2  Warrant Agent May Institute All Proceedings

(1) The Warrant Agent shall also have the power at any time and from time to
time to institute and to maintain such suits and proceedings as it may be
advised shall be necessary or advisable to preserve and protect its interests
and the interests of the Warrantholders.

(2) Any such suit or proceeding instituted by the Warrant Agent may be brought
in the name of the Warrant Agent as trustee of an express trust, and any
recovery of judgment shall be for the rateable benefit of the holders of the
Warrants subject to the provisions of this Indenture. In any proceeding brought
by the Warrant Agent (and also any proceeding in which a declaratory judgment of
a court may be sought as to the interpretation or construction of any provision
of this Indenture, to which the Warrant Agent shall be a party) the Warrant
Agent shall be held to represent all the holders of the Warrants, and it shall
not be necessary to make any holders of the Warrants parties to any such
proceeding.

7.3  Limitation of Liability

     The obligations hereunder are not personally binding on, nor shall resort
hereunder be had to, the private property of, any past, present or future
director, shareholder, officer, employee or agent of WorldHeart but only the
property of WorldHeart shall be bound in respect hereof.

7.4  Immunity of Shareholders, etc.

     Subject to applicable law, the Warrant Agent and, by acceptance of the
Warrant Certificate and as part of the consideration for the issue of the
Warrants, the Warrantholders hereby waive and release any right, cause of action
or remedy now or hereafter existing in any jurisdiction against any person in
its capacity as an incorporator or any past, present or future shareholder,
director, officer, employee or agent of WorldHeart for the creation and issue of
the Common Shares pursuant to any Warrant or any covenant, agreement,
representation or warranty by WorldHeart herein or in the Warrant Certificates.

                                   ARTICLE 8

                           MEETINGS OF WARRANTHOLDERS

8.1  Amendments

Any term of the Warrants may be amended or waived (including the adjustment
provisions included in this Warrant Indenture) upon the written consent of
WorldHeart and the holders of Warrants representing at least 50% of the number
of Common Shares then issuable upon the exercise of all outstanding Warrants;
provided that (a) any such amendment or waiver must apply to all the Warrants;
and (b) the number of Common Shares issuable upon the exercise of the Warrants,
the Exercise Price and the Expiry Date may not be amended, and the right to
<PAGE>
                                      -26-

exercise the Warrants may not be altered or waived without the written consent
of each Warrantholder.

                                   ARTICLE 9

               SUPPLEMENTAL INDENTURES AND SUCCESSOR CORPORATIONS

9.1  Provision for Supplemental Indentures for Certain Purposes

     From time to time WorldHeart (when authorized by the directors) and the
Warrant Agent may, subject to the provisions hereof, including without
limitation Article 8 hereof, and will when so directed hereby, execute and
deliver by their proper officers, indentures or instruments supplemental hereto,
which thereafter will form part hereof, for any or all of the following
purposes:

     (a)  setting forth any adjustments resulting from the application of the
          provisions of Article 5;

     (b)  adding hereto such additional covenants and enforcement provisions as
          in the opinion of counsel are necessary or advisable, and are not, in
          the opinion of the Warrant Agent relying on the opinion of counsel,
          prejudicial to the rights or interests of the Warrantholders as a
          group;

     (c)  giving effect to any amendment or waiver passed as provided in Article
          8;

     (d)  making such provisions not inconsistent with this Indenture as are
          necessary or desirable with respect to matters or questions arising
          hereunder, and which are not, in the opinion of the Warrant Agent
          relying on the opinion of counsel, prejudicial to the rights or
          interests of the Warrantholders as a group;

     (e)  adding to, deleting or altering the provisions hereof in respect of
          the transfer of Warrants or the exchange of Warrant Certificates, and
          making any modification in the form of the Warrant Certificates
          provided that any such action in the opinion of counsel acceptable to
          the Warrant Agent does not adversely affect the rights of the
          Warrantholder;

     (f)  modifying any provision of this Indenture or relieving WorldHeart from
          any obligation, condition or restriction herein contained, except that
          no such modification or relief will be or become operative or
          effective if in the opinion of the Warrant Agent, relying on the
          opinion of counsel, it would impair any of the rights or interests of
          the Warrantholders or of the Warrant Agent, and the Warrant Agent may
          in its uncontrolled discretion decline to enter into any such
          supplemental indenture which in its opinion will not afford adequate
          protection to the Warrant Agent when it becomes operative; and

     (g)  for any other purpose not inconsistent with the terms of this
          Indenture, including the correction or rectification of any ambiguity,
          defective or inconsistent
<PAGE>
                                      -27-

          provision, error or omission herein, if, in the opinion of the Warrant
          Agent relying on the opinion of counsel, the rights of the Warrant
          Agent and of the Warrantholders, as a group, are not prejudiced
          thereby.

9.2  Successor Corporations

     In the case of the consolidation, amalgamation, arrangement, merger or
transfer of the undertaking or assets of WorldHeart as an entirety, or
substantially as an entirety, to another corporation, the successor corporation
resulting from such consolidation, amalgamation, arrangement, merger or transfer
(if not WorldHeart) will be bound by the provisions hereof and for the due and
punctual performance and observance of each and every covenant and obligation
contained in this Indenture to be performed by WorldHeart and, will as a
condition precedent to any such transaction, agree to succeed to and be
substituted for WorldHeart by supplemental indenture in form satisfactory to the
Warrant Agent and executed and delivered to the Warrant Agent with the same
effect as closely as may be possible as if it had been named herein.

                                   ARTICLE 10

                          CONCERNING THE WARRANT AGENT

10.1 Trust Indenture Legislation

(1) If and to the extent that any provision of this Indenture limits, qualifies
or conflicts with a mandatory requirement of Applicable Legislation, the
mandatory requirement will prevail.

(2) WorldHeart and the Warrant Agent each will at all times in relation to this
Indenture and any action to be taken hereunder observe and comply with and be
entitled to the benefits of Applicable Legislation.

10.2 Warrant Agent's Authority to Carry on Business

The Warrant Agent represents and warrants to WorldHeart that at the date hereof
it is authorized to carry on the business of a trust company in Toronto,
Ontario. If, notwithstanding the provisions of this Section 10.2, it ceases to
be authorized to carry on such business, the validity and enforceability of this
Indenture and the Warrants issued hereunder shall not be affected in any manner
whatsoever by reason only of such event provided that the Warrant Agent, within
30 days after ceasing to be authorized to carry on such business either becomes
so authorized or resigns in the manner and with the effects specified in Section
10.8.

10.3 Rights and Duties of Warrant Agent

(1) In the exercise of the rights and duties prescribed or conferred by the
terms of this Indenture, the Warrant Agent will act honestly and in good faith
with a view to the best interests of the Warrantholders, and will exercise that
degree of care, diligence and skill that a reasonably prudent warrant trustee
would exercise in comparable circumstances. Subject to the foregoing, the
Warrant Agent shall not be bound to give any notice or do or take any act,
action or proceeding by virtue of the powers conferred on it hereby unless and
until it shall have been
<PAGE>
                                      -28-

required so to do under the terms hereof; nor shall the Warrant Agent be
required to take notice of any default hereunder, unless and until notified in
writing of such default, which notice shall distinctly specify the default
desired to be brought to the attention of the Warrant Agent and in the absence
of any such notice the Warrant Agent may for all purposes of this Indenture
conclusively assume that no default has been made in the observance or
performance of any of the representations, warranties, covenants, agreements or
conditions contained therein. Any such notice shall in no way limit any
discretion herein given to the Warrant Agent to determine whether or not the
Warrant Agent shall take action with respect to any default.

(2) No provision of this Indenture will be construed to relieve the Warrant
Agent from liability for its own negligent act, negligent failure to act, wilful
misconduct or bad faith.

(3) The obligation of the Warrant Agent to commence or continue any act, action
or proceeding for the purpose of enforcing any right of the Warrant Agent or the
Warrantholders hereunder is on the condition that, when required by notice to
the Warrantholders by the Warrant Agent, the Warrant Agent is furnished by one
or more Warrantholders with sufficient funds to commence or continue such act,
action or proceeding and indemnity reasonably satisfactory to the Warrant Agent
to protect and hold it harmless against the costs, charges and expenses and
liabilities to be incurred thereby and any loss and damage it may suffer by
reason thereof.

(4) No provision of this Indenture will require the Warrant Agent to expend or
risk its own funds or otherwise incur financial liability in the performance of
any of its duties or in the exercise of any of its rights or powers unless it is
so funded and indemnified.

(5) The Warrant Agent may, before commencing or at any time during the
continuance of any such act, action or proceeding, require the Warrantholders at
whose instance it is acting to deposit with the Warrant Agent the Warrant
Certificates held by them, for which certificates the Warrant Agent will issue
receipts.

(6) Every provision of this Indenture that relieves the Warrant Agent of
liability or entitles it to rely on any evidence submitted to it is subject to
the provisions of Applicable Legislation, and of this Section 10.3.

10.4 Evidence, Experts and Advisers

(1) In addition to the reports, certificates, opinions and other evidence
required by this Indenture, WorldHeart will furnish to the Warrant Agent such
additional evidence of compliance with any provision hereof, and in such form,
as is prescribed by Applicable Legislation or as the Warrant Agent reasonably
requires by written notice to WorldHeart.

(2) In the exercise of any right or duty hereunder the Warrant Agent, if it is
acting in good faith, may act and rely, as to the truth of any statement or the
accuracy of any opinion expressed therein, on any statutory declaration,
opinion, report, certificate or other evidence furnished to the Warrant Agent
pursuant to a provision hereof or of Applicable Legislation or pursuant to a
request of the Warrant Agent, if such evidence complies with Applicable
Legislation and the Warrant Agent examines such evidence and determines that it
complies with the applicable requirements of this Indenture.
<PAGE>
                                      -29-

(3) Whenever Applicable Legislation requires that evidence referred to in
Subsection 10.4(1) be in the form of a statutory declaration, the Warrant Agent
may accept such statutory declaration in lieu of a certificate of WorldHeart
required by any provision hereof.

(4) Any such statutory declaration may be made by any director or officer of
WorldHeart to whom authority is delegated by the board of directors of
WorldHeart from time to time.

(5) The Warrant Agent may act and rely and shall be protected in acting and
relying upon any resolution, certificate, statement, instrument, opinion,
report, notice, request, consent, order, letter, telegram, cablegram or other
paper or document believed by it to be genuine and to have been signed, sent or
presented by or on behalf of the proper party or parties.

(6) Proof of the execution of any document or instrument in writing, including a
Warrantholders' Request, by a Warrantholder may be made by the certificate of a
notary public, or other officer with similar powers, that the person signing
such instrument acknowledged to him the execution thereof, or by an affidavit of
a witness to such execution, or in any other manner that the Warrant Agent
considers adequate.

(7) The Warrant Agent may employ or retain such counsel, accountants, engineers,
appraisers, or other experts or advisers as it reasonably requires for the
purpose of determining and discharging its duties hereunder and may pay
reasonable remuneration for all services so performed by any of them, without
taxation of costs of any counsel, and will not be responsible for any misconduct
or negligence on the part of any of them who has been selected with due care by
the Warrant Agent. Any remuneration so paid by the Warrant Agent shall be repaid
to the Warrant Agent in accordance with Section 6.2.

(8) The Warrant Agent may act and shall be protected in acting and relying in
good faith on the opinion or advice of or information obtained from any counsel,
accountant or other expert or advisor, whether retained or employed by
WorldHeart or by the Warrant Agent, in relation to any matter arising in the
administration of the trusts hereof.

10.5 Documents, Money, Etc. held by Warrant Agent

(1) The Warrant Agent may retain any cash balance held in connection with this
Warrant Indenture and may, but need not, hold the same in its deposit department
or the deposit department of one if its Affiliates; but the Warrant Agent and
its Affiliates shall not be liable to account for any profit to WorldHeart or
any other person or entity other than at a rate, if any, established from time
to time by the Warrant Agent or its Affiliates.

(2) Interest, if any, received by the Warrant Agent in respect of such deposits
will belong to WorldHeart..

10.6 Action by Warrant Agent to Protect Interests

     The Warrant Agent will have power to institute and to maintain such actions
and proceedings as it considers necessary or expedient to protect or enforce its
interests and the interests of the Warrantholders.
<PAGE>
                                      -30-

10.7 Warrant Agent not Required to Give Security

     The Warrant Agent will not be required to give any bond or security in
respect of the performance of the agency created hereby, the execution of the
trusts and powers of this Indenture or otherwise in respect of the premises.

10.8 Protection of Warrant Agent

(1) By way of supplement to the provisions of any law for the time being
relating to trustees or agents, it is expressly declared and agreed that:

     (a)  the Warrant Agent will not be liable for or by reason of, or required
          to substantiate, any statement of fact or recital in this Indenture or
          in the Warrant Certificates (except the representation contained in
          Section 10.10 or in the certificate of the Warrant Agent on the
          Warrant Certificates), but all such statements or recitals are and
          will be deemed to be made by WorldHeart;

     (b)  nothing herein contained will impose on the Warrant Agent any
          obligation to see to, or to require evidence of, the registration or
          filing (or renewal thereof) of this Indenture or any instrument
          ancillary or supplemental hereto;

     (c)  subject to Section 10.10 the Warrant Agent will not be bound to give
          notice to any person of the execution hereof;

     (d)  the Warrant Agent will not incur any liability or responsibility
          whatsoever or be in any way responsible for the consequence of any
          breach by WorldHeart of any obligation herein contained or of any act
          of any director, officer, employee or agent of WorldHeart; and

     (e)  the Warrant Agent shall not be liable or accountable for any loss or
          damage whatsoever to any person caused by the performance or failure
          by it to perform its responsibilities under this Indenture save only
          to the extent that such loss or damage is attributable to the
          negligence, wilful misconduct or bad faith of the Warrant Agent.

(2) WorldHeart indemnifies the Warrant Agent and its directors, officers,
employees and agents and saves them harmless from all liabilities, losses,
claims, demands, suits, damages, costs and actions which may be brought against
or suffered by it arising out of or connected with the performance by it of its
duties hereunder including any and all legal fees and disbursements except to
the extent that such liabilities, suits, damages, costs and actions are
attributable to the negligence, wilful misconduct or bad faith of the Warrant
Agent. This provision shall survive the resignation or termination or discharge
of the Warrant Agent or the termination of the Indenture.
<PAGE>
                                      -31-

10.9 Replacement of Warrant Agent

(1) The Warrant Agent may resign its trust hereunder and be discharged from all
further duties and liabilities hereunder, except as provided in this Section, by
giving to WorldHeart and the Warrantholders not less than 30 business days'
notice in writing or, if a new Warrant Agent has been appointed, such shorter
notice as WorldHeart accepts as sufficient.

(2) The Warrantholders pursuant to the provisions of Article 8 hereof may at any
time remove the Warrant Agent and appoint a new Warrant Agent.

(3) If the Warrant Agent so resigns or is so removed or is dissolved, becomes
bankrupt, goes into liquidation or otherwise becomes incapable of acting
hereunder, WorldHeart will forthwith appoint a new Warrant Agent unless a new
Warrant Agent has already been appointed by the Warrantholders.

(4) Failing such appointment by WorldHeart, the retiring Warrant Agent or any
Warrantholder at the expense of WorldHeart may apply to the Ontario Court of
Justice (General Division) (the "Court") on such notice as the Court directs,
for the appointment of a new Warrant Agent, at the expense of WorldHeart.

(5) Any new Warrant Agent so appointed by WorldHeart or by the Court will be
subject to removal as aforesaid by the Warrantholders.

(6) Any new Warrant Agent appointed under any provision of this Section must be
a corporation authorized to carry on the business of a trust company in Ontario
and, if required by the Applicable Legislation of any other province, in such
other province.

(7) On any such appointment the new Warrant Agent will be vested with the same
powers, rights, duties and responsibilities as if it had been originally named
herein as Warrant Agent without any further assurance, conveyance, act or deed,
but there will be immediately executed, at the expense of WorldHeart, all such
conveyances or other instruments as, in the opinion of counsel, are necessary or
advisable for the purpose of assuring such powers, rights, duties and
responsibilities to the new Warrant Agent and provided that, upon any
resignation or termination of the Warrant Agent and appointment of a successor
Warrant Agent, such successor Warrant Agent shall have executed an appropriate
instrument accepting such appointment and, at the request of WorldHeart, the
predecessor Warrant Agent, upon payment of its outstanding remuneration and
expenses, shall execute and deliver to the successor Warrant Agent an
appropriate instrument transferring to such successor Warrant Agent all rights
and powers of the Warrant Agent hereunder.

(8) On the appointment of a new Warrant Agent, WorldHeart will promptly give
notice thereof to the Warrantholders.

(9) A corporation into or with which the Warrant Agent is merged or consolidated
or amalgamated, or a corporation succeeding to the trust business of the Warrant
Agent, will be the successor to the Warrant Agent hereunder without any further
act on its part or on the part of any
<PAGE>
                                      -32-

party hereto if such corporation would be eligible for appointment as a new
Warrant Agent under Subsection 10.8(6).

(10) A Warrant Certificate certified but not delivered by a predecessor Warrant
Agent may be delivered by the new or successor Warrant Agent in the name of the
predecessor Warrant Agent or successor Warrant Agent.

10.10 Conflict of Interest

     The Warrant Agent represents to WorldHeart that at the time of the
execution and delivery hereof no material conflict of interest exists between
its role as a fiduciary hereunder and its role in any other capacity and if a
material conflict of interest arises hereafter it will, within 90 business days
after ascertaining that it has such material conflict of interest, either
eliminate the conflict of interest or resign its trust hereunder.

     If any such material conflict of interest exists or hereafter shall exist,
the validity and enforceability of this Indenture and of the Warrants shall not
be affected in any manner whatsoever by reason thereof.

     The Warrant Agent, in its personal or any other capacity, may buy, lend
upon and deal in securities of WorldHeart and generally may contract and enter
into financial transactions with WorldHeart without being liable to account for
any profit made thereby.

10.11 Warrant Agent Not Appointed Receiver

     The Warrant Agent and any person related to the Warrant Agent will not be
appointed a receiver or receiver and manager or liquidator of all or any part of
the assets or undertaking of WorldHeart.

10.12 Acceptance of Trusts

     The Warrant Agent hereby accepts the trusts in this Indenture declared and
provided for and agrees to perform them on the terms and conditions herein set
forth.

                                   ARTICLE 11

                                     GENERAL

11.1 Notice to WorldHeart and Warrant Agent

(1) Unless herein otherwise expressly provided, a notice to be given hereunder
to WorldHeart or the Warrant Agent will be validly given if delivered or if sent
by first class mail, postage prepaid, or if sent by facsimile transmission
(receipt of such transmission is confirmed in writing):
<PAGE>
                                      -33-

     (a)  If to WorldHeart:

                  World Heart Corporation
                  1 Laser Street
                  Ottawa, ON
                  K2E 7V1

                  Attention:       Chief Financial Officer

                  Facsimile:       (613) 723-8522

     (b)  If to the Warrant Agent:

                  CIBC Mellon Trust Company
                  320 Bay Street, P.O. Box 1
                  Toronto, ON
                  M5H 4A6

                  Attention:       Vice President, Client Services

                  Facsimile:       (416) 643-5570

and any such notice delivered or sent in accordance with the foregoing will be
deemed to have been received on the date of delivery or facsimile transmission
or, if mailed, on the fifth business day following the day of the mailing of the
notice.

(2) WorldHeart or the Warrant Agent, as the case may be, may from time to time
notify the other in the manner provided in Subsection 11.1(1) of a change of
address which, from the effective date of such notice and until changed by like
notice, will be the address of WorldHeart or the Warrant Agent, as the case may
be, for all purposes of this Indenture.

(3) If, by reason of a strike, lockout or other work stoppage, actual or
threatened, involving Canadian postal employees, a notice to be given to the
Warrant Agent or to WorldHeart hereunder could reasonably be considered unlikely
to reach or likely to be delayed in reaching its destination, the notice will be
valid and effective only if it is delivered to an officer of the party to which
it is addressed or if it is delivered to such party at the appropriate address
provided in Subsection 11.1(1) by confirmed facsimile transmission and any
notice deliver in accordance with the foregoing will be deemed to have been
received on the date of delivery to such officer or if delivered by such
facsimile, on the first business day following the date of the sending of the
notice.

11.2 Notice to Warrantholders

(1) Unless herein otherwise expressly provided, a notice to be given hereunder
to Warrantholders will be deemed to be validly given if the notice is sent by
ordinary surface or air mail, postage prepaid, addressed to the Warrantholders
or delivered (or so mailed to certain Warrantholders and so delivered to the
other Warrantholders) at their respective addresses
<PAGE>
                                      -34-

appearing on any of the registers of holders described in Section 3.1 provided,
however, that if, by reason of a strike, lockout or other work stoppage, actual
or threatened, involving Canadian postal employers, the notice could reasonably
be considered unlikely to reach or likely to be delayed in reaching its
destination, the notice will be valid and effective only if it is so delivered
or is given by publication twice in the Report on Business section in the
national edition of The Globe and Mail newspaper.

(2) A notice so given by mail or so delivered will be deemed to have been given
on the fifth business day after it has been mailed or on the day which it has
been delivered, as the case may be, and a notice so given by publication will be
deemed to have been given on the day on which it has been published as required.
In determining under any provision hereof the date when notice of a meeting or
other event must be given, the date of giving notice will be included and the
date of the meeting or other event will be excluded. Accidental error or
omission in giving notice or accidental failure to mail notice to any
Warrantholder will not invalidate any action or proceeding founded thereon.

11.3 Satisfaction and Discharge of Indenture

     On the earlier of:

     (a)  the date by which there has been delivered to the Warrant Agent for
          exercise or surrender for cancellation all Warrant Certificates
          theretofore certified hereunder; or

     (b)  the Expiry Time;

and if all certificates representing Common Shares required to be issued in
compliance with the provisions hereof have been issued and delivered hereunder
or to the Warrant Agent in accordance with such provisions, this Indenture will
cease to be of further effect and, on demand of and at the cost and expense of
WorldHeart and on delivery to the Warrant Agent of a certificate of WorldHeart
stating that all conditions precedent to the satisfaction and discharge of this
Indenture have been complied with and on payment to the Warrant Agent of the
fees and other remuneration payable to the Warrant Agent, the Warrant Agent will
execute proper instruments acknowledging satisfaction of and discharging this
Indenture.

11.4 Sole Benefit of Parties and Warrantholders

     Nothing in this Indenture or the Warrant Certificates, expressed or
implied, will give or be construed to give to any person other than the parties
hereto and the Warrantholders, as the case may be, any legal or equitable right,
remedy or claim under this Indenture or the Warrant Certificates, or under any
covenant or provision herein or therein contained, all such covenants and
provisions being for the sole benefit of the parties hereto and the
Warrantholders.
<PAGE>
                                      -35-

11.5 Discretion of Directors

     Any matter provided herein to be determined by the directors of WorldHeart
will be determined by the directors of WorldHeart in their sole good faith
discretion, and a determination so made will be conclusive.

11.6 Counterparts and Formal Date

     This Indenture may be executed in several counterparts, each of which when
so executed will be deemed to be an original and such counterparts together will
constitute one and the same instrument and notwithstanding the date of their
execution will be deemed to be dated as of the Effective Date.

11.7 Language

     The parties hereby request that this Indenture and any related documents be
drawn up and executed only in the English language. Les parties demandent par
les presentes que la presente convention ainsi que tous les documents y
afferents soient rediges et executes en langue anglaise seulement.

11.8 Assignment

     Subject to Section 9.2 hereof, neither this Indenture nor any right,
interest or obligation hereunder may be assigned by either party without the
prior written consent of the other party and any purported assignment of this
Indenture which does not comply with this Section 11.8 shall be considered null
and void.

11.9 Benefit of the Agreement

     This Indenture will enure to the benefit of and be binding upon the
respective successors and permitted assigns of the parties hereto.

11.10 Further Assurances

     The parties will from time to time execute and deliver all such further
documents and instruments and do all acts and things as the other party may,
either before or after the Effective Date, reasonably require to effectively
carry out or better evidence the full intent or meaning of this Indenture.
<PAGE>
     IN WITNESS WHEREOF the parties hereto have caused their respective
corporate seals to be hereunto affixed attested by their signatures.

                             WORLD HEART CORPORATION

                             By:   /s/ Mark Goudie
                                   ------------------------------------
                                   Name:    Mark Goudie
                                   Title:   Chief Financial Officer

                             CIBC MELLON TRUST COMPANY

                             By:   /s/ Bruce Cornish
                                   --------------------------------------
                                    Name:    Bruce Cornish
                                    Title:   Authorized Signatory

                             By:   /s/ Warren Jansen
                                   Name:     Warren Jansen
                                   Title:   Authorized Signatory
<PAGE>
SCHEDULE A

FORM OF WARRANT

[Legends for Warrants issued to US purchasers]]

THE HOLDER, BY ITS ACCEPTANCE OF THIS SECURITY, REPRESENTS, ACKNOWLEDGES, AND
AGREES THAT IT WILL NOT AND WILL NOT BE ENTITLED TO, DIRECTLY OR INDIRECTLY,
SELL OR TRANSFER THE SECURITIES INTO CANADA OR TO RESIDENTS OF CANADA, EXCEPT IN
COMPLIANCE WITH APPLICABLE CANADIAN SECURITIES LAWS. NO SALE OR TRANSFER INTO
CANADA OR TO A CANADIAN RESIDENT WILL BE REGISTERED BY WORLD HEART CORPORATION'S
TRANSFER AGENT AND ANY ATTEMPT TO EFFECT SUCH A TRANSFER IS INVALID UNLESS MADE
IN COMPLIANCE WITH THE ABOVE-NOTED RESTRICTIONS.

UNLESS PERMITTED UNDER CANADIAN SECURITIES LEGISLATION, THE HOLDER OF THE
SECURITIES SHALL NOT TRADE THE SECURITIES BEFORE JANUARY 17, 2005.

THE SECURITIES REPRESENTED HEREBY (AND THE SECURITIES ISSUED UPON EXERCISE
HEREOF) HAVE NOT BEEN REGISTERED UNDER THE UNITED STATES SECURITIES ACT OF 1933,
AS AMENDED (THE "U.S. SECURITIES ACT") OR THE SECURITIES LAWS OF ANY STATE OF
THE UNITED STATES. THE HOLDER HEREOF, BY PURCHASING SUCH SECURITIES, AGREES FOR
THE BENEFIT OF THE CORPORATION THAT SUCH SECURITIES MAY BE OFFERED, SOLD,
PLEDGED OR OTHERWISE TRANSFERRED ONLY (A) TO THE CORPORATION, OR (B) OUTSIDE THE
UNITED STATES IN ACCORDANCE WITH RULE 903 OR 904 OF REGULATION S UNDER THE U.S.
SECURITIES ACT, IF APPLICABLE, OR (C) INSIDE THE UNITED STATES (1) PURSUANT TO
THE EXEMPTION FROM THE REGISTRATION REQUIREMENTS UNDER THE U.S. SECURITIES ACT
PROVIDED BY RULE 144 THEREUNDER, IF AVAILABLE, AND IN ACCORDANCE WITH APPLICABLE
STATE SECURITIES LAW OR (2) IN A TRANSACTION THAT DOES NOT OTHERWISE REQUIRE
REGISTRATION UNDER THE U.S. SECURITIES ACT OR ANY APPLICABLE STATE SECURITIES
LAW, PROVIDED THE HOLDER HAS FURNISHED TO THE CORPORATION AN OPINION OF COUNSEL
OF RECOGNIZED STANDING TO THAT EFFECT IN FORM AND SUBSTANCE REASONABLY
SATISFACTORY TO THE CORPORATION OR (3) PURSUANT TO A REGISTRATION STATEMENT
PURSUANT TO THE U.S. SECURITIES ACT.

[Legends for Warrants issued to Canadian purchasers]

UNLESS PERMITTED UNDER CANADIAN SECURITIES LEGISLATION, THE HOLDER OF THE
SECURITIES SHALL NOT TRADE THE SECURITIES BEFORE JANUARY 17, 2005.

THE SECURITIES REPRESENTED HEREBY (AND THE SECURITIES ISSUED UPON EXERCISE
HEREOF) HAVE NOT BEEN REGISTERED UNDER THE UNITED STATES SECURITIES ACT OF 1933,
AS AMENDED (THE "U.S. SECURITIES ACT") OR THE SECURITIES LAWS OF ANY STATE OF
THE UNITED STATES. THE HOLDER HEREOF, BY PURCHASING SUCH SECURITIES, AGREES FOR
THE BENEFIT OF THE CORPORATION THAT SUCH SECURITIES MAY BE OFFERED, SOLD,
PLEDGED OR OTHERWISE TRANSFERRED ONLY (A) TO THE CORPORATION, OR (B) OUTSIDE THE
UNITED STATES IN ACCORDANCE WITH RULE 903 OR 904 OF REGULATION S UNDER THE U.S.
SECURITIES ACT, IF APPLICABLE, OR (C) INSIDE THE UNITED STATES (1) PURSUANT TO
THE EXEMPTION FROM THE REGISTRATION REQUIREMENTS UNDER THE U.S. SECURITIES ACT
PROVIDED BY RULE 144 THEREUNDER, IF AVAILABLE, AND IN ACCORDANCE WITH APPLICABLE
STATE SECURITIES LAW OR (2) IN A TRANSACTION THAT DOES NOT OTHERWISE REQUIRE
REGISTRATION UNDER THE U.S. SECURITIES ACT OR ANY APPLICABLE STATE SECURITIES
LAW, PROVIDED THE HOLDER HAS FURNISHED TO THE CORPORATION AN OPINION OF COUNSEL
OF RECOGNIZED STANDING TO THAT EFFECT IN FORM AND SUBSTANCE REASONABLY
SATISFACTORY TO THE CORPORATION OR (3) PURSUANT TO A REGISTRATION STATEMENT
PURSUANT TO THE U.S. SECURITIES ACT.
<PAGE>
                                      -2-

Certificate No.:                                   No. of Warrants:
                ------------                                        ------------

                                    WARRANTS
                             Exercisable to Acquire
                                  Common Shares
                                       of
                             WORLD HEART CORPORATION
          (Incorporated under the Business Corporations Act (Ontario))

THIS IS TO CERTIFY THAT, for value received,
                                            -----------------------------------
(the "holder") is the registered holder of the number of Warrants ("Warrants")
of World Heart Corporation ("WorldHeart") specified above and for each Warrant
held is thereby entitled, to be issued fully paid and non-assessable common
shares ("Common Shares") in the capital of WorldHeart, on the basis of one
Common Share for each such Warrant, subject to the limitation referred to below,
by surrendering to CIBC Mellon Trust Company (the "Warrant Agent") at its
principal transfer office in Toronto, Ontario during the exercise period
hereinafter referred to, a certified cheque or bank draft made payable to
WorldHeart in the amount of the Exercise Price as hereinafter determined in
respect of each Common Share to be issued, this Warrant Certificate and a notice
of exercise in the form set forth in Appendix 1 annexed hereto duly completed
and executed.

Capitalized terms which are not otherwise defined herein shall have the same
meaning as in the Warrant Indenture (which indenture, together with all
instruments supplemental or ancillary thereto, is herein referred to as the
"Warrant Indenture") dated as of September 15, 2004 between WorldHeart and the
Warrant Agent, as warrant agent.

Surrender of this Warrant Certificate will be deemed to have been effected only
on personal delivery thereof to, or, if sent by mail or other means of
transmission, on actual receipt thereof by, the Warrant Agent at the office
specified above.

This Warrant Certificate evidences Warrants of WorldHeart issued or issuable
under the provisions of the Warrant Indenture. Reference is made to the Warrant
Indenture for particulars of the rights of the holders of the Warrants and of
WorldHeart and of the Warrant Agent in respect thereof and of the terms and
conditions upon which the Warrants are issued and held, all to the same effect
as if the provisions of the Warrant Indenture were herein set forth, to all of
which the holder, by acceptance hereof, assents. To the extent of any
inconsistency between the terms of the Warrant Indenture and the terms of this
Warrant Certificate, the terms of the Warrant Indenture shall prevail.
WorldHeart will furnish to the holder, on request and upon payment of a
reasonable charge for photocopying and postage, a copy of the Warrant Indenture.

The Warrants evidenced by this Warrant Certificate may be exercised by the
holder until 5:00 p.m. (Toronto time) on the date that is 60 months from the
Effective Date.
<PAGE>
                                      -3-

On and after the date of any exercise of the Warrants evidenced by this Warrant
Certificate, the holder will have no rights hereunder except to receive
certificates representing the Common Shares thereby issued to him upon delivery
of: (i) a certified cheque or bank draft payable to WorldHeart in the amount of
US$1.55, unless such price has been adjusted in accordance with the provisions
of the Warrant Indenture in which case it shall be the adjusted price in effect
at the applicable time (the "Exercise Price") in respect of each Common Share to
be issued, (ii) this Warrant Certificate, and (iii) duly completed Notice of
Exercise as set out on Appendix 1 to the Warrant Agent at its principal office
in Toronto, Ontario. After the Expiry Time, all rights under any unexercised
Warrant evidenced hereby will wholly cease and terminate and this Warrant
Certificate will be void.

WorldHeart will not be obligated to issue any fraction of a Common Share on the
exercise of any Warrants. To the extent that a holder of Warrants would
otherwise have been entitled to receive, on the exercise of the Warrants, a
fraction of a Common Share such rate may only be exercised in respect of such
fraction in connection with another Warrant or Warrants which in the aggregate
entitle the holder to receive a whole number of Common Shares. If a
Warrantholder is not able to combine Warrants so as to be entitled to acquire a
whole number of Common Shares the number of Common Shares which such
Warrantholder is entitled to receive shall be rounded down to the prior whole
number.

The Warrant Indenture provides for adjustments to the number of Common Shares
issuable and the Exercise Price in certain events set forth therein.

No Common Share will be issued pursuant to any Warrant if the issuance of such
security would constitute a violation of the securities laws of any applicable
jurisdiction.

The Warrant Indenture contains provisions making binding on all holders of
Warrants outstanding thereunder certain amendments or waivers approved by 50% of
the holders of all Warrants and by WorldHeart.

On presentation at the principal office of the Warrant Agent in Toronto,
Ontario, subject to the provisions of the Warrant Indenture and on compliance
with the reasonable requirements of the Warrant Agent, one or more Warrant
Certificates may be exchanged for one or more Warrant Certificates of different
denominations evidencing in the aggregate the same number of Warrants as the
Warrant Certificate or Warrant Certificates being exchanged, and such holder
shall pay the reasonable cost thereof.

The Warrants evidenced by this Warrant Certificate may only be transferred, upon
compliance with the conditions prescribed in the Warrant Indenture, on the
register of transfers to be kept at the principal office of the Warrant Agent in
Toronto, Ontario by the holder, or its officers, employees, members, partners
and managers, or the holder's executors, administrators or other legal
representatives or his or its or their respective attorney duly appointed by an
instrument in writing in form and execution satisfactory to the Warrant Agent,
and a written acknowledgement by the transferee substantially in the form of
Appendix 3 annexed hereto or otherwise in form satisfactory to the Warrant Agent
executed by the transferee and subject to compliance with certain other terms of
the Warrant Indenture, and upon compliance with such requirements and
<PAGE>
                                      -4-

such other reasonable requirements as the Warrant Agent may prescribe, such
transfer will be duly noted on such register of transfers by the Warrant Agent.
Notwithstanding the foregoing, WorldHeart will be entitled, and may direct the
Warrant Agent, to refuse to record any transfer of any Warrant on such register
if such transfer would constitute a violation of the securities laws of any
applicable jurisdiction.

The holding of this Warrant Certificate will not constitute the holder as a
shareholder of WorldHeart or entitle him or it to any right or interest as a
shareholder except as otherwise provided in the Warrant Indenture.

This Warrant Certificate will not be valid for any purpose until it has been
certified by or on behalf of the Warrant Agent for the time being under the
Warrant Indenture. Time will be of the essence hereof.

The Warrants and the Common Shares issuable upon the exercise of the Warrants
will be subject to statutory resale restrictions under the applicable securities
legislation in Canada and the United States.

IN WITNESS WHEREOF WorldHeart has caused this Warrant Certificate to be signed
by its officer duly authorized in that behalf as of September 15, 2004.

                                   WORLD HEART CORPORATION
                             By:
                                   ---------------------------------------------
                                   Name:    D. Mark Goudie
                                   Title:   Vice President, Finance and
                                            Chief Financial Officer

This Warrant Certificate is one of the Warrant Certificates referred to in the
Warrant Indenture within mentioned.

                                   CIBC MELLON TRUST COMPANY, as Warrant Agent
                             By:
                                   ---------------------------------------------
                                   Authorized Signing Officer
<PAGE>
                                   APPENDIX 1

                               NOTICE OF EXERCISE

To:        WORLD HEART CORPORATION
And To:    CIBC MELLON TRUST COMPANY

The undersigned holder of the Warrants evidenced by the within Warrant
Certificate hereby exercises its right to be issued Common Shares of World Heart
Corporation (or such other securities or property to which such exercise
entitles him in lieu thereof or in addition thereto under the provisions of the
Warrant Indenture mentioned in such Warrant Certificate) that are issuable upon
the exercise of such Warrants, on the terms specified in such Warrant
Certificate and Warrant Indenture and in connection therewith has enclosed a
certified cheque or bank draft payable to World Heart Corporation in an amount
equal to US$1.55 (or price as adjusted) in respect of each Common Share to be
issued.

The undersigned hereby irrevocably directs that the said Common Shares be
issued, registered and delivered as follows:

Name(s) in Full        Address(es) in full, Account         Number(s) of Common
                       No., S.I.N.                          Shares
                       [Note US residents must
                       include their Taxpayer
                       Identification Number]

---------------------  ---------------------------    --------------------------

---------------------  ---------------------------    --------------------------
This Notice of Exercise must be accompanied by a Declaration substantially in
the form of Exhibit 1 to the Warrant Certificate duly completed and executed by
the holder if the Warrant Certificate is to be transferred to or exercised by a
non-U.S. Person.

(Please print full name in which certificates for Common Shares are to be
issued. If any securities are to be issued to a person or persons other than the
holder, the holder must pay to the Warrant Agent all exigible transfer taxes or
other government charges and sign the Form of Transfer.)

DATED this                  day of           ,             .
           ----------------        ----------  ------------

                                               )  ------------------------
                                               )  Signature of Registered Holder
                                               )
-----------------------------------------------)  ------------------------
Witness                                           Name of Registered Holder
Note:    The name of the Registered Holder of this Notice of Exercise must be
         the same as the name appearing on the face page of the Warrant
         Certificate to which this Appendix is attached.

|    |   Please check if the Common Share certificates are to be delivered at
         the office where this Warrant Certificate is surrendered, failing which
         such certificates will be mailed.

         Certificates will be delivered or mailed as soon as practicable after
         the due surrender of this Warrant Certificate to which this Appendix is
         attached in accordance with the terms of the Warrant Indenture.

Manner of Delivery

If this Notice of Exercise is delivered by mail: CIBC Mellon Trust Company, P.O.
Box 1036 Adelaide St. Postal Station, Toronto, Ontario M5C 2K4.

If this Notice of Exercise is delivered by hand or courier: CIBC Mellon Trust
Company, 199 Bay Street, Commerce Court West, Securities Level, Toronto Ontario,
M5L 1G9. Attention: Courier Window
<PAGE>
                                      -2-

EXHIBIT 1

DECLARATION

TO:    CIBC Mellon Trust Company

The undersigned (1) acknowledges that the
transfer to the undersigned of
                              -------------------------------------------------
 Warrants of World Heart Corporation, represented by certificate number(s)
                              -------------------------------------------------
to which this declaration relates (the "Warrant Certificates"), is being made
in reliance on and in compliance with Rule 903 or 904 of Regulation S under the
United States Securities Act of 1933, as amended (the "U.S. Securities Act"),
and (2) certifies that (a) it is not an "affiliate" (as defined in Rule 405
under the U.S. Securities Act) of World Heart Corporation, (b) it is not a "U.S.
Person" as that term is defined in Regulation S under the U.S. Securities Act,
and (c) it is not a "dealer" as defined in section 2(12) of the U.S. Securities
Act or a person receiving a selling concession, fee or other remuneration in
respect of the Warrant Certificate(s); or, in connection with the exercise or
deemed exercise of the Warrant Certificate(s), the undersigned certifies that it
is not a "U.S. Person", nor is it exercising the Warrant Certificate(s) on
behalf of a "U.S. Person", as that term is defined in Regulation S under the
U.S. Securities Act.

DATED this        day of           , 200        .

                                   --------------------------------------------
                                   Name:
                                   Title:

Manner of Delivery

If this Declaration is delivered by mail: CIBC Mellon Trust Company, P.O. Box
1036 Adelaide St. Postal Station, Toronto, Ontario M5C 2K4.

If this Declaration is delivered by hand or courier: CIBC Mellon Trust Company,
199 Bay Street, Commerce Court West, Securities Level, Toronto Ontario, M5L 1G9.
Attention: Courier Window
<PAGE>
                                      -3-

                                   APPENDIX 2

                                FORM OF TRANSFER

Any transfer of Warrants will require compliance with applicable securities
legislation. Transferors and transferees are urged to contact legal counsel
before effecting any such transfers.

FOR VALUE RECEIVED the undersigned hereby sells, assigns and transfers to

                  Name:
                             -----------------------------------

                  Address:
                             -----------------------------------

                             -----------------------------------

(such person, the "Transferee")             Warrants of World Heart Corporation
                               ------------
("WorldHeart") registered in the name of the undersigned on the records of
WorldHeart maintained by CIBC Mellon Trust Company represented by the attached
Warrant Certificate and does hereby appoint as its attorney with full power of a
substitution to transfer the Warrants on the appropriate register of the Warrant
Agent.

The undersigned confirms that the transfers are made in compliance with all
applicable securities legislation and requirements of regulatory authorities
including without limitation any undertaking given to the Toronto Stock
Exchange.

If the sale evidenced hereby is being made to a U.S. Person (as such term is
defined in Regulation S to the United States Securities Act of 1933 (the "1933
Act"), the undersigned by the execution of this form of transfer hereby
certifies that such sale does not require registration of the Warrants being
transferred hereby under the 1933 Act and tenders herewith evidence satisfactory
to WorldHeart to such effect.

DATED this                 day of                ,        .
           ----------------       ---------------  -------

                                              )     --------------------------
                                              )      Signature of Transferor
----------------------------------------------
                                              )     --------------------------
                                              )      Name of Transferor
Signature of Transferor must be guaranteed
by a Canadian chartered bank, a major
Canadian trust company or by a Medallion
signature guarantee from a member of a
recognized signature Medallion program

Manner of Delivery

If this Form of Transfer is delivered by mail: CIBC Mellon Trust Company, P.O.
Box 1036 Adelaide St. Postal Station, Toronto, Ontario M5C 2K4.

If this Form of Transfer is delivered by hand or courier: CIBC Mellon Trust
Company, 199 Bay Street, Commerce Court West, Securities Level, Toronto Ontario,
M5L 1G9. Attention: Courier Window
<PAGE>
                                      -4-

                                   APPENDIX 3

                          ACKNOWLEDGEMENT OF TRANSFEREE

TO:        [Name of Transferor]

           - and -

           World Heart Corporation ("WorldHeart")

           - and -

           CIBC Mellon Trust Company (the "Warrant Agent")

The undersigned transferee of           Warrants of World Heart Corporation
                              ---------
hereby (i) acknowledges that such Warrants are subject to the terms, conditions
and provisions of a Warrant Indenture made as of September 15, 2004 (the
"Indenture") between WorldHeart and the Warrant Agent.

DATED the       day of              ,          .
         ------        -------------  ---------

                                   ---------------------------------------------
                                   Print Name of Transferee

                                   By:
                                         ---------------------------------------
                                         Signature

                                   ---------------------------------------------
                                   Office or Title

                                   ---------------------------------------------

                                   ---------------------------------------------
                                   Address of Transferee

Manner of Delivery

If this Acknowledgement of Transferee is delivered by mail: CIBC Mellon Trust
Company, P.O. Box 1036 Adelaide St. Postal Station, Toronto, Ontario M5C 2K4.

If this Acknowledgement of Transferee is delivered by hand or courier: CIBC
Mellon Trust Company, 199 Bay Street, Commerce Court West, Securities Level,
Toronto Ontario, M5L 1G9. Attention: Courier Window

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