EXHIBIT 99.2

                                                                 EXECUTION COPY


                        COMMON STOCK PURCHASE AGREEMENT

                                    between

                                 ABIOMED, Inc.

                                      and

                              GENZYME CORPORATION

                           dated as of July 14, 1997

 
                               TABLE OF CONTENTS


                                                                                                         
ARTICLE 1. PURCHASE AND SALE OF SHARES...................................................................... 1

1.1. Authorization.......................................................................................... 1
1.2. Sale and Purchase of the Shares........................................................................ 1
1.3. Delivery of Certificates............................................................................... 1

ARTICLE 2.  REPRESENTATIONS AND WARRANTIES OF ABIOMED....................................................... 1

2.1. Organization and Qualification......................................................................... 1
2.2. Capitalization......................................................................................... 2
2.3. Issuance and Sale of Shares............................................................................ 3
2.4. Authority for Agreement................................................................................ 3
2.5. SEC Reports............................................................................................ 3
2.6. Financial Statements................................................................................... 3
2.7. Subsidiaries........................................................................................... 4
2.8. Absence of Undisclosed ABIOMED Liabilities............................................................. 4
2.9. No Material Adverse Change............................................................................. 4
2.10. Tax Matters........................................................................................... 5
2.11. No Breach............................................................................................. 5
2.12. Actions and Proceedings............................................................................... 6
2.13. Compliance with Laws.................................................................................. 6
2.14. Brokerage............................................................................................. 6
2.15. Full Disclosure....................................................................................... 6

ARTICLE 3.  REPRESENTATIONS AND WARRANTIES OF GENZYME....................................................... 6

3.1. Authority for Agreement................................................................................ 7
3.2. Investment............................................................................................. 7
3.3. Restrictions on Transferability; Legend................................................................ 7
3.4. Information............................................................................................ 7
3.5. Brokerage.............................................................................................. 8

ARTICLE 4.  CONDITIONS PRECEDENT............................................................................ 8

ARTICLE 4.  COVENANTS OF ABIOMED............................................................................ 8

5.1. Corporate Existence.................................................................................... 8
5.2. Reporting Status....................................................................................... 9
5.3. Listing................................................................................................ 9
5.4. Use of Proceeds........................................................................................ 9
5.5. Information to be Furnished............................................................................ 9

ARTICLE 6.  COVENANTS OF GENZYME............................................................................ 9

6.1. Standstill Agreement................................................................................... 9
6.2. Voting of Shares.......................................................................................11
6.3. Henri A. Termeer.......................................................................................11
6.4. Release of Restrictions................................................................................11


 

                                                                                                         
ARTICLE 7.  REGISTRATION RIGHTS.............................................................................11

7.1. Certain Definitions....................................................................................11
7.2. Required Registration..................................................................................12
7.3. Incidental Registration................................................................................13
7.4. Conditions of Obligations to Register Shares...........................................................14
7.5. Registration Procedures................................................................................14
7.6. Description of Expenses................................................................................17
7.7. Indemnification........................................................................................17

ARTICLE 8.  CONFIDENTIALITY.................................................................................19

8.1. Non-Disclosure Obligations.............................................................................19
8.2. Exceptions to Non-Disclosure Obligations...............................................................20
8.3. Ownership of Confidential Information..................................................................20
8.4. Destruction of Confidential Information................................................................20
8.5. Material Inside Information............................................................................21
8.6. Terms of this Agreement................................................................................21

ARTICLE 9.  JOINT DEVELOPMENT AND COLLABORATIONS............................................................21

10.1. Assignment............................................................................................21
10.2. Severability..........................................................................................21
10.3. Notices...............................................................................................22
10.4. Applicable Law........................................................................................22
10.5. Entire Agreement......................................................................................22
10.6. Headings..............................................................................................23
10.7. Counterparts..........................................................................................23


 
                        COMMON STOCK PURCHASE AGREEMENT


     THIS COMMON STOCK PURCHASE AGREEMENT dated as of July 14, 1997 (the
"Agreement") is between ABIOMED, Inc., a Delaware corporation having its
- ----------                                                              
principal place of business at 33 Cherry Hill Drive, Danvers, Massachusetts
01923 ("ABIOMED"), and Genzyme Corporation, a Massachusetts corporation having
        -------                                                               
its principal place of business at One Kendall Square, Cambridge, Massachusetts
02139 ("Genzyme").  ABIOMED and Genzyme are sometimes referred to herein
        -------                                                         
individually as a "Party" and collectively as the "Parties."
                   -----                           -------  


     In consideration of the mutual promises and of the covenants contained
herein, the Parties hereby agree as follows:

                   ARTICLE 1.   PURCHASE AND SALE OF SHARES

     1.1.  Authorization.
           ------------- 

     ABIOMED has duly authorized the issuance and sale to Genzyme of 1,153,846
shares (the "Shares") of its Common Stock, $0.01 par value per share ("Common
                                                                       ------   
Stock").
- ------   

     1.2.  Sale and Purchase of the Shares.
           ------------------------------- 

     Concurrently with the execution and delivery of this Agreement, ABIOMED
hereby issues and sells to Genzyme, and Genzyme hereby purchases from ABIOMED,
the Shares at a purchase price of $13.00 per Share, for an aggregate purchase
price of Fourteen Million Nine Hundred Ninety-Nine Thousand Nine Hundred Ninety-
Eight Dollars ($14,999,998), payable by Genzyme to ABIOMED upon execution of
this Agreement.

     1.3.  Delivery of Certificates.
           ------------------------ 

     On the date hereof, ABIOMED will deliver to Genzyme one or more
certificates representing the Shares registered in the name of Genzyme against
payment by Genzyme of the purchase price by check or wire transfer.

             ARTICLE 2.  REPRESENTATIONS AND WARRANTIES OF ABIOMED

     Except as otherwise set forth in the disclosure schedule delivered to
Genzyme on the date hereof (the "Disclosure Schedule"), the section numbers of
                                 -------------------                          
which are numbered to correspond to the sections of this Agreement to which they
refer, ABIOMED represents and warrants to Genzyme as follows:

     2.1.  Organization and Qualification.
           ------------------------------ 

                                       1

 
     Each of ABIOMED and the Subsidiaries (as defined in Section 2.7) is a
corporation or partnership duly organized, validly existing and in good standing
under the laws of its state or jurisdiction of incorporation or formation with
full power and authority to own, lease and operate its assets, properties and
business and to carry on its business as now being and as heretofore conducted.
Each of ABIOMED and the Subsidiaries is qualified or otherwise authorized to
transact business as a foreign corporation or partnership in all jurisdictions
in which such qualification or authorization is required by law, except for
jurisdictions in which the failure to so qualify or be authorized would not have
a material adverse effect on the assets, properties, business, operations or
condition (financial or otherwise) of ABIOMED and the Subsidiaries taken as a
whole (the "Business of ABIOMED").
            -------------------   

     2.2.  Capitalization.
           -------------- 

           (a) ABIOMED is authorized to issue 25,000,000 shares of Common Stock,
               of which 7,017,872 shares were issued and outstanding as of June
               30, 1997, 2,346,000 shares of Class A Common Stock, $0.01 par
               value per share, none of which are issued and outstanding,
               150,000 shares of Class A Preferred Stock, $0.01 par value per
               share, none of which are issued and outstanding, and 1,000,000
               shares of Class B Preferred Stock, $0.01 par value per share,
               none of which are issued and outstanding. No other class of
               capital stock of ABIOMED is authorized or outstanding. All of the
               issued and outstanding shares of ABIOMED's capital stock are duly
               authorized and are validly issued, fully paid, nonassessable and
               free of preemptive rights. None of the issued and outstanding
               shares have been issued in violation of any federal or state law
               except for violations that would not have a material adverse
               effect on the Business of ABIOMED.

           (b) Options representing in the aggregate the right to purchase
               919,785 shares of Common Stock pursuant to ABIOMED's 1992
               Combination Stock Option Plan and ABIOMED's 1989 Non-Qualified
               Stock Option Plan for Non-Employee Directors are outstanding as
               of the date hereof.

           (c) 90,718 shares of Common Stock are reserved for issuance under
               ABIOMED's 1988 Employee Stock Purchase Plan as of the date
               hereof.

           (d) Except as set forth in paragraphs (a), (b) and (c) of this
               Section 2.2, Section 2.2 of the Disclosure Schedule or as a
               result of the exercise of outstanding options or rights set forth
               therein, there are not, as of the date hereof, any other shares
               of ABIOMED capital stock authorized or outstanding or any
               subscriptions, options, conversion or exchange rights, warrants,
               repurchase or redemption agreements, or other agreements or
               commitments obligating ABIOMED to issue, transfer, sell,
               repurchase or redeem any shares of its capital stock or other
               securities of ABIOMED. To the best knowledge of ABIOMED, there
               are no written stockholder agreements, voting trusts, proxies or
               other agreements, instruments or

                                       2

 
               understandings with respect to the voting of the capital stock of
               ABIOMED.

     2.3.  Issuance and Sale of Shares.
           --------------------------- 

     The issuance and sale of the Shares by ABIOMED has been duly authorized and
the Shares have been duly reserved for issuance by all necessary corporate
action on the part of ABIOMED, and the Shares, when issued and delivered against
payment therefor, will be duly and validly issued, fully paid and non-
assessable. Based in part on the representations made by Genzyme set forth in
Article 3 below, the offer, issuance and sale of the Shares pursuant to this
Agreement are exempt from registration under the Securities Act of 1933, as
amended (the "Securities Act"), and applicable state securities laws. ABIOMED
              --------------                                                  
has complied with all applicable federal and state securities laws and with the
Nasdaq By-Laws in connection with the offer, issuance and sale of the Shares.

     2.4.  Authority for Agreement.
           ----------------------- 

     The execution, delivery and performance by ABIOMED of this Agreement has
been duly authorized by all necessary corporate action, and this Agreement has
been duly executed and delivered by ABIOMED. This Agreement constitutes the
valid and binding obligation of ABIOMED enforceable against ABIOMED in
accordance with its terms, subject to applicable bankruptcy, insolvency,
moratorium and similar laws affecting the rights and remedies of creditors
generally and to general principles of equity.

     2.5.  SEC Reports.
           ----------- 

     ABIOMED has previously delivered to Genzyme its (a) Annual Report on
Form 10-K for the year ended March 31, 1997 (the "ABIOMED 10-K"), as filed with
                                                  ------------                 
the Securities and Exchange Commission (the "SEC"), (b) all proxy statements
                                             ---                            
relating to ABIOMED's meetings of stockholders held or currently scheduled to be
held since March 31, 1997 and (c) all other reports filed by ABIOMED with the
SEC under the Securities Exchange Act of 1934, as amended (the "Exchange Act"),
                                                                ------------   
since March 31, 1997.  As of their respective dates, such reports complied in
all material respects with applicable SEC requirements and did not contain any
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, in light of the
circumstances under which they were made, not misleading.  ABIOMED has timely
filed with the SEC all reports required to be filed under Section 13, 14 or
15(d) of the Exchange Act since March 31, 1997.

     2.6.  Financial Statements.
           -------------------- 

     The financial statements contained in the ABIOMED 10- K have been prepared
from, and are in accordance with, the books and records of ABIOMED and present
fairly, in all material respects, the financial condition and results of
operations of ABIOMED as of and for the periods presented therein, all in
conformity with United States generally accepted accounting principles,
consistently applied, except as otherwise noted therein.

                                       3

 
     2.7.  Subsidiaries.
           ------------ 

           (a) The Disclosure Schedule sets forth all of the Subsidiaries and
               the jurisdiction in which each is incorporated or organized.
               Except as set forth on the Disclosure Schedule, all issued and
               outstanding shares or partnership interests of each Subsidiary
               are owned directly by ABIOMED free and clear of any charges,
               liens, encumbrances, security interests or adverse claims. As
               used in this Agreement, "Subsidiary" means any corporation,
               partnership or other legal entity of which ABIOMED or any
               Subsidiary owns, directly or indirectly, 50% or more of the stock
               or other equity interest entitled to vote for the election of
               directors.

           (b) Except as set forth on the Disclosure Schedule, there are not as
               of the date hereof any other shares of capital stock or other
               equity interest of any Subsidiary authorized or outstanding or
               any subscriptions, options, conversion or exchange rights,
               warrants, repurchase or redemption agreements, or other
               agreements, claims or commitments of any nature whatsoever
               obligating any Subsidiary to issue, transfer, deliver, sell,
               repurchase or redeem any shares of the capital stock or other
               equity interest of any Subsidiary or obligating ABIOMED or any
               Subsidiary to grant, extend or enter into any such agreement. To
               the best knowledge of ABIOMED, there are no stockholder
               agreements, voting trusts, proxies or other agreements,
               instruments or understandings with respect to the capital stock
               of any Subsidiary.

           (c) Except for the Subsidiaries, ABIOMED does not directly or
               indirectly own or have any investment in any of the capital stock
               of, and is not a party to a partnership or joint venture with,
               any other person.

     2.8.  Absence of Undisclosed ABIOMED Liabilities.
           ------------------------------------------ 

     As of March 31, 1997, ABIOMED and the Subsidiaries had no material
liabilities of any nature, whether accrued, absolute, contingent or otherwise,
(a) required to be reflected or disclosed on the balance sheets dated March 31,
1997 (or the notes thereto) included in the ABIOMED 10-K that were not
adequately reflected or reserved against on such balance sheets or (b) for the
payment of any dividends, or any other distribution, to the stockholders of
ABIOMED. ABIOMED and the Subsidiaries have no such liabilities, other than
liabilities (i) adequately reflected or reserved against on such balance sheet,
(ii) incurred since March 31, 1997 in the ordinary course of business and
consistent with past practice or (iii) that would not, in the aggregate, have a
material adverse effect on the Business of ABIOMED.

     2.9.  No Material Adverse Change.
           -------------------------- 
           
     Since March 31, 1997, there has not been any material adverse change in the
Business of ABIOMED.

                                       4

 
     2.10. Tax Matters.
           ----------- 

           (a) ABIOMED and each of the Subsidiaries have filed all tax reports
               and returns required to be filed by them and have paid or will
               timely pay all taxes and other charges shown as due on such
               reports and returns. Neither ABIOMED nor any of the Subsidiaries
               is delinquent in the payment of any material tax assessment or
               other governmental charge (including without limitation
               applicable withholding taxes). Any provision for taxes reflected
               in the financial statements referenced in Section 2.6 above is,
               to the best knowledge of ABIOMED, adequate for payment of any and
               all tax liabilities for periods ending on or before March 31,
               1997 and there are no tax liens on any assets of ABIOMED or the
               Subsidiaries except liens for current taxes not yet due.

           (b) Except as set forth in the Disclosure Schedule, there has not
               been any audit of any tax return filed by ABIOMED or any of the
               Subsidiaries and no audit of any such tax return is in progress
               and neither ABIOMED nor any Subsidiary has been notified by any
               tax authority that any such audit is contemplated or pending.
               ABIOMED knows of no material tax deficiency or claim for
               additional taxes asserted or threatened to be asserted against
               ABIOMED or any of the Subsidiaries by any taxing authority and
               ABIOMED knows of no grounds for any such assessment. No extension
               of time with respect to any date on which a tax return was or is
               to be filed by ABIOMED or any of the Subsidiaries is in force,
               and no waiver or agreement by ABIOMED or any of the Subsidiaries
               is in force for the extension of time for the assessment or
               payment of any tax. For purposes of this Agreement, the term
               "tax" includes all federal, state, local and foreign taxes or
               assessments, including income, sales, gross receipts, excise,
               use, value added, royalty, franchise, payroll, withholding,
               property and import taxes and any interest or penalties
               applicable thereto.

     2.11. No Breach.
           --------- 

     The execution, delivery and performance of this Agreement and the
consummation of the transactions contemplated hereby will not: (a) violate any
provision of the certificate of incorporation or by-laws of ABIOMED; (b)
violate, conflict with or result in the breach of any of the terms or conditions
of, result in modification of the effect of, or otherwise give any other
contracting party the right to terminate, or constitute (or with notice or lapse
of time or both constitute) a default under, any material instrument, contract
or other agreement to which ABIOMED or any of the Subsidiaries is a party or to
which any of the assets or properties of ABIOMED or any of the Subsidiaries may
be bound or subject; (c) violate any order, judgment, injunction, award or
decree of any court, arbitrator or governmental or regulatory body against, or
binding upon, ABIOMED, any Subsidiary or upon any of their respective
securities, properties, assets or businesses; (d) violate any statute, law or
regulation of any jurisdiction as such statute, law or regulation relates to
ABIOMED, any Subsidiary or any of their respective

                                       5

 
securities, properties, assets or businesses; (e) require the approval, consent
or authorization of, or registration or filing with, any foreign, federal,
state, local or other governmental or regulatory body or the approval, consent,
waiver or notification of any stockholder, creditor, lessor or other person; or
(f) result in the creation of any lien or other encumbrance on the assets or
properties of ABIOMED or any of the Subsidiaries, excluding from clauses (b) -
(f) such matters as would not in the aggregate have a material adverse effect on
the Business of ABIOMED or upon the transactions contemplated hereby.

     2.12. Actions and Proceedings.
           ----------------------- 

     There are no outstanding orders, judgments, injunctions, awards or decrees
of any court, governmental or regulatory body or arbitration tribunal against
ABIOMED, any Subsidiary or any of their respective properties or assets. There
are no actions, suits or claims or legal, administrative or arbitral proceedings
or, to the best knowledge of ABIOMED, investigations (whether or not the defense
thereof or liabilities in respect thereof are covered by insurance) pending or,
to the best knowledge of ABIOMED, threatened against ABIOMED, any Subsidiary or
any of their respective properties or assets.

     2.13. Compliance with Laws.
           -------------------- 

     To its knowledge, neither ABIOMED nor any of the Subsidiaries is in
violation of any statute, law, rule or regulation, or in default with respect to
any judgment, writ, injunction, decree, rule or regulation of any court,
governmental or regulatory body or arbitration tribunal, including without
limitation laws relating to environmental protection, health and safety matters
and labor and employment practices, except for such violations or defaults which
do not, individually or in the aggregate, materially and adversely affect the
Business of ABIOMED.

     2.14. Brokerage.
           --------- 

     Except as set forth in the Disclosure Schedule, no broker, finder, agent or
similar intermediary has acted on behalf of ABIOMED in connection with this
Agreement or the transactions contemplated hereby, and there are no brokerage
commissions, finders fees or similar fees or commissions payable in connection
therewith based on any agreement, arrangement or understanding with ABIOMED or
any action taken by ABIOMED.

     2.15. Full Disclosure.
           --------------- 

     The representations and warranties of ABIOMED contained in this Agreement,
together with the ABIOMED 10-K, taken as a whole as of the date hereof, do not
(a) contain an untrue statement of a material fact or omit to state a material
fact required to be stated or necessary to make the statements made, in light of
the circumstances under which made, not false or misleading or (b) omit to state
a material fact known to ABIOMED that reasonably could be expected to materially
adversely affect the Business of ABIOMED.

             ARTICLE 3.  REPRESENTATIONS AND WARRANTIES OF GENZYME

                                       6

 
     Genzyme hereby represents and warrants to ABIOMED as follows:

     3.1.  Authority for Agreement.
           ----------------------- 

     The execution, delivery and performance by Genzyme of this Agreement has
been duly authorized by all necessary corporate action, and this Agreement has
been duly executed and delivered by Genzyme. This Agreement constitutes the
valid and binding obligation of Genzyme enforceable against Genzyme in
accordance with its terms, subject to applicable bankruptcy, insolvency,
moratorium and similar laws affecting the rights and remedies of creditors
generally and to general principles of equity.

     3.2.  Investment.
           ---------- 

     Genzyme is an accredited investor, as defined in Rule 501 of Regulation D
under the Securities Act. Genzyme is acquiring the Shares solely for its own
account for investment purposes as a principal and not with a view to the public
resale or distribution of all or any part thereof; provided, however, that in
making such representation, Genzyme does not agree to hold the Shares for any
minimum or specific term and reserves the right to sell, transfer or otherwise
dispose of the Shares at any time in accordance with the terms of this Agreement
and with federal and state securities laws applicable to such sale, transfer or
disposition.

     3.3.  Restrictions on Transferability; Legend.
           --------------------------------------- 

     Genzyme understands that the Shares have not been registered under the
Securities Act or under the securities laws of any state or other jurisdiction
in reliance upon exemptions thereunder.  Genzyme acknowledges and is aware that
the Shares cannot be resold unless the Shares are registered under the
Securities Act and any applicable securities law of any state or other
jurisdiction, or an exemption from registration is available.  Each certificate
representing the Shares shall bear a legend in substantially the following form
(unless such Shares have been transferred pursuant to a registration statement
under the Securities Act or, in the opinion of counsel acceptable to ABIOMED,
such a legend is not required):

           THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED
           UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE "ACT"), OR ANY
           STATE SECURITIES LAW AND MAY NOT BE TRANSFERRED EXCEPT (i) PURSUANT
           TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE ACT OR (ii) UPON
           FIRST FURNISHING TO THE COMPANY AN OPINION OF COUNSEL SATISFACTORY TO
           IT THAT SUCH TRANSFER IS NOT IN VIOLATION OF THE REGISTRATION
           REQUIREMENTS OF THE ACT OR ANY STATE SECURITIES LAW.

     3.4.  Information.
           ----------- 

     Genzyme has reviewed (a) the representations of ABIOMED contained in this
Agreement and (b) the ABIOMED 10-K and has had the opportunity to make inquiry
concerning 

                                       7

 
ABIOMED and its business and personnel. The officers of ABIOMED have made
available to Genzyme any and all written information that it has requested and
have answered to Genzyme's satisfaction all inquiries made by Genzyme. Genzyme
acknowledges that Henri A. Termeer, President and Chief Executive Officer of
Genzyme, is a member of the Board of Directors of ABIOMED, and in that capacity
Mr. Termeer has knowledge of the Business of ABIOMED.

     3.5.  Brokerage.
           --------- 

     No broker, finder, agent or similar intermediary has acted on behalf of
Genzyme in connection with this Agreement or the transactions contemplated
hereby, and there are no brokerage commissions, finders fees or similar fees or
commissions payable in connection therewith based on any agreement, arrangement
or understanding with Genzyme, or any action taken by it.

                        ARTICLE 4.  CONDITIONS PRECEDENT

     Contemporaneously with the execution of this Agreement, ABIOMED shall
deliver to Genzyme:

           (a) The certificate of incorporation, as amended, of ABIOMED,
               certified by the Secretary of State of Delaware as of the most
               recent practicable date;

           (b) Certificates, as of the most recent practicable date, as to the
               corporate good standing and legal existence of ABIOMED issued by
               the Secretary of State of Delaware and the Secretary of the
               Commonwealth of Massachusetts, each confirming such good standing
               and legal existence as of such date;

           (c) By-laws of ABIOMED, certified by its Secretary as of the date
               hereof;

           (d) Resolutions of the Board of Directors of ABIOMED authorizing and
               approving this Agreement and the issuance of the Shares hereby,
               certified by the Secretary of ABIOMED as of the date hereof; and

           (e) An opinion of counsel to ABIOMED, dated as of the date hereof and
               addressed to Genzyme, in a form reasonably acceptable to Genzyme
               and its counsel.

                       ARTICLE 5.  COVENANTS OF ABIOMED

     5.1.  Corporate Existence.
           ------------------- 

     ABIOMED will do or cause to be done all things necessary to preserve and
keep in full force and effect its corporate existence; provided, however,
nothing herein shall prevent or limit the right of ABIOMED to merge or
consolidate with any other entity or to sell all or substantially

                                       8

 
all of its assets to another entity followed by a dissolution of ABIOMED, or to
enter into any similar transaction.

     5.2.  Reporting Status.
           ---------------- 

     For so long as Genzyme or any affiliate of Genzyme beneficially owns any of
the Shares, ABIOMED (a) shall timely file with the SEC any and all reports
required to be so filed pursuant to the Exchange Act and (b) shall not terminate
its status as an issuer required by the Exchange Act to file reports thereunder
even if the Exchange Act or the rules or regulations thereunder would permit
such termination.

     5.3.  Listing.
           ------- 

     For so long as Genzyme or any affiliate of Genzyme beneficially owns any of
the Shares, ABIOMED shall cause the Common Stock to continue to be listed for
trading on Nasdaq or on a national securities exchange.

     5.4.  Use of Proceeds.
           --------------- 

     ABIOMED will use amounts paid for the Shares hereunder for working capital
and general corporate purposes, including research and development of new
products and product enhancements, including the development of a battery-
powered implantable total artificial heart, subject to adjustment based upon the
results of development efforts, delays or changes in governmentally required
testing and approval procedures, changing market conditions and other risks
described in the ABIOMED 10-K.

     5.5.  Information to be Furnished.
           --------------------------- 

     For so long as Genzyme or any affiliate of Genzyme holds Shares
representing at least 1% of the outstanding shares of Common Stock, ABIOMED will
furnish promptly to Genzyme copies of (a) each report and proxy statement filed
by ABIOMED with the SEC pursuant to Section 13(a), 14 or 15(d) of the Exchange
Act, (b) all financial statements, periodic and special reports and investor
relations materials as ABIOMED may distribute to all holders of Common Stock
generally and (c) all press releases issued by ABIOMED.

                       ARTICLE 6.  COVENANTS OF GENZYME

     6.1.  Standstill Agreement.
           -------------------- 

     Genzyme agrees that, unless it has obtained the prior written consent of
ABIOMED or the restrictions contained in this Article 6 have otherwise been
released or suspended as provided below, it will not, nor will it allow its
Affiliates (as that term is defined in Rule 12b-2 under the Exchange Act,
regardless of whether such person is an Affiliate on the date hereof) to:

           (a) acquire, offer to acquire or enter into any agreement to acquire,
               directly or indirectly, by purchase or otherwise, record or
               beneficial ownership of any 

                                       9

 
               additional voting securities of ABIOMED or direct or indirect
               rights or options to acquire (through purchase, exchange,
               conversion or otherwise) voting securities of ABIOMED;

           (b) "solicit" proxies with respect to voting securities under any
               circumstances, in any way participate in any "solicitation" of
               "proxies" or become a "participant" in any "election contest"
               relating to the election of directors of ABIOMED, as such terms
               are defined in Regulation 14A under the Exchange Act;

           (c) deposit any voting securities in a voting trust or subject them
               to a voting agreement or other agreement of similar effect;

           (d) call any special meeting of stockholders of ABIOMED or initiate
               or participate in the initiation of any special meeting of
               stockholders of ABIOMED for any purpose;

           (e) initiate, propose or otherwise solicit stockholders for the
               approval of one or more stockholder proposals at any time, or
               induce or attempt to induce any other person to initiate any
               stockholder proposal;

           (f) request, or take any action to obtain or retain from ABIOMED,
               directly or indirectly, any list of holders of securities (other
               than to avail itself of the inspection rights set forth in
               Sections 219 and 220 of the Delaware General Corporation Law, or
               any similar successor statutory provisions, for any proper
               purpose);

           (g) fail to withdraw any proposal relating to any matter set forth in
               this Section 6.1 that, in the written opinion of counsel to
               ABIOMED, would require ABIOMED to make a public announcement with
               respect thereto;

           (h) form, join or in any way participate in a "group" (within the
               meaning of Section 13(d)(3) of the Exchange Act) with respect to
               any voting securities of ABIOMED;

           (i) assist, advise, encourage or influence in any respect any third
               party to seek to control management of ABIOMED including, without
               limitation (i) proposing any business combination or similar
               transaction with, a change in control of, or any restructuring,
               recapitalization or other extraordinary transaction involving,
               ABIOMED, (ii) influencing the management, board of directors or
               policies of ABIOMED or (iii) acquiring, holding, voting or
               disposing of voting securities of ABIOMED; or

           (j) take any action individually or jointly with any partnership,
               limited partnership, syndicate, or other group or assist any
               other person,

                                       10

 
               corporation, entity or group in taking any action it could not
               take individually under the terms of this Agreement.

     6.2.  Voting of Shares.
           ---------------- 

     For so long as the restrictions contained in Section 6.1 remain in effect,
Genzyme shall take such action as may be required so that (a) all voting
securities held by it or any of its Affiliates shall be present for purposes of
determining a quorum at every meeting of the holders of Common Stock and (b)
such securities shall be voted in the same proportion as the votes cast by
holders of the same class of voting securities other than Genzyme and its
Affiliates, or, in Genzyme's discretion, in accordance with the recommendations
of ABIOMED's Board of Directors.

     6.3.  Henri A. Termeer.
           ---------------- 

     The restrictions of this Article 6 shall not prohibit (i) the grant to
Henri A. Termeer, in connection with his position as a member of the Board of
Directors of ABIOMED, of shares of Common Stock or options to acquire shares of
Common Stock, or the exercise by Mr. Termeer of any such options or (ii) the
exercise by Mr. Termeer of his fiduciary duties as a member of the Board of
Directors of ABIOMED.

     6.4.  Release of Restrictions.
           ----------------------- 

     Notwithstanding the foregoing, the restrictions contained in this Article
6:

           (a) shall be suspended during such time as the Board of Directors of
               ABIOMED determines to accept bids from any responsible bidder to
               obtain the best price for the sale of ABIOMED, but only so long
               as ABIOMED continues to accept such bids or negotiate or
               consummate a transaction with any bidder;

           (b) shall be suspended during such time as any third party makes an
               unsolicited offer to acquire more than fifty percent (50%) of the
               outstanding voting securities of ABIOMED, but only so long as
               such offer is outstanding; and

           (c) shall be released after the fifth anniversary of the date hereof.

                        ARTICLE 7.  REGISTRATION RIGHTS

     7.1.  Certain Definitions.
           ------------------- 
     As used in this Article 7, the following terms shall have the following
respective meanings:

                                       11

 
           (a) "Holders" shall mean Genzyme and any of its successors and
               assigns (other than successors and assigns who acquire the Shares
               pursuant to a registered public offering or pursuant to a
               transaction covered by Rule 144 under the Securities Act) who
               hold at least 5% of the Common Stock.

           (b) "Registration Expenses" and "Selling Expenses" shall mean the
               expenses so described in Section 7.6. "Other Holders" shall mean
               all holders of the Company's securities other than Holders.

           (d) "Underwriter" shall mean each person who is or may be deemed an
               "underwriter," as that term is defined in Section 2(11) of the
               Securities Act, in respect of securities which shall have been
               registered by ABIOMED under the Securities Act pursuant to any of
               the provisions of this Article 7.

     7.2.  Required Registration.
           --------------------- 

           (a) At any time after the first anniversary of the date hereof and
               prior to the seventh anniversary of the date hereof, the
               Holder(s) of at least 25% of the then unregistered Shares may
               notify ABIOMED in writing that such Holder(s) intend to offer or
               cause to be offered for sale unregistered Shares and request
               ABIOMED to cause such Shares to be registered under the
               Securities Act if such registration may be effected on Form S-3
               (or any similar or successor form promulgated by the SEC). Such
               right to require registration shall be available to Holders on
               not more than a total of three (3) occasions, and on not more
               than one (1) occasion during any twelve (12) month period,
               provided such right shall be deemed to have been used only upon a
               registration statement on Form S-3, or successor form, becoming
               and remaining effective in accordance with such request and the
               provisions hereof.

           (b) Upon a request pursuant to Section 7.2(a), ABIOMED will use
               commercially reasonable efforts as soon as practicable thereafter
               to prepare and file a registration statement on the appropriate
               form covering such Shares. Neither ABIOMED nor any Other Holder
               may include any securities in any registration statement
               requested pursuant to this Section 7.2 which relates to an
               underwritten offering unless the underwriter or underwriters
               managing the offering shall determine and advise in writing that
               such inclusion will not interfere with the marketing of the
               securities to be offered by the requesting Holder or Holders. Any
               Holder or Holders intending to request a registration pursuant to
               Section 7.2(a) shall notify each other Holder of such request at
               least thirty (30) days prior to making the request and shall
               permit each such other Holder to join such request provided that
               such other Holder, within fifteen (15) days of receipt of such

                                       12

 
               notification, so indicates his or her intention in writing to the
               Holder or Holders from which such notification was received.
               ABIOMED, if requested, shall provide reasonable assistance in
               such notification process. If the underwriter managing such an
               offering shall determine that the number of Shares proposed to be
               included would interfere with the marketing of the same, then the
               number of Shares proposed to be included in such registration
               statement shall be reduced to the extent deemed appropriate by
               such managing underwriter pro rata among the Holders joining in
               such request in proportion to the number of Shares then held by
               each, giving effect to the provisions of the last two sentences
               of Section 7.3 below. ABIOMED shall have the right once per
               request to defer for a reasonable period (not to exceed six (6)
               months) the filing of any registration statement requested
               hereunder if, in the reasonable judgment of ABIOMED's Board of
               Directors, such registration would materially interfere with or
               materially and adversely affect the aftermarket of any recently
               completed public offering, or any then existing negotiations for
               financing arrangements of ABIOMED, or any material business
               transaction then pending or being negotiated, or any arrangement
               or plan of ABIOMED, then pending or being negotiated in good
               faith, relating to any acquisition, disposition, merger or
               similar transaction.

     7.3.  Incidental Registration.
           ----------------------- 

     If ABIOMED for itself or any of its security holders shall at any time or
times after the first anniversary of the date hereof and prior to the seventh
anniversary of the date hereof determine to register under the Securities Act
any shares of Common Stock in an underwritten public offering (other than (a)
the registration of an offer and sale of securities to employees of, or other
persons providing services to ABIOMED pursuant to an employee or similar benefit
plan, registered on Form S-8 or comparable form; or (b) relating to a merger,
acquisition or other transaction of the type described in Rule 145 under the
Securities Act or comparable rule, registered on Form S-4 or similar form),
ABIOMED will notify each Holder in each case of such determination at least
twenty (20) days prior to the filing of such registration statement, and upon
the request of a Holder given in writing within ten (10) days after the date of
such notice, ABIOMED will use commercially reasonable efforts as soon as
practicable thereafter to cause any of the Shares specified by such Holder to be
included in such registration statement.  Notwithstanding the foregoing, if the
managing underwriter determines and advises in writing that the inclusion of all
Shares of such requesting Holders and all shares of ABIOMED's Common Stock to be
offered by ABIOMED and by Other Holders, whether covered by requests for
registration or otherwise included, would interfere with the marketing of the
securities to be sold by ABIOMED, or if the registration is at the request of a
person or persons with a right to require registration, by that person or
persons, then the number of shares of Common Stock otherwise to be included in
the registration statement by Holders and Other Holders shall be reduced as
follows: (i) there shall first be excluded shares proposed to be included by
Other Holders not possessing legal rights to include the same pursuant to this
section or any similar provision; and (ii) any further reduction shall be pro
rata among such Holders and Other Holders

                                       13

 
(having such legal rights) in proportion to the number of shares as to which
registration is requested by each; provided, however, that there shall be no
reduction in the number of shares to be included therein (x) by ABIOMED or (y)
if the registration is at the request of a person or persons with a right to
require such registration, by that person or persons. For purposes of making any
such reduction, each holder (whether a Holder or Other Holder) which is a
partnership, together with the affiliates, partners and retired partners of such
holder, the estates and family members of any such partners and retired partners
and of their spouses, and any trusts for the benefit of any of the foregoing
persons shall be deemed to be a single holder and any pro rata reduction with
respect to such holder shall be based upon the aggregate amount of Shares sought
to be sold by all entities and individuals so included in such holder, and the
aggregate reduction so allocated to such holder shall be allocated among the
entities and individuals included in such holder in such manner as such
partnership may reasonably determine. If the managing underwriter determines and
advises in writing that the inclusion in the registration statement of any
shares of Common Stock to be sold by stockholders of ABIOMED would interfere
with the marketing of the securities to be sold by ABIOMED, no notice need be
given to any Holder pursuant to the first sentence of this section and no Holder
will have the right to include its Shares in such registration statement.

     7.4.  Conditions of Obligations to Register Shares.
           -------------------------------------------- 

     As conditions to ABIOMED's obligation hereunder to cause a registration
statement to be filed or Shares to be included in a registration statement, the
Holder shall provide such information and execute such documents as may
reasonably be required in connection with such registration.

     7.5.  Registration Procedures.
           ----------------------- 

     If and whenever ABIOMED is required by the provisions of this Article 7 to
use commercially reasonable efforts to include any of the Shares in a
registration statement filed under the Securities Act, ABIOMED shall as
expeditiously as possible:

           (a) Prepare and file with the SEC a registration statement with
               respect to such Shares and use commercially reasonable efforts to
               cause such registration statement to become effective.

           (b) Prepare and file with the SEC such amendments and supplements to
               such registration statement and the prospectus used in connection
               therewith as may be necessary to keep such registration statement
               effective until the Shares covered thereunder have been sold.

           (c) Secure the designation and quotation of the Shares on Nasdaq or
               any national securities exchange on which the Common Stock is
               then listed.

           (d) Furnish to each Holder such number of copies of the prospectus
               contained in such registration statement (including each
               preliminary prospectus), in conformity with the requirements of
               the Securities Act, and such other 

                                       14

 
               documents as such Holder may reasonably request in order to
               facilitate the disposition of the Shares owned by such Holder.

           (e) Use commercially reasonable efforts to register or qualify the
               Shares covered by such registration statement under the
               securities or "blue sky" laws of such jurisdictions as each
               selling Holder shall reasonably request, and do any and all other
               acts and things which may be reasonably necessary or advisable to
               enable such Holder to consummate the disposition of the Shares
               owned by such Holder in such jurisdictions during the period
               specified in Section 7.5(b), provided that ABIOMED shall not be
               required in connection herewith to execute a general consent to
               service of process in any jurisdiction.

           (f) Notify each Holder immediately of any Shares covered by such
               registration statement at any time when a prospectus relating
               thereto is required to be delivered under the Securities Act of
               the happening of any event as a result of which the prospectus
               contained in such 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 the light of the
               circumstances then existing, and as promptly as practicable,
               prepare, file and furnish to the Holder a reasonable number of
               copies of a supplement or an amendment to such prospectus as may
               be necessary so that such prospectus does not contain 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; provided, however, that ABIOMED may delay preparing,
               filing and distributing any such supplement or amendment if
               ABIOMED determines in good faith that such supplement or
               amendment might, in the reasonable judgment of ABIOMED (i)
               interfere with or affect the negotiation or completion of a
               transaction that is being contemplated by ABIOMED (whether or not
               a final decision has been made to undertake such transaction) or
               (ii) involve initial or continuing disclosure obligations that
               are not in the best interests of ABIOMED's stockholders at such
               time; provided, further, that (x) ABIOMED will give notice (a
               "Standstill Notice") of any such delay no less than five (5)
               ------------------                                          
               business days prior to such delay, (y) such delay shall not
               extend for a period of more than fifteen (15) business days
               without the written consent of the Holder and (z) ABIOMED may
               utilize such delay no more than once in each calendar year.  Each
               Holder agrees, upon receipt of a Standstill Notice, forthwith to
               cease making offers and sales of the Shares pursuant to the
               registration statement or deliveries of the prospectus contained
               therein and to return to ABIOMED, for modification and exchange,
               the copies of such prospectus not theretofore delivered by such
               Holder; provided that ABIOMED shall forthwith prepare and deliver
               to such Holder after such delay a reasonable

                                       15

 
               number of copies of any supplement to or amendment of such
               prospectus that may be necessary so that such prospectus does 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.

           (g) Use commercially reasonable efforts to prevent the issuance of
               any stop order or other order suspending the effectiveness of
               such registration statement and, if such an order is issued, to
               obtain the withdrawal at the earliest possible time and to notify
               the Holder of the issuance of such order and the resolution
               thereof.

           (h) Furnish to the Holder and any Underwriter of the Holder's Shares,
               on the date that such registration statement becomes effective,
               (i) an opinion, dated such date, of outside counsel representing
               ABIOMED (and reasonably acceptable to the Holder) addressed to
               the Holder as to the effectiveness of the registration statement
               and its compliance as to form with the requirements of the
               Securities Act and such other matters as may be reasonably
               requested by the Holder (including, if such registration
               statement relates to an underwritten public offering, such
               additional matters as are customarily included in opinions
               delivered by company counsel in underwritten public offerings)
               and (ii) in the case of an underwriting, a letter, dated such
               date, from ABIOMED's independent certified public accountants, in
               form and substance as is customarily given by independent
               certified public accounts to underwriters in an underwritten
               public offering, addressed to the underwriters, if any, and to
               the Holder.

           (i) Subject to the Holder entering into a confidentiality agreement
               reasonably acceptable to ABIOMED, provide the Holder and its
               representatives the opportunity to conduct a reasonable inquiry
               of ABIOMED's financial and other records during normal business
               hours and make available its officers, directors and employees
               for questions regarding information which the Holder may
               reasonably request in order to fulfill any due diligence
               obligation on its part.

           (j) Permit counsel for the Holder to review such registration
               statement and all amendments and supplements thereto a reasonable
               period of time prior to the filing thereof with the SEC.

           (k) In the event of an underwritten public offering of the Shares,
               enter into and perform its obligations under an underwriting
               agreement, in usual and customary form reasonably acceptable to
               ABIOMED, with the

                                       16

 
               underwriters of such offering and to use its best efforts to
               cause the conditions to the underwriters' performance thereunder
               to be met.

     7.6.  Description of Expenses.
           ----------------------- 

     All expenses incurred by ABIOMED in complying with any of the foregoing
provisions of this Section 7, including without limitation all federal and state
registration, qualification and filing fees, printing expenses, fees and
disbursements of counsel to ABIOMED, and accountants' fees and expenses incident
to or required by any such registration are herein called "Registration
                                                           ------------
Expenses."  All underwriting discounts and selling commissions applicable to the
sale of Shares hereunder and the fees and disbursements of one counsel to the
Holders with respect to any registration of the Shares hereunder are herein
called "Selling Expenses."  If ABIOMED is required by the provisions of this
        ----------------                                                    
Article 7 to use commercially reasonable efforts to effect the registration of
any of the Shares under the Securities Act, the Registration Expenses and
Selling Expenses in connection with such registration shall be borne as follows:

           (a) All Registration Expenses shall be borne by ABIOMED.

           (b) Selling Expenses shall be borne pro rata among the Holders
               participating in the registration, except that each Holder shall
               bear the expenses of any separate counsel retained by it.

     7.7.  Indemnification.
           --------------- 

     In the event that ABIOMED registers under the Securities Act any Shares
held by a Holder:

           (a) ABIOMED agrees to indemnify and hold harmless such Holder, each
               person, if any, who controls such Holder within the meaning of
               the Securities Act, any Underwriter offering or selling the
               Holder's Shares and any person controlling such Underwriter,
               against any and all loss, liability or expense arising out of or
               based upon any untrue statement or alleged untrue statement of a
               material fact in any related registration statement, prospectus
               or preliminary prospectus or any omission or alleged omission of
               any material fact required to be stated therein or necessary to
               make the statements therein, in light of the circumstances under
               which they were made, not misleading, unless such statement or
               omission was (i) made in reliance upon information furnished in
               writing by any such Holder, Underwriter or controlling person
               specifically for inclusion therein or (ii) contained in a
               preliminary prospectus and corrected in a final or amended
               prospectus if such Holder, Underwriter or controlling person
               received notice of such final or amended prospectus prior to the
               effective date of the registration statement but failed to
               deliver a copy of the final or amended prospectus at or prior to
               the confirmation of the sale of the Shares to the person
               asserting such loss, claim, damage or liability, in any case
               where such delivery is required by the Securities Act.

                                       17

 
           (b) The obligations of ABIOMED under Sections 7.2 and 7.3 with
               respect to any Holder are subject to the following conditions:
               (i) that each Holder whose Shares are to be included in any
               registration referred to in this Article 7 agrees, in writing,
               prior to the filing of such registration or filing, to indemnify
               and hold harmless ABIOMED and each person, if any, who controls
               ABIOMED within the meaning of the Securities Act, against any and
               all loss, liability or expense arising out of or based upon any
               untrue statement or alleged untrue statement of a material fact
               in any related registration statement, prospectus or preliminary
               prospectus or any omission or alleged omission of any material
               fact required to be stated therein or necessary to make the
               statements therein not misleading, but only with reference to
               statements or omissions made in reliance upon a statement in
               writing furnished by or on behalf of such Holder for inclusion
               therein; provided, however, that the liability of each Holder to
               so indemnify shall be limited to the amount received by such
               Holder on the sale of his or her Shares pursuant to such
               registration statement, and (ii) if such registration relates to
               an underwritten public offering by ABIOMED, that each such Holder
               enters into an underwriting agreement in usual and standard form
               (including a "lock-up" not exceeding 180 days of Shares not being
               sold in the underwritten offering) respecting such offering and
               uses its best reasonable efforts to cause the conditions to the
               Underwriters' performance thereunder to be met.

           (c) Each Party entitled to indemnification under this Section 7.7
               (the "Indemnified Party") shall give notice to the party required
                ----------------------    
               to provide indemnification (the "Indemnifying Party") promptly
                                                ------------------
               after such Indemnified Party has actual knowledge of any claim as
               to which indemnity may be sought, and shall permit the
               Indemnifying Party to assume the defense of any such claim or any
               litigation resulting therefrom; provided that counsel for the
               Indemnifying Party, who shall conduct the defense of such claim
               or litigation, shall be approved by the Indemnified Party (whose
               approval shall not be unreasonably withheld); 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 under this Section 7.7 unless and to the extent
               that such failure results in the forfeiture of substantive rights
               or defenses by the Indemnifying Party. The Indemnified Party may
               participate in such defense at such party's expense; provided,
               however, that the Indemnifying Party shall pay such expense if,
               in the opinion of counsel to the Indemnified Party,
               representation of such Indemnified Party by the counsel retained
               by the Indemnifying Party would be inappropriate due to actual or
               potential differing interests between the Indemnified Party and
               any other party represented by such counsel. No Indemnifying
               Party, in the defense of any such claim or litigation shall,
               except with the consent of each Indemnified Party, consent to
               entry of any judgment or enter into any settlement that does not
               include

                                       18

 
               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 and the
               Indemnifying Party shall not be required to indemnify any
               Indemnified Party for any amount paid or payable by such
               Indemnified Party in settlement of any claim or litigation
               without such consent of the Indemnifying Party, which consent
               shall not be unreasonable withheld.

                          ARTICLE 8.  CONFIDENTIALITY



     In connection with the due diligence investigation of ABIOMED by Genzyme
and Genzyme's status as a substantial stockholder of ABIOMED and in the course
of discussing projects in the field of minimally invasive cardiac surgery that
the Parties may jointly develop, fund and commercialize, the Parties acknowledge
that they have been or may be given access to confidential information of the
other Party.  For purposes of this Agreement, the term "Confidential
Information" means any information relating to the scientific and business
affairs of either Party, regardless of whether such information is specifically
designated as confidential and regardless of whether such information is in
written, oral, electronic, or other form.  Such Confidential Information may
include, without limitation, trade secrets, know-how, inventions, technical data
or specifications, testing methods, business or financial information, research
and development activities, product and marketing plans, and customer and
supplier information.

     8.1.  Non-Disclosure Obligations.
           -------------------------- 

     With respect to all Confidential Information furnished by one party (the
"Disclosing Party") to the other (the "Receiving Party"), the Receiving Party
- -----------------                      ---------------                       
agrees that it shall:

           (a) maintain such Confidential Information in strict confidence, at
               least to the same extent as the Receiving Party maintains the
               confidence of its own information of like nature;

           (b) not disclose or permit the disclosure of such Confidential
               Information to any persons other than to its directors, officers,
               employees, agents, consultants and service providers who need to
               know such Confidential Information and who are obligated to
               maintain the confidential nature of such Confidential
               Information;

           (c) use such Confidential Information only for purposes related to
               the ongoing business relationship between the Parties and not use
               any Confidential Information for its own benefit or for the
               benefit of any other person or business entity; and

           (d) allow its directors, officers, employees, agents, and other
               representatives to reproduce the Confidential Information only to
               the extent necessary to effect the purposes set forth herein,
               with all such reproductions being considered Confidential
               Information.

                                      19


 
     8.2.  Exceptions to Non-Disclosure Obligations.
           ---------------------------------------- 

     The obligations of the Receiving Party under Section 8.1 above shall not
apply to the extent that the Receiving Party can demonstrate (with the Receiving
Party having the burden of proof) that certain Confidential Information:

           (a) was in the public domain prior to the time of its disclosure;

           (b) entered the public domain after the time of its disclosure
               through means other than an unauthorized disclosure resulting
               from an act or omission by the Receiving Party;

           (c) was independently developed or discovered by the Receiving Party
               without use of the Confidential Information;

           (d) is or was disclosed to the Receiving Party at any time, whether
               prior to or after the time of its disclosure under this
               Agreement, by a third party having no obligation of
               confidentiality with respect to such Confidential Information; or

           (e) is required to be disclosed to comply with applicable laws or
               regulations, or with a court or administrative order, provided
               that the Disclosing Party receives prior written notice of such
               disclosure to permit it to seek a protective order against such
               disclosure, and in the absence of such protective order, that the
               Receiving Party takes all reasonable and lawful actions to obtain
               confidential treatment for such disclosure and, if possible, to
               minimize the extent of such disclosure.

     8.3.  Ownership of Confidential Information.
           ------------------------------------- 

     The Receiving Party agrees that the Disclosing Party (or any third party
entrusting its own Confidential Information to the Disclosing Party) is and
shall remain the exclusive owner of the Confidential Information disclosed by
the Disclosing Party and all patent, copyright, trademark, trade secret, and
other intellectual property rights in such Confidential Information or arising
therefrom.  No option, license, or conveyance of such rights to the Receiving
Party is granted or implied under this Agreement.  If any such rights are to be
granted to the Receiving Party, such grant shall be expressly set forth in a
separate written instrument.

     8.4.  Destruction of Confidential Information.
           --------------------------------------- 

     Upon the later of (a) transfer of all of the Shares or (b) the termination
by either Party of any ensuing business arrangement between the Parties that is
conducted without the benefit of a further agreement governing the treatment of
Confidential Information, the Receiving Party shall return to the Disclosing
Party all originals, copies, and summaries of documents, materials, and other
tangible manifestations of Confidential Information in any form or media,
including formal and informal notes and memoranda, in the possession or control
of the Receiving Party, except 
 
                                      20

 
that the Receiving Party may retain one copy of such Confidential Information in
the possession of its legal counsel solely for the purpose of monitoring its
obligations under this Agreement.

     8.5.  Material Inside Information.
           --------------------------- 

     The Receiving Party further acknowledges that it may receive material
inside information regarding the Disclosing Party that has not been generally
disclosed to the public in the course of its investigation and agrees to treat
such information as Confidential Information.  The Receiving Party further
understands that if it receives such material inside information, it may not
trade, directly or indirectly, in the securities of the Disclosing Party until
such time as such information is no longer material or is otherwise disclosed to
the public.

     8.6.  Terms of this Agreement.
           ----------------------- 

     The Parties agree that the public announcement of the execution of this
Agreement shall take the form of a press release mutually agreeable to the
Parties and, from and after the date hereof, each Party shall be entitled to
make or publish any statement limited to the contents of such press release.
Except as permitted by the foregoing provisions, each Party hereby agrees not to
disclose any terms or conditions of this Agreement to any third party without
the prior consent of the other Party; provided, however, that each Party will
give the other Party the opportunity to review and comment on any disclosure
that may be required by law.

                ARTICLE 9.  JOINT DEVELOPMENT AND COLLABORATIONS

     ABIOMED and Genzyme shall continue to attempt diligently to identify
projects in the field of minimally invasive cardiac surgery that the Parties can
jointly develop, fund and commercialize.

                           ARTICLE 10.  MISCELLANEOUS


     10.1. Assignment.
           ---------- 

     This Agreement may not be assigned or otherwise transferred by any Party
without the consent of the other Party, which consent shall not be unreasonably
withheld.  Notwithstanding the foregoing, Genzyme's rights under Article 7 shall
inure to the benefit of each Holder (as defined in Section 7.1) of the Shares.
Any purported assignment in violation of this Section 10.1 shall be void.  Any
permitted assignee shall assume all obligations of its assignor under this
Agreement in writing.

     10.2  Severability.
           ------------ 

     Each Party hereby agrees that it does not intend to violate any public
policy, statutory or common laws, rules, regulations, treaty or decision of any
government agency or executive body thereof of any country or community or
association of countries.  Should one or more provisions of this Agreement be or
become invalid, the Parties hereto shall substitute, by mutual consent, valid
provisions for such invalid provisions, which valid provisions in their economic
effect are 

                                       21

 
sufficiently similar to the invalid provisions that it can be reasonably assumed
that the Parties would have entered into this Agreement with such valid
provisions. In case such valid provisions cannot be agreed upon, the invalidity
of one or several provisions of this Agreement shall not affect the validity of
this Agreement as a whole, unless the invalid provisions are of such essential
importance to this Agreement that it is to be reasonably assumed that the
Parties would not have entered into this Agreement without the invalid
provisions.

     10.3. Notices.
           ------- 

     Any consent, notice or report required or permitted to be given or made
under this Agreement by one of the Parties hereto to the other shall be in
writing, delivered personally or by facsimile (and promptly confirmed by
personal delivery or courier) or courier, postage prepaid (where applicable),
addressed to such other Party at its address indicated below, or to such other
address as the addressee shall have last furnished in writing to the addressor
in accordance with this Section 10.3, and shall be effective upon receipt by the
addressee.

     If to                    ABIOMED, Inc.

     ABIOMED                  33 Cherry Hill Drive
                              Danvers, Massachusetts 01923
                              Attention: President
                              Facsimile: (508) 777-8411

     with a copy to:          Brown Rudnick Freed & Gesmer, P.C.
                              One Financial Center
                              Boston, Massachusetts 02111
                              Attention: Philip J. Flink, Esq.
                              Facsimile: (617) 856-8201

     If to                    Genzyme Corporation
     Genzyme:                 One Kendall Square
                              Cambridge, Massachusetts 02139
                              Attention: President
                              Facsimile: (617) 374-7423

     with a copy to:          Genzyme Corporation
                              One Kendall Square
                              Cambridge, Massachusetts 02139
                              Attention: Chief Legal Counsel
                              Facsimile: (617) 252-7553

     10.4. Applicable Law.
           -------------- 

     This Agreement shall be governed by and construed in accordance with the
laws of the Commonwealth of Massachusetts.

     10.5. Entire Agreement.
           ---------------- 

                                       22

 
     This Agreement contains the entire understanding of the Parties with
respect to the subject matter hereof.  All express or implied agreements and
understandings, either oral or written, heretofore made are expressly merged in
and made a part of this Agreement.  This Agreement may be amended, or any term
hereof modified, only by a written instrument duly executed by the Parties.
Each of the Parties hereby acknowledges that this Agreement is the result of
mutual negotiation and therefore any ambiguity in their respective terms shall
not be construed against the drafting Party.

     10.6. Headings.
           -------- 

     The captions to the several Articles and Sections hereof are not a part of
this Agreement, but are merely guides or labels to assist in locating and
reading the several Articles and Sections hereof.

     10.7. Counterparts.
           ------------ 

     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.

     IN WITNESS WHEREOF, the Parties have executed this Agreement as of the date
first set forth above.

                                  ABIOMED, INC.


                                  By:/s/ David M. Lederman
                                     -----------------------------------------
                                  
                                  Title:______________________________________
                                        President and Chief Executive Officer

                                        GENZYME CORPORATION


                                        By:/s/ Peter Wirth
                                           -----------------------------------
                                               Peter Wirth

                                        Title:________________________________
                                              Executive Vice President

                                       23