Exhibit 5.1


                        Opinion of McCarthy Tetrault LLP



                                                               December 23, 2003


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


Dear Sirs,

              Re: Registration Statement of World Heart Corporation

We have acted as Canadian counsel to World Heart Corporation, a corporation
incorporated under the laws of the Province of Ontario, Canada (the "Company")
in connection with the offer for resale in the United States of 11,909,231
post-consolidated common shares of the Company pursuant to a Registration
Statement on Form F-3 (the "Registration Statement") filed with the Securities
and Exchange Commission pursuant to the Securities Act of 1933, as amended (the
"Securities Act").

We have examined such corporate records, agreements and other instruments and
documents as we have deemed necessary as a basis for the opinion hereinafter
expressed. As to questions of fact, material to such opinions, we have, when
relevant facts were not independently established by us, relied on the documents
we have examined or upon the certifications and representations of officers of
the Company. We have assumed the authenticity of all the documents presented to
us as originals.

Based on the foregoing and having regard to the legal considerations which we
deemed relevant, we are of the opinion that:

     (i)  the 4,624,821 post-consolidated common shares of the Company which
          have been issued pursuant to subscription agreements dated September
          22 2003 between certain purchasers of units in Canada (the
          "Subscription Agreements") and the Company, each unit consisting of
          one common share of the Company and one warrant exercisable for one
          common share of the Company (the "Warrants"), and an agency agreement
          dated September 22, 2003 between the Company and Research Capital
          Corporation (the "Canadian Agent"), have been duly and validly issued
          as

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          fully paid and non-assessable common shares in the capital of the
          Company;

     (ii) the 4,624,821 post-consolidated common shares of the Company issuable
          upon the exercise of the Warrants, which Warrants have been issued
          pursuant to the Subscription Agreements and the Agency Agreement, have
          been duly and validly allotted and reserved for issuance and, when
          issued upon the due exercise of the Warrants in accordance with the
          terms of the warrant certificates and the warrant indenture dated
          September 22, 2003 between the Company and CIBC Mellon Trust Company,
          as warrant agent, and upon payment to the Company of the exercise
          price therefor, will be duly and validly issued as fully paid and
          non-assessable common shares in the capital of the Company;

    (iii) the 448,000 post-consolidated common shares of the Company issuable
          upon the exercise of the warrants issued to the Canadian Agent (the
          "Agent's Warrants") pursuant to the Agency Agreement, have been duly
          and validly allotted and reserved for issuance and, when issued upon
          the due exercise of the Agent's Warrants in accordance with the terms
          of the Agent's Warrants certificate and upon payment to the Company of
          the exercise price therefor, will be duly and validly issued as fully
          paid and non-assessable common shares in the capital of the Company;

     (iv) upon the conversion of 4,981,128 Series A Cumulative Participating
          Preferred shares of World Heart Inc., a subsidiary of the Company,
          held by Edwards Lifesciences LLC, 711,589 post-consolidated common
          shares of the Company have been duly and validly issued as fully paid
          and non-assessable common shares in the capital of the Company; and

     (v)  upon the conversion of 1,374,570 Series A Cumulative Redeemable
          Convertible Preferred Shares of the Company held by Edwards
          Lifesciences (U.S.) Inc., 500,000 post-consolidated common shares of
          the Company have been validly issued as fully paid and non-assessable
          shares of the Company and 1,000,000 post-consolidated common shares of
          the Company issuable upon the exercise of warrants, each warrant
          exercisable for one post-consolidated common share, have been duly and
          validly allotted and reserved for issuance and, when issued upon the
          due exercise of the warrants in accordance with the terms of the
          warrant certificate, and upon payment to the Company of the exercise
          price therefor, will be duly and validly issued as fully paid and
          non-assessable common shares in the capital of the Company.


We do not express any opinion as to any laws other than the laws of the Province
of Ontario and the laws of Canada applicable therein.

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We consent to the filing of this opinion as an exhibit to the Registration
Statement and the reference to the name of our firm therein, without thereby
admitting that we are "experts" under the Securities Act or the rules and
regulations of the Securities and Exchange Commission thereunder for the
purposes of any part of the Registration Statement.


                                               Yours very truly,

                                               /s/ McCarthy Tetrault LLP

                                               McCarthy Tetrault LLP