engleski

Sensing Shift of Sensitivity Programmable Pacemakers

Summary: The purpose of this study was to investigate the sensing timing accuracy at different sensitivity settings. One hundred eighteen patients having multiprogrammable ventricular pacemakers were programmed in VVT mode and low rate. Six-lead ECG’s were recorded at every possible sensitivity setting. Alteration of the time interval between onset of QRS wave and pacemaker spike was measured and named as the “ventricular sensing shift interval" (SSI). Thirty-one patients with DDD pacemakers additionally were studied by means of subcostal M-mode echocardiography of the right atrial wall. They were programmed on low atrial rate and in VDD mode. Echocardiograms were recorded at every atrial sensitivity setting. The alteration of the time interval between maximum of the atrial contraction and ventricular spike was measured and named as the "atrioventricular SSI.” Average overall SSI's (programming from highest to lowest sensitivity) were 19 ms in ventricular and 12 ms in dual chamber pacemakers. There was no significant difference in sensing shift characteristics among various pacemakers (4 manufacturers, 11 models) used in this study. The SSI duration depends on the endocardial signal waveform and is in inverse proportion to its slew-rate. Contemporary design of sensing circuits does not comply with the clinical demand for timing precision. Sensitivity programming can distort the critical timing of antitachycardia pacemaker as well as it can exert influence on the patient’s rhythm in DDD pacing.

pacing; sensing; intracardiac EGM

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