Document:

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                                                                    Exhibit 10.1

    AMENDMENT NO. 3 TO SUBORDINATED NOTE AND COMMON STOCK PURCHASE AGREEMENT
    ------------------------------------------------------------------------

     Amendment No. 3 to Subordinated Note and Common Stock Purchase Agreement
dated as of April 5, 2000 by and among J.H. Whitney & Co. ("JHW"), Whitney
Subordinated Debt Fund, L.P. ("WSDF" and, together with JHW, "Whitney") and NMT
Medical, Inc. ("NMT").

     Reference is made to that certain Subordinated Note and Common Stock
Purchase Agreement, dated as of July 8, 1998 (the "Whitney Purchase Agreement"),
by and among WSDF, NMT and, for certain purposes, JHW, as amended by that
certain Amendment No. 1 dated April 14, 1999 ("Amendment No. 1") and as further
amended by that certain Amendment No. 2 dated September 13, 1999 ("Amendment No.
2") (the Whitney Purchase Agreement as so amended,  the "Amended Whitney
Purchase Agreement");

     Reference is further made to that certain Waiver and Consent Agreement
dated as of March 20, 2000 (the "Waiver Agreement"), by and among Brown Brothers
Harriman & Co. ("BBH"), NMT, certain other subsidiaries of NMT, and Whitney.

     WHEREAS, the Waiver Agreement provides, inter alia, that upon the reduction
of the principal amount outstanding under NMT's credit agreement with BBH (the
"U.S. Credit Agreement") to $2,000,000, the amount of permitted Senior
Indebtedness (as defined in the Amended Whitney Purchase Agreement) shall be
reduced to $2,000,000;

     WHEREAS, upon the closing of the Sale Transactions (as defined in the
Waiver Agreement) on April 5, 2000, the principal amount outstanding under the
U.S. Credit Agreement was reduced to $2,000,000; and

     WHEREAS, the parties now wish to memorialize the reduction of permitted
Senior Indebtedness as contemplated by the Waiver Agreement.

     NOW, THEREFORE, in consideration of the foregoing and the promises and
agreements set forth herein, the parties agree as follows:

     1.   The maximum aggregate principal amount of permitted Senior
Indebtedness (as defined in the Amended Whitney Purchase Agreement) is hereby
reduced from $13,000,000 to $2,000,000.

     2.   Except for the foregoing, all of the terms and conditions of the
Amended Whitney Purchase Agreement (as affected by the Waiver Agreement and that
certain Release of Security Interest Agreement dated as of March 20, 2000 by and
among Whitney, BBH, NMT and NMT's domestic subsidiaries) remain in full force
and effect.

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     WHEREFORE, the parties have executed this agreement as a document under
seal as of the date first written above.

WHITNEY SUBORDINATED DEBT FUND, L.P.

By: /s/ Daniel J. O'Brien
   -----------------------
   Name:  Daniel J. O'Brien
   Title: General Partner

J.H. WHITNEY & CO.

By: /s/ Daniel J. O'Brien
   ----------------------
   Name:  Daniel J. O'Brien
   Title: General Partner

NMT MEDICAL, INC.

By: /s/ William J. Knight
   ----------------------
   Name:  William J. Knight
   Title: Vice President - Finance and Administration
      and Chief Financial Officer<PAGE>

                                                                   Exhibit 10.2

                              FIRST AMENDMENT TO
                               CREDIT AGREEMENT
                               ----------------

     This FIRST AMENDMENT TO CREDIT AGREEMENT ("Amendment"), dated as of April
5, 2000, by and among NMT Medical, Inc., a Delaware corporation ("NMT"), NMT
Heart, Inc., a Delaware corporation, NMT Investments Corp., a Massachusetts
corporation, NMT NeuroSciences (International), Inc., a Delaware corporation,
NMT NeuroSciences (US), Inc., a Delaware corporation, NMT NeuroSciences (IP),
Inc., a Delaware corporation, and NMT Neurosciences Innovasive Systems, Inc., a
Florida corporation (collectively, the "Borrowers"), and Brown Brothers Harriman
& Co. (the "Lender").

     WHEREAS, the Borrowers and the Lender are parties to a certain Credit
Agreement dated as of September 13, 1999 (the "Credit Agreement") (capitalized
terms which are not defined in this Amendment shall have their respective
meanings specified in the Credit Agreement);

     WHEREAS, NMT and certain of its subsidiaries entered into purchase
agreements pursuant to which Integra Selector Corporation and Integra
Neurosciences Holdings (UK) Limited purchased on the date hereof, certain assets
of, or the capital shares in, certain subsidiaries of NMT (the "Sale
Transactions");

     WHEREAS, pursuant to a Waiver and Consent Agreement, dated as of March 20,
2000, by and among the Borrowers, the Lender, J.H. Whitney & Co. and Whitney
Subordinated Debt Fund, L.P. (the "Waiver and Consent"), the Borrowers agreed to
pay to the Lender such amount from the proceeds of the Sale Transactions as
necessary to reduce the outstanding principal balance under the Credit Agreement
to $2,000,000;

     WHEREAS, upon the reduction of the outstanding principal balance under the
Credit Agreement to $2,000,000 as contemplated by the Waiver and Consent, the
Borrowers and the Lender agreed to permanently reduce the Commitment to
$2,000,000; and

     WHEREAS, the Borrowers and the Lender desire to amend the Credit Agreement
to so reduce the Commitment.

     NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which is hereby acknowledged, the parties hereby amend the Credit
Agreement as follows:

     Section 1.  Article I.  Article I of the Credit Agreement is hereby amended
                 ---------
by deleting the definition for "Commitment" and substituting therefor the
following:

          " "Commitment" means the commitment of the Lender to make Revolving
             ----------
     Loans and to issue Letters of Credit hereunder.  The initial amount of the
     Lender's Commitment is $2,000,000."
<PAGE>

     Section 2.   Representations and Warranties.  The Borrowers hereby confirm
                  ------------------------------
to the Lender that the representations and warranties of the Borrowers set forth
in Article III of the Credit Agreement are true and correct as of the date
hereof, as if set forth herein in full, except to the extent that such
representations and warranties are no longer true and correct as a result solely
of the consummation of the Sale Transactions.

     Section 3.  No Default.  The Borrowers hereby acknowledge that there is no
                 ----------
Default or Event of Default existing under the Credit Agreement.

     Section 4.  No Other Changes.  Except as amended by this Amendment, the
                 ----------------
Credit Agreement remains in full force and effect.

     Section 5.  Counterparts.  This Amendment may be executed in any number of
                 ------------
counterparts each of which shall be an original with the same effect as if all
of the signatures to this Amendment were upon the same instrument.

     Section 6.  Miscellaneous.  This Amendment shall be governed by and
                 -------------
construed and enforced under the laws of the Commonwealth of Massachusetts.

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     IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
duly executed by their respective authorized officers as of the day and year
first above written.

                                   NMT MEDICAL, INC.

                                   By: /s/ William J. Knight
                                      ----------------------
                                      Name:  William J. Knight
                                      Title: Vice President-Finance and
                                             Administration and Chief Financial
                                             Officer

                                   NMT HEART, INC.

                                   By: /s/ William J. Knight
                                      ----------------------
                                      Name:  William J. Knight
                                      Title: Treasurer and Secretary

                                   NMT INVESTMENTS CORP.

                                   By: /s/ William J. Knight
                                      ----------------------
                                      Name:  William J. Knight
                                      Title: Treasurer and Clerk

                                   NMT NEUROSCIENCES
                                   (INTERNATIONAL), INC.

                                   By: /s/ William J. Knight
                                      ----------------------
                                      Name:  William J. Knight
                                      Title: Treasurer and Secretary

                                   NMT NEUROSCIENCES (US), INC.

                                   By: /s/ William J. Knight
                                      ----------------------
                                      Name:  William J. Knight
                                      Title: Treasurer and Secretary

                                       3
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                                   NMT NEUROSCIENCES (IP), INC.

                                   By: /s/ William J. Knight
                                       ----------------------
                                       Name:  William J. Knight
                                       Title: Treasurer and Secretary

                                   NMT NEUROSCIENCES
                                   INNOVASIVE SYSTEMS, INC.

                                   By: /s/ William J. Knight
                                       ----------------------
                                       Name:  William J. Knight
                                       Title: Treasurer and Secretary

                                   BROWN BROTHERS HARRIMAN & CO.

                                   By: /s/ Louise A. Coughlan
                                       ----------------------
                                      Name:  Louise A. Coughlan
                                      Title: Senior Vice President

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