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Loss of atrial signal detection with increasing sensitivity settings: a software problem and its practical solution
G Fröhlig1, H Schwerdt, M Berg
1Medizinische Universitätsklinik, Innere Medizin III, Homburg, Germany.
Pacing and Clinical Electrophysiology : PACE
|April 1, 1991
Summary
A logic error in Cosmos II pacemakers can cause incorrect atrial signal detection. Adjusting the ventricular refractory period to under 210 msec resolves this sensing malfunction.
Area of Science:
- Biomedical Engineering
- Medical Device Technology
Background:
- The Cosmos II pacemaker is designed to sense atrial signals for proper cardiac pacing.
- Pacemaker sensitivity settings are crucial for accurately distinguishing between physiological signals and noise.
Purpose of the Study:
- To investigate a logic error in the Cosmos II pacemaker software causing apparent atrial signal malsensing.
- To identify the conditions under which this malfunction occurs and how to mitigate it.
Main Methods:
- Testing of 87 Cosmos II pacemaker units to evaluate atrial sensitivity and ventricular refractory period interactions.
- Analysis of both unipolar and bipolar system performance regarding signal sensing.
Main Results:
- A logic error caused atrial malsensing in 62% of tested units when atrial sensitivity was increased.
- The malfunction was linked to the summation of physiological signals and internal noise within a specific timing window.
- The issue was largely resolved when the ventricular refractory period was kept at or below 210 msec.
Conclusions:
- The Cosmos II pacemaker exhibits a software logic error leading to atrial malsensing under specific high sensitivity settings.
- Maintaining the ventricular refractory period at its nominal value of 200 msec is recommended to prevent this malfunction.