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                                                                     Exhibit 4.1

                             ANTIDILUTION AGREEMENT

     THIS ANTIDILUTION AGREEMENT is entered into as of September 26, 2002 by and
between Silicon Valley Bank ("Purchaser") and Cambridge Heart, Inc., a Delaware
corporation (the "Company").

                                    RECITALS

     A.   Concurrently with the execution of this Antidilution Agreement, the
Purchaser is acquiring from the Company a Warrant to Purchase Stock (the
"Warrant") pursuant to which Purchaser has the right to acquire from the Company
the Shares (as defined in the Warrant).

     B.   By this Antidilution Agreement, the Purchaser and the Company desire
to set forth the adjustments to the number of Shares issuable upon exercise of
the Warrant and the Exercise Price therefor as a result of a Diluting Issuance
(as defined below).

     C.   Capitalized terms used herein and not otherwise defined shall have the
respective meanings set forth in the Warrant.

     NOW, THEREFORE, in consideration of the mutual promises, covenants and
conditions hereinafter set forth, the parties hereto mutually agree as follows:

          1.     DEFINITIONS. As used in this Antidilution Agreement, the
following terms have the following respective meanings:

                 (a)    "Option" means any right, option, or warrant to
subscribe for, purchase, or otherwise acquire Common Stock or Convertible
Securities.

                 (b)    "Convertible Securities" means any evidences of
indebtedness, shares of stock, or other securities directly or indirectly
convertible into or exchangeable for Common Stock.

                 (c)    "Issue" means to grant, issue, sell, assume, or fix a
record date for determining persons entitled to receive, any security (including
Options), whichever of the foregoing is the first to occur.

                 (d)    "Additional Common Shares" means all Common Stock
(including reissued shares) Issued (or deemed to be issued pursuant to Section
2) after the original issue date of the Warrant and prior to the second
anniversary of the original issue date of the Warrant. Additional Common Shares
does not include, however, (i) any Common Stock Issued in a transaction
described in Sections 2.1 and 2.2 of the Warrant; (ii) any Common Stock Issued
upon conversion of Options and Convertible Securities outstanding as of the
original issue date of the Warrant; (iii) the Shares; (iv) any Common Stock,
Options or Convertible Securities Issued in connection with a bona fide
strategic business partnership or acquisition transaction approved by the Board
of Directors of the

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Company, or (v) Common Stock, Options or Convertible Securities Issued to
employees or directors of, or consultants to, the Company pursuant to a stock
option plan, agreement or arrangement now existing or hereafter implemented
approved by the Board of Directors of the Company.

          2.     DEEMED ISSUANCE OF ADDITIONAL COMMON SHARES. The shares of
Common Stock ultimately issuable upon exercise of an Option (including the
shares of Common Stock ultimately issuable upon conversion or exercise of a
Convertible Security issuable pursuant to an Option) are deemed to be Issued
when the Option is Issued. The shares of Common Stock ultimately issuable upon
conversion or exercise of a Convertible Security (other than a Convertible
Security Issued pursuant to an Option) shall be deemed Issued upon Issuance of
the Convertible Security. The maximum amount of Common Stock issuable is
determined without regard to any future adjustments permitted under the
instrument creating the Options or Convertible Securities.

          3.     ADJUSTMENT OF WARRANT PRICE FOR DILUTING ISSUANCES.

                 3.1    WEIGHTED AVERAGE ADJUSTMENT. If the Company issues
Additional Common Shares after the original issue date of the Warrant and the
consideration per Additional Common Share (determined pursuant to Section 9
below) is less than the Exercise Price in effect immediately before such Issue
(a "Diluting Issuance"), the Exercise Price shall be reduced, concurrently with
such Issue, to a price (calculated to the nearest hundredth of a cent)
determined by multiplying the Exercise Price by a fraction:

                 (a)    the numerator of which is the number of shares of Common
Stock outstanding immediately before such Issue plus the number of shares of
Common Stock that the aggregate consideration received by the Company for the
Additional Common Shares would purchase at the Exercise Price in effect
immediately before such Issue, and

                 (b)    the denominator of which is the number of shares of
Common Stock outstanding immediately before such Issue plus the number of such
Additional Common Shares.

                 3.2    ADJUSTMENT TO NUMBER OF SHARES. Upon each adjustment of
the Exercise Price, the number of Shares issuable upon exercise of the Warrant
shall be increased to equal the quotient obtained by dividing (a) the product
resulting from multiplying (i) the number of Shares issuable upon exercise of
the Warrant and (ii) the Exercise Price, in each case as in effect immediately
before such adjustment, by (b) the adjusted Exercise Price.

                 3.3    SECURITIES DEEMED OUTSTANDING. For the purpose of this
Section 3, all securities issuable upon exercise of any outstanding Convertible
Securities or Options, warrants, or other rights to acquire securities of the
Company shall be deemed to be outstanding.

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                 3.4    MINIMUM ADJUSTMENT OF EXERCISE PRICE. Notwithstanding
the foregoing, the applicable Exercise Price shall not be reduced if the amount
of such reduction would be less than $0.05, but any such amount shall be carried
forward and reduction with respect thereto made at the time of, and together
with, any subsequent reduction which, together with such amount and any other
amount or amounts so carried forward, shall aggregate $0.05 or more.

          4.     NO ADJUSTMENT FOR ISSUANCES FOLLOWING DEEMED ISSUANCES. No
adjustment to the Exercise Price shall be made upon the exercise of Options or
conversion of Convertible Securities.

          5.     ADJUSTMENT FOLLOWING CHANGES IN TERMS OF OPTIONS OR CONVERTIBLE
SECURITIES. If the consideration payable to, or the amount of Common Stock
Issuable by, the Company increases or decreases, respectively, pursuant to the
terms of any outstanding Options or Convertible Securities, the Exercise Price
shall be recomputed to reflect such increase or decrease. The recomputation
shall be made as of the time of the Issuance of the Options or Convertible
Securities. Any changes in the Exercise Price that occurred after such Issuance
because other Additional Common Shares were Issued or deemed Issued shall also
be recomputed.

          6.     RECOMPUTATION UPON EXPIRATION OF OPTIONS OR CONVERTIBLE
SECURITIES. The Exercise Price computed upon the original Issue of any Options
or Convertible Securities, and any subsequent adjustments based thereon, shall
be recomputed when any Options or rights of conversion under Convertible
Securities expire without having been exercised. In the case of Convertible
Securities or Options for Common Stock, the Exercise Price shall be recomputed
as if the only Additional Common Shares Issued were the shares of Common Stock
actually Issued upon the exercise of such securities, if any, and as if the only
consideration received therefor was the consideration actually received upon the
Issue, exercise or conversion of the Options or Convertible Securities. In the
case of Options for Convertible Securities, the Exercise Price shall be
recomputed as if the only Convertible Securities Issued were the Convertible
Securities actually Issued upon the exercise thereof, if any, and as if the only
consideration received therefor was the consideration actually received by the
Company (determined pursuant to Section 9), if any, upon the Issue of the
Options for the Convertible Securities.

          7.     LIMIT ON READJUSTMENTS. No readjustment of the Exercise Price
pursuant to Sections 5 or 6 shall increase the Exercise Price by more than the
amount of any decrease made in respect of the Issue of any Options or
Convertible Securities with respect to which such readjustment is made.

          8.     30 DAY OPTIONS. In the case of any Options that expire by their
terms not more than 30 days after the date of Issue thereof, no adjustment of
the Exercise Price shall be made until the exercise of such Options.

          9.     COMPUTATION OF CONSIDERATION. The consideration received by the
Company for the Issue of any Additional Common Shares shall be computed as
follows:

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                 (a)    CASH shall be valued at the amount of cash received by
the Company, excluding amounts paid or payable for accrued interest or accrued
dividends.

                 (b)    PROPERTY. Property other than cash shall be computed at
the fair market value thereof at the time of the Issue as determined in good
faith by the Board of Directors of the Company.

                 (c)    MIXED CONSIDERATION. The consideration for Additional
Common Shares Issued together with other property of the Company for
consideration that covers both shall be determined in good faith by the Board of
Directors.

                 (d)    OPTIONS AND CONVERTIBLE SECURITIES. The consideration
per Additional Common Share for Options and Convertible Securities shall be
determined by dividing:

                        (i)   the total amount, if any, received or receivable
by the Company for the Issue of the Options or Convertible Securities, plus the
minimum amount of additional consideration (as set forth in the instruments
relating thereto, without regard to any provision contained therein for a
subsequent adjustment of such consideration) payable to the Company upon
exercise of the Options or conversion of the Convertible Securities, by

                        (ii)  the maximum amount of Common Stock (as set forth
in the instruments relating thereto, without regard to any provision contained
therein for a subsequent adjustment of such number) ultimately issuable upon the
exercise of such Options or the conversion of such Convertible Securities.

          10.    GENERAL.

                 10.1   GOVERNING LAW. This Antidilution Agreement shall be
governed in all respects by the laws of the Commonwealth of Massachusetts as
such laws are applied to agreements between Massachusetts residents entered into
and to be performed entirely within Massachusetts.

                 10.2   SUCCESSORS AND ASSIGNS. Except as otherwise expressly
provided herein, the provisions hereof shall inure to the benefit of, and be
binding upon, the successors, assigns, heirs, executors and administrators of
the parties hereto.

                 10.3   ENTIRE AGREEMENT. This Antidilution Agreement and the
other documents delivered pursuant hereto or in connection herewith constitute
the full and entire understanding and agreement between the parties with regard
to the subjects hereof and thereof.

                 10.4   NOTICES, ETC. All notices and other communications
required or permitted hereunder shall be in writing and shall be mailed by first
class mail, postage prepaid, certified or registered mail, return receipt
requested, addressed (a) if to Purchaser at Purchaser's address(es) as set forth
below, or at such other address(es) as Purchaser shall have furnished to the
Company in writing, or (b) if to the Company, at the

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Company's address set forth below, or at such other address as the Company shall
have furnished to the Purchaser in writing.

                 10.5   SEVERABILITY. In case any provision of this Antidilution
Agreement shall be invalid, illegal, or unenforceable, the validity, legality
and enforceability of the remaining provisions of this Antidilution Agreement
shall not in any way be affected or impaired thereby.

                 10.6   TITLES AND SUBTITLES. The titles of the sections and
subsections of this Agreement are for convenience of reference only and are not
to be considered in construing this Antidilution Agreement.

                 10.7   COUNTERPARTS. This Antidilution Agreement may be
executed in any number of counterparts, each of which shall be an original, but
all of which together shall constitute one instrument.

PURCHASER                               COMPANY

SILICON VALLEY BANK                     CAMBRIDGE HEART, INC.


By: /s/ John V. Atanasoff               By:   /s/ Robert B. Palardy
   ----------------------                  -----------------------------
Name: John V. Atanasoff                 Name: Robert B. Palardy
Title: Regional Market Manager          Title: CFO
Address: One Newton Executive Park      Address: 1 Oak Park Dr.
         Newton, MA  02462                       Bedford, MA  01730

copy to: Silicon Valley Bank
         Treasury Department
         3003 Tasman Drive
         HA 200
         Santa Clara, CA 95054

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