<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 annual report on Form 10-K of Quinton
      Cardiology Systems, Inc.;

            2. Based on my knowledge, this annual 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 annual report;

            3. Based on my knowledge, the financial statements, and other
      financial information included in this annual 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
      annual 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 we 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 annual 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 report our conclusions about
      the effectiveness of the disclosure controls and procedures as of the end
      of the period covered by this report based on such evaluation; and

            d) disclosed in this report any change in the registrant's internal
      control over financial reporting that occurred during the registrant's
      most recent fiscal quarter (the registrant's fourth fiscal quarter in the
      case of an annual report) 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: March 16, 2005

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