1 THIRD AMENDMENT TO AMENDED AND RESTATED CREDIT AGREEMENT This THIRD AMENDMENT TO AMENDED AND RESTATED CREDIT AGREEMENT (this "AMENDMENT") dated as of July 24, 1998, is by and among Raytel Medical Corporation (the "BORROWER"), BankBoston, N.A.,...

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THIRD AMENDMENT TO AMENDED
AND RESTATED CREDIT AGREEMENT

This THIRD AMENDMENT TO AMENDED AND RESTATED CREDIT AGREEMENT (this
"AMENDMENT") dated as of July 24, 1998, is by and among Raytel Medical
Corporation (the "BORROWER"), BankBoston, N.A., formerly known as Bank of Boston
Connecticut ("BANKBOSTON") and Banque Paribas (collectively, the "BANKS") and
BankBoston, as agent for the Banks (in such capacity, the "AGENT").

W I T N E S S E T H:

WHEREAS, the Borrower, the Banks and the Agent entered into a certain
Amended and Restated Credit Agreement dated as of August 14, 1996, as amended by
the First Amendment to Amended and Restated Credit Agreement dated as of June 4,
1997 and by the Second Amendment to Amended and Restated Credit Agreement dated
as of September 26, 1997 (as amended from time to time, the "CREDIT AGREEMENT");
and

WHEREAS, the Borrower has requested that the Credit Agreement be amended
in certain respects; and

WHEREAS, the Agent and the Banks have agreed to amend the Credit
Agreement on the terms and conditions set forth herein.

NOW, THEREFORE, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree as
follows:

SECTION 1. DEFINITIONS. Capitalized terms used herein without definition
that are defined in the Credit Agreement shall have the same meanings herein as
therein.

SECTION 2. REPRESENTATIONS AND WARRANTIES. The Borrower hereby repeats
on and as of the date hereof the representations and warranties made by it in
the Credit Agreement, provided that all references therein to the Credit
Agreement shall refer to the Credit Agreement as amended hereby.

SECTION 3. RATIFICATION, ETC. Except as expressly amended hereby, the
Credit Agreement and all documents, instruments and agreements related thereto
are hereby ratified and confirmed in all respects and shall continue in full
force and effect. This Amendment and the Credit Agreement shall hereafter be
read and construed together as a single document, and all references in the
Credit Agreement or any related agreement or instrument to the Credit Agreement
shall hereafter refer to the Credit Agreement as amended by this Amendment.

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SECTION 4. AMENDMENTS TO CREDIT AGREEMENT.

SECTION 4.1. AMENDMENT TO SECTION 10.3. Section 10.3 of the
Credit Agreement is hereby amended in its entirety to read as follows:

"SECTION 10.3 CONSOLIDATED TOTAL FUNDED DEBT TO EBITDA. The
Borrower will not permit the ratio of Consolidated Total Funded Debt of the
Borrower and its Subsidiaries to Earnings Before Interest and Taxes,
Depreciation and Amortization of the Borrower and its Subsidiaries for any
period consisting of four (4) consecutive fiscal quarters of the Borrower ending
after the Effective Date to exceed 2.5:1.0."

SECTION 4.2. AMENDMENTS TO SCHEDULE 2.

(a) The definition of "Consolidated Total Funded Debt"
appearing in Schedule 2 of the Credit Agreement is hereby amended in its
entirety to read as follows:

"Consolidated Total Funded Debt. As to any Person and
whether recourse is secured by or is otherwise available against all or
only a portion of the assets of such Person and whether or not
contingent, but without duplication:

(i) every obligation of such Person for money borrowed,

(ii) every obligation of such Person evidenced by
bonds, debentures, notes or other similar instruments,
including obligations incurred in connection with the
acquisition of property, assets or businesses,

(iii) every reimbursement obligation of such Person
with respect to letters of credit, bankers' acceptances or
similar facilities issued for the account of such Person,

(iv) every obligation of such Person issued or assumed
as the deferred purchase price of property or services
(including securities repurchase agreements but excluding
trade accounts payable or accrued liabilities arising in the
ordinary course of business which are not overdue or which
are being contested in good faith),

(v) every obligation of such Person under any
Capitalized Lease,

(vi) every obligation of such Person under any lease (a
"synthetic lease") treated as an operating lease under
generally

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accepted accounting principles and as a loan or financing
for U.S. income tax purposes,

(vii) all sales by such Person of (A) accounts or
general intangibles for money due or to become due, (B)
chattel paper, instruments or documents creating or
evidencing a right to payment of money or (C) other
receivables (collectively "receivables"), whether pursuant
to a purchase facility or otherwise, other than in
connection with the disposition of the business operations
of such Person relating thereto or a disposition of
defaulted receivables for collection and not as a financing
arrangement, and together with any obligation of such Person
to pay any discount, interest, fees, indemnities, penalties,
recourse, expenses or other amounts in connection therewith,

(viii) every obligation of such Person (an "equity
related purchase obligation") to purchase, redeem, retire or
otherwise acquire for value any shares of capital stock of
any class issued by such Person, any warrants, options or
other rights to acquire any such shares, or any rights
measured by the value of such shares, warrants, options or
other rights,

(ix) every obligation of such Person under any forward
contract, futures contract, swap, option or other financing
agreement or arrangement (including, without limitation,
caps, floors, collars and similar agreements), the value of
which is dependent upon interest rates, currency exchange
rates, commodities or other indices (a "derivative
contract"),

(x) every obligation in respect of Indebtedness of any
other entity (including any partnership in which such Person
is a general partner) to the extent that such Person is
liable therefor as a result of such Person's ownership
interest in or other relationship with such entity, except
(1) to the extent that the terms of such Indebtedness
provide that such Person is not liable therefor and such
terms are enforceable under applicable law and (2) any
obligation arising in connection with the Joint Ventures,

(xi) every obligation, contingent or otherwise, of such
Person guaranteeing, or having the economic effect of
guarantying or otherwise acting as surety for, any
obligation of a type described in any of clauses (i) through
(x) (the "primary obligation") of another Person (the
"primary obligor"), in any manner, whether directly or
indirectly, and including, without limitation, any
obligation of such Person (A) to purchase or pay (or advance
or supply funds for the

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purchase of) any security for the payment of such primary
obligation, (B) to purchase property, securities or services for
the purpose of assuring the payment of such primary obligation,
or (C) to maintain working capital, equity capital or other
financial statement condition or liquidity of the primary obligor
so as to enable the primary obligor to pay such primary
obligation.

The "amount" or "principal amount" of any Indebtedness at any
time of determination represented by (u) any Indebtedness, issued at a
price that is less than the principal amount at maturity thereof, shall
be the amount of the liability in respect thereof determined in
accordance with generally accepted accounting principles, (v) any
Capitalized Lease shall be the principal component of the aggregate of
the rentals obligation under such Capitalized Lease payable over the
term thereof that is not subject to termination by the lessee, (w) any
sale of receivables shall be the amount of unrecovered capital or
principal investment of the purchaser (other than the Borrower or any of
its wholly-owned Subsidiaries) thereof, excluding amounts representative
of yield or interest earned on such investment, (x) any synthetic lease
shall be the stipulated loss value, termination value or other
equivalent amount, (y) any derivative contract shall be the maximum
amount of any termination or loss payment required to be paid by such
Person if such derivative contract were, at the time of determination,
to be terminated by reason of any event of default or early termination
event thereunder, whether or not such event of default or early
termination event has in fact occurred and (z) any equity related
purchase obligation shall be the maximum fixed redemption or purchase
price thereof inclusive of any accrued and unpaid dividends to be
comprised in such redemption or purchase price."

(b) The following new definition of "Earnings Before Interest and Taxes,
Depreciation and Amortization" is hereby added to Schedule 2 of the Credit
Agreement in alphabetical order to read as follows:

"Earnings Before Interest and Taxes, Depreciation and
Amortization. For any period, an amount equal to the sum of (a) the
consolidated earnings (or loss) from the operations of any Person for
such period, after all expenses and other proper charges but before
payment or provision for any income taxes or interest expense for such
period, plus (b) depreciation, amortization and other non-cash charges
for such period, all determined in accordance with generally accepted
accounting principles."

SECTION 5. CONDITIONS TO EFFECTIVENESS. The effectiveness of this
Amendment is subject to the prior satisfaction, on or before the date hereof, of
the following conditions precedent (the date of such satisfaction herein
referred to as the "AMENDMENT EFFECTIVE DATE"):

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(a) Representations and Warranties. The representations and
warranties contained in paragraph 7 of the Credit Agreement shall have
been correct at and as of the date made. Such representations and
warranties shall also be correct at and as of the date thereof, except
to the extent that such representations and warranties expressly related
to a specific date or were based on facts which have changes in the
ordinary course of business, which changes, either singly or in the
aggregate, are not materially adverse.

(b) No Event of Default. There shall exist no Event of Default or
condition which, with either or both the giving of notice of the lapse
of time, would result in an Event of Default upon the execution and
delivery of this Amendment.

(c) Corporate Action. The Banks and the Agent shall have received
evidence reasonably satisfactory to the Bank and the Agent that all
requisite corporate action necessary for the valid execution, delivery
and performance by the Borrower and Subsidiaries of this Amendment and
all other instruments and documents delivered by the Borrower and
Subsidiaries in connection herewith.

(d) Delivery of Amendment. The parties hereto shall have executed
and delivered this Amendment in form and substance satisfactory to the
Banks and the Agent.

SECTION 6. EFFECTIVE DATE This Amendment shall become effective among
the parties hereto as of the Amendment Effective Date. Until the Amendment
Effective Date, the terms of the Credit Agreement prior to its amendment hereby
shall remain in full force and effect.

SECTION 7. COUNTERPARTS. This Amendment may be executed in any number of
counterparts and by different parties hereto on separate counterparts, each of
which when so executed and delivered shall be an original, but all of which
counterparts taken together shall be deemed to constitute one and the same
instrument.

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

RAYTEL MEDICAL CORPORATION

By: /s/ E. ▇▇▇▇▇▇ ▇▇▇▇▇, ▇▇.
--------------------------
Its: Chief Financial Officer

BANQUE PARIBAS, now known as Paribas

By: /s/ ▇▇▇▇▇ ▇▇▇▇▇▇
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Its: Director

BANKBOSTON, N.A.,
individually and as Agent

By: /s/ ▇▇▇▇▇▇▇▇▇▇▇ ▇▇▇▇▇▇
--------------------------
Its: Vice President

Each of the undersigned Subsidiaries acknowledges and accepts the foregoing and
ratifies and confirms in all respects such Subsidiary's obligations under the
Guarantees:

RAYTEL CARDIAC SERVICES, INC.