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                                                                   EXHIBIT 10.30

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SILICON VALLEY BANK

                           AMENDMENT TO LOAN DOCUMENTS


BORROWER:   QUINTON INSTRUMENT COMPANY

DATE:       MAY 31, 2000

      THIS AMENDMENT TO LOAN DOCUMENTS is entered into between SILICON VALLEY
BANK ("Silicon") and the borrower named above ("Borrower").

      The Parties agree to amend the Loan and Security Agreement between them,
dated June 5, 1998, (as amended, if at all, the "Loan Agreement"), as follows,
effective as of the date hereof. (Capitalized terms used but not defined in this
Amendment shall have the meanings set forth in the Loan Agreement.)

      1.    MODIFIED SCHEDULED MATURITY DATE.

            (a)   Section 6.1 of the Loan Agreement is amended and restated in
                  its entirety to read as follows:

                        "6.1 MATURITY DATE. This Agreement shall continue in
                  effect until the maturity date set forth on the Schedule (the
                  "Maturity Date"), subject to Sections 6.2 and 6.3 below."

            (b)   Section 4 of the Schedule is amended and restated in its
                  entirety to read as follows:

                  "4. MATURITY DATE

                        (Section 6.1):    June 5, 2001."

      2.    MODIFIED CREDIT LIMIT. Section 1 of the Schedule is amended and
restated in its entirety to read as follows:

            "1. INTEREST RATE

            (Section 1.1):    Revolving Loans. Loans (the `Revolving Loans') in
                              an amount up to the lesser of $12,000,000, or the
                              sum of (1) and (2) below:

                                    (a) Accounts Loans. 80% of the amount of
                                    Borrower's Eligible Receivables (as defined
                                    in Section 8 above), plus

                                    (b) Inventory Loans. an amount not to exceed
                                    the lesser of:

                                          (i)   20% of the value of Borrower's
                                                Eligible Inventory ( as defined
                                                in Section 8 above), calculated
                                                at the lower of cost or market
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                    SILICON VALLEY BANK              AMENDMENT TO LOAN AGREEMENT
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                                                value and determined on a
                                                first-in, first-out basis, or

                                          (ii)  an amount equal to 40% of
                                                Borrower's Eligible Receivables,
                                                or

                                          (iii) $2,500,000,

                                          provided that Silicon may revise the
                                          advance rates with respect to
                                          Inventory set forth above in Silicon's
                                          good faith business judgment based on
                                          independent third-party appraisals of
                                          the Inventory made by appraisers
                                          selected by Silicon."

      3.    MODIFIED INTEREST RATE. Section 2 of the Schedule is amended and
restated in its entirety to read as follows:

            "2.  INTEREST RATE

            (Section 1.2):

                              Revolving Loans: A rate equal to the "Prime Rate"
                              in effect from time to time plus 1.0% per annum.

                              Interest shall be calculated on the basis of a
                              360-day year for the actual number of days
                              elapsed. "Prime Rate" means the rate announced
                              from time to time by Silicon as its "prime rate;"
                              it is a base rate upon which other rates charged
                              by Silicon are based, and it is not necessarily
                              the best rate available at Silicon. The interest
                              rate applicable to the Obligations shall change on
                              each date there is a change in the Prime Rate."

      4.    NEW FINANCIAL COVENANT. Section 5 of the Schedule is hereby amended
and restated in its entirety to read as follows:

            "5. FINANCIAL COVENANT

            (Section 5.1):    Borrower shall comply with the following covenant.
                              Compliance shall be determined as of the end of
                              each month:

                              MINIMUM TANGIBLE

                              NET WORTH: Borrower shall maintain a Tangible Net
                              Worth of not less than $5,000,000.

                              DEFINITIONS. For purposes of the foregoing
                              financial covenants, the following term shall have
                              the following meaning:

                              "Liabilities" shall have the meaning ascribed
                              thereto by generally accepted accounting
                              principles. "Tangible Net Worth" shall mean the
                              excess of total assets over total liabilities,
                              determined in accordance with generally accepted
                              accounting principles, with the following
                              adjustments:

                                    (A) there shall be excluded from assets: (i)
                              notes, accounts receivable and other obligations
                              owing to the


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                    SILICON VALLEY BANK              AMENDMENT TO LOAN AGREEMENT
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                              Borrower from its officers or other Affiliates,
                              and (ii) all assets which would be classified as
                              intangible assets under generally accepted
                              accounting principles, including without
                              limitation goodwill, licenses, patents,
                              trademarks, trade names, copyrights, capitalized
                              software and organizational costs, licenses and
                              franchises

                                    (B) there shall be excluded from
                              liabilities: all indebtedness which is
                              subordinated to the Obligations under a
                              subordination agreement in form specified by
                              Silicon or by language in the instrument
                              evidencing the indebtedness which is acceptable to
                              Silicon in its discretion."

      5.    FEE. In consideration of Silicon's execution of this Amendment,
Borrower agrees to pay Silicon a fee in the amount of $120,000, concurrently
with the execution of this Amendment, which fee shall be deemed fully earned
upon Silicon's execution of this Amendment, and may be charged to any account of
Borrower maintained with Silicon.

      6.    REPRESENTATIONS TRUE. Borrower represents and warrants to Silicon
that all representations and warranties set forth in the Loan Agreement, as
amended hereby, are true and correct.

      7.    GENERAL PROVISIONS. This Amendment, the Loan Agreement, any prior
written amendments to the Loan Agreement signed by Silicon and Borrower, and the
other written documents and agreements between Silicon and Borrower set forth in
full all of the representations and agreements of the parties with respect to
the subject matter hereof and supersede all prior discussions, representations,
agreements and understandings between the parties with respect to the subject
hereof. Except as herein expressly amended, all of the terms and provisions of
the Loan Agreement, and all other documents and agreements between Silicon and
Borrower shall continue in full force and effect and the same are hereby
ratified and confirmed.

BORROWER:                                SILICON:

QUINTON INSTRUMENT COMPANY               SILICON VALLEY BANK

By      /s/ Michael Blomeyer             By      /s/ Silicon Valley Bank
    --------------------------------         --------------------------------
    President or Vice President          Title                            SVP
                                              -------------------------------

By      /s/ John Hinson
    --------------------------------
    Secretary or Ass't Secretary


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                    SILICON VALLEY BANK              AMENDMENT TO LOAN AGREEMENT
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Acknowledged and Agreed:

GREYROCK CAPITAL,
A DIVISION OF BANC OF AMERICA
COMMERCIAL FINANCE
CORPORATION

By   /s/ Greyrock Capital
  ----------------------------
Title V.P.
     -------------------------


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                    SILICON VALLEY BANK              AMENDMENT TO LOAN AGREEMENT
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                                     CONSENT

      The undersigned acknowledge that their consent to the foregoing Agreement
is not required, but the undersigned nevertheless do hereby consent to the
foregoing Agreement and to the documents and agreements referred to therein and
to all future modifications and amendments thereto, and any termination thereof,
and to any and all other present and future documents and agreements between or
among the foregoing parties. Nothing herein shall in any way limit any of the
terms or provisions of the Continuing Guaranties of the undersigned, all of
which are hereby ratified and affirmed.

                                    QIC HOLDING CORP.


                                    By:     /s/ John Hinson
                                       ---------------------------------
                                    Title:  Secretary
                                          ------------------------------


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