<PAGE>

                                                                    EXHIBIT 31.2

          CERTIFICATION OF CHIEF FINANCIAL OFFICER PURSUANT TO SECTION
                    302(a) OF THE SARBANES-OXLEY ACT OF 2002

I, Michael K. Matysik, certify that:

      1.    I have reviewed this quarterly report on Form 10-Q of Quinton
            Cardiology Systems, Inc.;

      2.    Based on my knowledge, this quarterly report does not contain any
            untrue statement of a material fact or omit to state a material fact
            necessary to make the statements made, in light of the circumstances
            under which such statements were made, not misleading with respect
            to the period covered by this quarterly report;

      3.    Based on my knowledge, the financial statements, and other financial
            information included in this quarterly report, fairly present in all
            material respects the financial condition, results of operations and
            cash flows of the registrant as of, and for, the periods presented
            in this quarterly report;

      4.    The registrant's other certifying officer and I are responsible for
            establishing and maintaining disclosure controls and procedures (as
            defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal
            control over financial reporting (as defined in Exchange Act Rules
            13a-15(f) and 15d-15(f)) for the registrant and have:

            a)    designed such disclosure controls and procedures, or caused
                  such disclosure controls and procedures to be designed under
                  our supervision, to ensure that material information relating
                  to the registrant, including its consolidated subsidiaries, is
                  made known to us by others within those entities, particularly
                  during the period in which this quarterly report is being
                  prepared;

            b)    designed such internal control over financial reporting, or
                  caused such internal control over financial reporting to be
                  designed under our supervision, to provide reasonable
                  assurance regarding the reliability of financial reporting and
                  the preparation of financial statements for external purposes
                  in accordance with generally accepted accounting principles;

            c)    evaluated the effectiveness of the registrant's disclosure
                  controls and procedures and presented in this quarterly report
                  our conclusions about the effectiveness of the disclosure
                  controls and procedures, as of the end of the period covered
                  by this quarterly report based on such evaluation; and

            d)    disclosed in this quarterly report any change in the
                  registrant's internal control over financial reporting that
                  occurred during the registrant's first fiscal quarter of 2005
                  that has materially affected, or is reasonably likely to
                  materially affect, the registrant's internal control over
                  financial reporting; and

5.    The registrant's other certifying officer and I have disclosed, based on
      our most recent evaluation of internal control over financial reporting,
      to the registrant's auditors and the audit committee of registrant's board
      of directors (or persons performing the equivalent function):

            a)    all significant deficiencies and material weaknesses in the
                  design or operation of internal control over financial
                  reporting which are reasonably likely to adversely affect the
                  registrant's ability to record, process, summarize and report
                  financial information; and

            b)    any fraud, whether or not material, that involves management
                  or other employees who have a significant role in the
                  registrant's internal control over financial reporting.

Date: May 9, 2005

                                                 /s/ MICHAEL K. MATYSIK
                                                 ------------------------------
                                                 Michael K. Matysik
                                                 Chief Financial Officer