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                                                                     EXHIBIT 4.3
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                   CardioDynamics International Corporation
                       6175 Nancy Ridge Drive, Suite 300
                              San Diego, CA 92121

                                August 31, 2001



The Allen E. Paulson Living Trust
c/o Paulson Enterprises
P.O. box 9660
Rancho Santa Fe, California 92067
Attention:  J. Michael Paulson and Edward White

Ladies and Gentlemen:

Reference is made to a certain Securities Purchase Agreement dated as of August
31, 2001 (the "Purchase Agreement"), pursuant to which the Trust has agreed to
sell (the "Sale") up to five hundred thousand (500,000) shares of CardioDynamics
International Corporation (the "Company") Common Stock (the "Shares") to Pine
Ridge Financial Inc. (the "Purchaser").

As contemplated by the Purchase Agreement, the Company will enter into a
Registration Rights Agreement dated as of August 31, 2001 (the "Rights
Agreement") with the Purchaser, whereby the Company will agree to register the
Shares for resale and keep such registration statement effective for a period of
two (2) years, as more fully described in the Rights Agreement.  The Company
hereby agrees to use its best efforts to cause such registration statement to be
declared effective within 90 days following the Closing Date as such term is
defined in the Purchase Agreement.  The Trust hereby agrees to reimburse the
Company, either directly or out of escrow established in connection with the
Purchase Agreement (the "Escrow"), for all of the Company's expenses (up to a
maximum of $10,000 in the aggregate) that the Company incurs in connection with
any registration, qualification and compliance requested pursuant to the Rights
Agreement, including without limitation, all filing, registration and
qualification, and accounting fees and the fees and disbursements of its
counsel.

Further, as compensation for (i) our introduction of the Purchaser to the Trust,
(ii) fees and expenses we incurred in connection with such introduction, and
(iii) the otherwise unreimbursed fees and expenses related to the registration
of the Shares as well as the devotion of management time to and opportunity cost
associated with preparation and review of the documents associated with the Sale
and the registration and qualification of the Shares, the Trust hereby agrees to
pay to the Company, in cash at the time of the Settlement Date of the Sale as
set forth in the Purchase Agreement, either directly or out of the Escrow, a fee
equal to two percent (2%) of the gross purchase price paid by the Purchaser for
the Shares.  The Company shall refund the foregoing fee to the Trust in the
event that the Trust is required to repurchase the Shares and does so repurchase
such Shares from the Purchaser because the registration statement that the
Company has agreed to file with respect to the Shares has not been declared
effective within 90 days following the Closing Date.


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Please execute and return this letter agreement (which may be executed in
counterparts) to the undersigned to concur that (i) this sets forth the Trust's
complete and entire understanding with regards to the subjects described within,
and (ii) that this letter agreement may not be amended or modified except in a
writing executed on behalf of both the Company and the Trust.  By execution
hereof, we both further agree that this letter agreement is to be governed by
and construed in accordance with the laws of the State of California, as applied
to contracts among California residents, made and to be performed entirely
within the State of California.

                                    CardioDynamics International Corporation
                                    a California corporation

                                    By:  /s/ Michael K. Perry
                                         --------------------
                                        Name:  Michael K. Perry
                                        Title:  Chief Executive Officer

Accepted and agreed as of August 31, 2001:
The Allen E. Paulson Living Trust


By:  /s/ J. Michael Paulson
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     Name:  J. Michael Paulson, Co-Trustee


By:  /s/ Edward White
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     Name:  Edward White, Co-Trustee