February 16, 2000


Jay Caplan
Thermo Cardiosystems Inc.


Dear Jay:

As we have discussed, Thermo Electron Corporation has announced a reorganization
of the company in which certain of the company's assets, including those of
Thermo Cardiosystems Inc., will be sold. We recognize that your past
contributions have been integral to the success of the company and that your
continued involvement will be necessary in order to facilitate the sale of
Thermo Cardiosystems Inc. and to assure a smooth transition for a potential
buyer.

In order to provide an incentive for you to remain with the company through the
completion of the sale, we will pay you a retention bonus

RETENTION BONUS
---------------

The retention bonus payable to you shall be equal to 100% of your annual base
salary.

This retention bonus will be paid to you in one lump sum on or before ninety
(90) days following the closing date, or January 1, 2002 whichever occurs first.


TERMS OF AGREEMENT
------------------

     1.  Thermo Cardiosystems Inc. agrees to continue to employ you on the same
         terms and with the same benefits you currently enjoy as an
         employee-at-will. In return, you agree to remain in such employ and to
         continue to devote your full time and best efforts to Thermo
         Cardiosystems Inc. as an employee-at-will until the closing date of the
         sale of Thermo Cardiosystems Inc..

     2.  You understand that Thermo Cardiosystems Inc. retains the right to
         terminate your services without cause (as defined below) and you retain
         the right to terminate your services for Thermo Cardiosystems Inc. at
         any time. If you terminate your employment prior to the closing date,
         or Thermo Cardiosystems Inc. terminates your employment for "cause" (as
         defined below), you will forfeit any and all payments that you would be
         entitled to under this agreement.

     3.  For the purposes of this agreement, "cause" shall be determined by the
         company in the exercise of good faith and reasonable judgment and will
         include any breach of this agreement by you or any act by you of gross
         personal misconduct, insubordination, misappropriation of funds, fraud,
         dishonesty, gross neglect of or failure to perform the duties
         reasonably required of you pursuant to this agreement or any conduct
         which is in willful violation of any applicable law or regulation
         pertaining to the business.

<PAGE>

     4.  For purposes of this agreement, we agree that Thermo Cardiosystems Inc.
         will be considered to be sold when any person or entity, other than a
         person or entity affiliated with Thermo Electron, purchases at least
         fifty percent (50%) of the assets of the business, whether through a
         purchase of the business or a purchase of the company of which the
         business is a part.

     5.  You understand that all payments made under this agreement are subject
         to appropriate federal, state, city or other tax withholding
         requirements.

     6.  You acknowledge that this agreement supersedes any prior agreements or
         understandings oral or written between you and Thermo Cardiosystems
         Inc. pertaining to any incentive payments being offered to employees of
         businesses being sold in connection with the reorganization and that
         this agreement constitutes the entire agreement between us.

On behalf of Thermo Electron and Thermo Cardiosystems Inc., I thank you for your
continued assistance and support. If you have any questions regarding any of the
terms of this agreement, please do not hesitate to contact me.

Once you have read and understood the terms of this agreement, please indicate
your agreement by signing below on the line above your typewritten name, make a
copy for your records and return the original document to me.

                                                         Very truly yours,



                                                         John T. Keiser
                                                         COO, Thermo Electron
Accepted and agreed:


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