Checking Sensitivity and Capture on DDD Osypka Epicardial Pacemaker

Assessing Capture

• The American Heart Association recommends applying a magnet over the pacemaker generator to initiate asynchronous pacing at the programmed magnet rate, which overrides sensing functions and forces continuous pacing, and observe the ECG during magnet application to verify that each atrial pacing spike produces a visible P wave and each ventricular pacing spike produces a QRS complex 1, 2.
• For atrial capture, confirm that atrial pacing artifacts are followed by P waves with appropriate morphology and timing, and for ventricular capture, verify that ventricular pacing artifacts are followed by wide QRS complexes with appropriate morphology 2, 3.

Assessing Sensitivity

• Without magnet application, observe the baseline ECG to determine if the patient displays intrinsic rhythm or is being paced, and confirm that the pacemaker appropriately inhibits its output when sensing native atrial and ventricular activity 2, 3, 4.
• Reduce the pacing rate below the patient's intrinsic rate to allow native cardiac activity to emerge, and observe for appropriate sensing by confirming that intrinsic P waves and QRS complexes inhibit the corresponding pacemaker outputs 2, 3.

Specific Considerations for DDD Mode

• Verify that sensed atrial activity triggers ventricular pacing after the programmed AV interval when AV block is present, and confirm that the AV interval changes appropriately during magnet application if this is a programmed feature of the device 5, 6, 1, 2.
• Obtain 6-9 second ECG strips both without and with magnet application, as this duration is sufficient to demonstrate all necessary pacing parameters 1, 2, 3.
• If the Osypka pacemaker has a Threshold Margin Test or similar automated threshold assessment feature programmed "on," analyze these results during the evaluation 1, 2.