Clinical utility of telemetered intracardiac electrograms in diagnosing a design dependent lead malfunction

Inhibition of pacemakers due to false signals from malfunctioning pacing leads has been previously reported. Three cases are reported in which inappropriate pauses were observed shortly following implantation. In all three cases, active fixation leads with an electronically active screw and ring tip electrode were used. All leads were manufactured by Oscor Medical, St. Petersburg, Florida. In case one, models PY-61 (ventricle) and PY-51 (atrium) were used. In case two, models PY-61 were used in the ventricle and the atrium. In case three, models PY-52 were used both in the atrium and ventricle. Thresholds at the time of implantation were acceptable. In cases one and two, inappropriate pauses were noted following paced ventricular beats. In case three, inappropriate inhibition of the ventricular output was noted intermittently after some of the paced atrial beats. Spurious signals were identified as the cause of the apparent oversensing problem by using electrocardiograms with annotated telemetry information and noninvasively telemetered intracardiac electrograms. The amplitude of the spurious signals varied between 2 and 14 mV. In all cases, the problems resolved with time. A mechanism for the generation of false transients is proposed and the value of telemetered intracardiac electrograms is discussed.