Exhibit 99.6

CLINICAL AND MARKETING SUPPORT SERVICES AGREEMENT

CONFIDENTIAL

This Clinical and Marketing Support Services Agreement (this “ Agreement ”) is made and entered into as of this 11th day of December, 2007 (the “ Effective Date ”) among ABIOMED, Inc., a Delaware corporation (“ Abiomed ”), World Heart Corporation, an Ontario corporation (“ WHC ”) and World Heart Inc., a Delaware corporation (“ WHI ”).  Abiomed, WHC and WHI shall each, at times, be referenced herein individually as a “ Party ” and together as the “ Parties ”.

WITNESSETH:

WHEREAS, simultaneously with the execution and delivery of this Agreement, WHC, WHI and Abiomed are entering into a Note Purchase Agreement (the “ Purchase Agreement ”) through which Abiomed is purchasing an 8% secured convertible promissory note issued by WHC and WHI (the “ Note ”) and a warrant to purchase shares of the common stock of WHC (the “ Warrant ”); and

WHEREAS, in partial consideration for the Warrant, Abiomed wishes to make available and WHC wishes to have available, certain clinical and marketing support services to be provided by Abiomed to WHC and WHI;

NOW, THEREFORE, in consideration of the premises and other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the Parties hereby agree as follows:

1.             DEFINITIONS.

1.1.          Definitions . In addition to other terms specifically defined elsewhere in this Agreement, (a) capitalized terms that are not otherwise defined herein have the meanings given to such terms in the Purchase Agreement and (b) the following terms shall have the meanings indicated in this Section 1.1:

 “ Abiomed ” has the meaning set forth in the preamble.

“ Abiomed Default ” has the meaning set forth in Section 7.1(a).

 “ Abiomed Services ” means the Marketing Support Services and Clinical Support Services provided under this Agreement.

“ Affiliate ” means any Person who, directly or indirectly controls, is under common control with, or is controlled by, another Person, whether directly or indirectly through one or more intermediaries. For the purposes of this definition, “control” and its derivatives mean, with respect to any Person, the possession, directly or indirectly, of the

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power to direct or cause the direction of the management and policies of such Person, whether through the ownership of voting securities or otherwise.

“ Agreement ” has the meaning set forth in the preamble.

“ Assign ” and “ Assignment ” have the meanings set forth in Section 9.2.

“ Clinical Statement of Work ” has the meaning set forth in Section 3.2.

“ Clinical Support Services ” has the meaning set forth in Section  3.2 .

 “ Confidential Information ” shall mean all trade secrets and confidential or proprietary information owned, possessed or used by a Disclosing Party hereunder (whether in written, oral, graphical, machine-readable or other form) that is disclosed to a Receiving Party hereunder or to which the Receiving Party has access, including, without limitation, all such information concerning the Disclosing Party’s applications, concepts, developments, devices, designs, disclosures, discoveries, formulae, ideas, improvements, inventions, know-how, materials formulations, methods, processes, products, research results, specifications, systems, technical data, any and all clinical or non-clinical documentation, memoranda, notebooks, photos, sketches, prints, drawings, research materials, charts, graphs, machinery, prototypes, tools, written material and plans, as well as a Disclosing Party’s present or future business plans and strategies, financial models, cost estimates and analyses, operations, commercial activities, customers, suppliers and business partners, and all information of third parties that the Disclosing Party has an obligation to keep confidential.  To the extent reasonably practicable, the Disclosing Party will prominently mark “Confidential” on the cover page of all written materials to be provided to Receiving Party hereunder.

“ Disclosing Party ” shall mean the Party disclosing Confidential Information hereunder.

“ Governmental Authority ” has the meaning set forth in the Purchase Agreement.

“ Marketing Statement of Work ” has the meaning set forth in Section 3.3.

“ Marketing Support Services ” has the meaning set forth in Section 3.3.

 “ Note ” has the meaning set forth in the preamble.

“ Persons ” means any individual, corporation, partnership, company, joint venture, association, trust, unincorporated organization or Governmental Authority.

“ Receiving Party ” shall mean the Party receiving Confidential Information hereunder.

“ Term ” has the meaning set forth in Section 2.1.

 “ Warrant ” has the meaning set forth in the preamble.

“ WHC ” has the meaning set forth in the preamble hereof.

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“ WHI ” has the meaning set forth in the preamble hereof.

“ WHC Default ” has the meaning set forth in Section 7.2(a).

2.             TERM AND TERMINATION.

2.1.          Term . The term of this Agreement shall commence on the Effective Date hereof, and continue until the second anniversary thereof (the “ Term ”), unless terminated earlier pursuant to Section 7, or extended by mutual written agreement of all the Parties.

3.             DESCRIPTION OF ABIOMED SERVICES.

3.1.          Abiomed Services .  During the Term, Abiomed, WHC and WHI shall use good faith efforts to explore opportunities where they can work efficiently together for the mutual benefit of the Parties, including areas where Abiomed can provide the Abiomed Services described below in a cost-effective manner by leveraging economies of scale and existing infrastructure.

3.2.          Clinical Support Services . During the Term, WHC and WHI may, from time to time, request that Abiomed perform certain clinical support services for WHC or WHI (the “ Clinical Support Services ”); provided, however, that WHC and WHI are under no obligation to request any Clinical Support Services, or to request any minimum amount of Clinical Support Services during the Term.  If Abiomed agrees to perform such Clinical Support Services, the parties shall mutually agree on a written statement of work in the form of Exhibit B hereto (“ Clinical Statement of Work ”), provided, however, the Parties may mutually agree on variations to such form as required, on a case-by-case basis.  Examples of the types of Clinical Support Services that may be provided, upon mutual agreement, include the following:

Clinical Support (Clinical Field Specialist level):

(a)           On-site start-up and ongoing training of a clinical center’s clinical staff responsible for the care and management of LVAS recipients or LVAS hardware.

(b)           On-site clinical support to clinical centers, including but not limited to direct support at implants.  This would include from time-to-time, providing urgent clinical or technical on-site support.

(c)           Participation in a rotating schedule to provide 24-hour on-call clinical and technical support to clinical centers.

(d)           Documenting clinical experiences per WHC/WHI’s internal business and regulatory processes.

Clinical Trial Support (CRA I level):

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(e)           Conducting study site initiations and close-out visits in compliance with WHC/WHI Clinical Affairs operating procedures and policies.  Ensuring collection of required essential documents for study start-up and throughout conduct of study.

(f)            Conducting study site monitoring visits to ensure that conduct of a Clinical Trial is in compliance with the then-currently approved protocol/amendment(s), with GCP, and with applicable regulatory requirements.  Conducting source data/document verification.

3.3.          Marketing Support Services . During the Term, WHC and WHI may, from time to time, request that Abiomed perform certain marketing support services for WHC and WHI (the “ Marketing Support Services ”); provided, however, that WHC and WHI are under no obligation to request any Marketing Support Services, or to request any minimum amount of Marketing Support Services during the Term.  If Abiomed agrees to perform such Marketing Support Services, the parties shall mutually agree on a written statement of work in the form of Exhibit B hereto (“ Marketing Statement of Work ”), provided, however, the Parties may mutually agree on variations to such form as required, on a case-by-case basis.  Examples of the types of Marketing Support Services that may be provided, upon mutual agreement, include the following:

(a)           Strategic marketing and or consulting services related to WHC, WHI or their products; and

(b)           Abiomed providing WHC access to floor space and other resources purchased by Abiomed at trade-shows in which Abiomed, in its sole discretion, has agreed to participate, in order to provide WHC and WHI the opportunity to market and promote their products.

3.4.          Integration .  All executed Clinical Statements of Work and Marketing Statements of Work shall be attached as consecutively numbered exhibits to this Agreement, and each shall constitute an integral part of this Agreement.

4.             CONSIDERATION FOR ABIOMED SERVICES.

4.1.          Warrant .  In consideration for the Abiomed Services, WHC shall issue the Warrant to Abiomed on the Effective Date of this Agreement.

4.2.          Abiomed Fees .  In addition to the consideration provided in Section 4.1, WHI,  WHC and Abiomed shall agree in any Clinical Statement of Work or Marketing Statement of Work on additional reasonable compensation paid by WHC and WHI to Abiomed for any Abiomed Services, which compensation shall be at a negotiated price that is for the benefit of all of the Parties (“ Abiomed Fees ”).  The Parties agree to negotiate in good faith a level of Abiomed Fees that is mutually beneficial, with the intention of Abiomed providing the Abiomed Services in areas in which Abiomed can provide such services at cost savings to WHC or WHI.  Subject to any caps set forth on any Clinical Statement of Work or Marketing Statement of Work, the Abiomed Fees shall include, at a minimum, reimbursement for all incremental expenses directly and reasonably incurred by Abiomed in connection with the performance of the Abiomed

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Services, including, without limitation, travel and lodging expenses, and the costs of equipment and supplies necessary to provide the Abiomed Services (the “ Abiomed Expenses ”).  For the avoidance of doubt, the Abiomed Expenses shall include only those expenses that are not incurred in the ordinary course of Abiomed’s business, including without limitation fixed costs related to real estate and personnel.  WHC and WHI shall pay Abiomed the mutually agreed Abiomed Fees within thirty (30) calendar days following the receipt of a detailed statement of the Abiomed Fees, together with appropriate supporting documentation.

5.             WARRANTIES.

5.1.          Warranties Relating to Agreement Validity . In addition to any other representations and warranties contained in this Agreement, each Party represents and warrants to the other as of the Effective Date that:

(a)           it is duly organized and validly existing and in good standing in the jurisdiction of its organization;

(b)           it has the full right and authority to enter into, execute, deliver, and perform its obligations under this Agreement;

(c)           it has taken all requisite corporate or other action to approve the execution, delivery, and performance of this Agreement;

(d)           this Agreement constitutes its legal, valid and binding obligation enforceable against such Party in accordance with its terms;

(e)           to the best of its knowledge, there is no litigation, action, proceeding or investigation pending or threatened on any basis before any court or other Governmental Authority by, against, affecting or involving any of its business or assets that would affect its ability to carry out the transactions contemplated herein; and,

(f)            its execution of and performance under this Agreement does not violate any existing applicable law or any agreement to which it is a party.

5.2.          Requisite Standards . Abiomed represents and warrants that it has, or has access to, the requisite expertise and sufficient personnel and resources (including necessary supervision and support services) to deliver the Abiomed Services. Abiomed shall ensure that its employees have the requisite training to competently deliver the Abiomed Services.

5.3.          EXCLUSION OF WARRANTIES . EXCEPT AS SPECIFICALLY SET FORTH HEREIN, THE ABIOMED SERVICES PROVIDED BY ABIOMED TO WHC AND WHI PURSUANT TO THIS AGREEMENT SHALL BE “AS-IS.” NO OTHER WARRANTY TO WHC, WHI OR ANY OTHER PERSON, WHETHER EXPRESS, IMPLIED OR STATUTORY, IS MADE, WHETHER AS TO THE INSTALLATION, DESCRIPTION, QUALITY, MERCHANTABILITY, COMPLETENESS, USEFUL

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LIFE, FUTURE ECONOMIC VIABILITY, OR FITNESS FOR ANY PARTICULAR PURPOSE OF ANY ABIOMED SERVICE PROVIDED HEREUNDER OR DESCRIBED HEREIN, OR AS TO ANY OTHER MATTER, ALL OF WHICH ARE EXPRESSLY DISCLAIMED BY ABIOMED.

6.             FORCE MAJEURE

In the event that any Party shall be rendered wholly or partly unable to carry out its obligations under this Agreement, other than the obligation to pay money, by the occurrence of an event of force majeure, including fire, flood, earthquake, explosion, natural disaster, acts of God, riots, insurrection or other civil commotion, war, acts of terrorism, accidents, epidemics, reasonably unforeseen inability to obtain equipment or materials, reasonably unforeseen acts of government (other than acts of government directed exclusively at that Party, such as civil, criminal or regulatory action taken against the Party by name), then the performance of the obligations of the affected Party or Parties, other than the obligation to pay money, shall be excused for so long as such event of force majeure continues; provided, however, that the affected Party provides written notice to the other party of the occurrence of a force majeure event, makes reasonable efforts to remedy the disruption, and that, if such disruption due to force majeure continues for more than ninety (90) calendar days, then the party not affected by the force majeure event may terminate this Agreement by written notice which shall be effective upon receipt.

7.             DEFAULT.

7.1.          Abiomed Defaults and WHI and WHC Remedies.

(a)           Abiomed Defaults . The following events shall be defaults with respect to Abiomed (each, an “ Abiomed Default ”):

(i)            Abiomed (A) applies for or consents to the appointment of, or the taking of possession by, a receiver, custodian, trustee or liquidator of itself or of all or a substantial part of its property; (B) admits in writing its inability, or is generally unable, to pay its debts as such debts become due; (C) makes a general assignment for the benefit of its creditors; (D) commences a voluntary case under any bankruptcy law; (E) files a petition seeking to take advantage of any other law relating to bankruptcy, insolvency, reorganization, winding up, or composition or readjustment of debts; (F) fails to controvert in a timely and appropriate manner, or acquiesces in writing to, any petition filed against Abiomed in an involuntary case under any bankruptcy law; or (G) takes any corporate or other action for the purpose of effecting any of the foregoing;

(ii)           A proceeding or case is commenced without the application or consent of Abiomed in any court of competent jurisdiction seeking: (A) its liquidation, reorganization, dissolution or winding-up or the composition or readjustment of debts or (B) the appointment of a trustee, receiver, custodian, liquidator or the like of Abiomed under any bankruptcy law, and such proceeding or case shall continue undefended, or any

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