Apparent malfunction of demand pacemakers due to spurious potentials generated by contact between two endocardial electrodes

Extraction of sterile leads is the preferred approach rather than implanting a new lead: the con perspective

Lead malfunction is a common problem in implantable cardiac device patients and is expected to increase with the aging of leads. There is a weak indication for extraction of superfluous leads with the potential for cardiac implantable electronic device interference and abandoned or redundant leads; much remains to be learned from clinical practice. Lead extraction, although safe in experienced hands, remains a high-risk procedure, especially in lower-volume centers and/or when performed by lower-volume operators. Therefore, a strategy of abandoning nonfunctioning leads is reasonable, and lead extractions should be reserved for cases with system infection or high lead burden.

Pacemaker inhibition due to anodal ring electrode contact

A 79-year-old patient with a permanent DDD pacemaker due to a complete AV block and severe bradycardia was seen with complaints of syncope. A surface ECG rhythm strip verified the loss of ventricular output with 6-second periods of asystole. Subsequent investigation using the pacemaker's annotated event markers and multiple polarity intracardiac electrograms indicated spurious signals arising from the anodal ring. On fluoroscopic examination intermittent contact was observed between the anodal ring of the pacing lead and the ring electrode of an abandoned lead. Reprogramming of the pulse generator's ventricular channel to the unipolar sensing configuration corrected the problem.

Benefits of intracardiac electrograms and programmable sensing polarity in preventing pacemaker inhibition due to spurious screw-in lead signals

False inhibition of ventricular output due to spurious signals from a bipolar Oscor Medical lead (PY58BV) is reported following implantation of a Pacesetter Synchrony DDDR 2020T. Telemetered bipolar and distal unipolar intracardiac electrograms revealed 20 mV spurious signals coming from the distal screw-in electrode. Reprogramming the sensing channel to unipolar ring prevented inhibition of pacemaker output.

Oversensing from electrode 'chatter' in a bipolar pacing lead: a case report

An 81-year-old man was treated for high degree AV block and syncope with an AV universal (DDD) pacemaker. Bipolar active fixation atrial and ventricular leads were used. Intermittent oversensing from the ventricular lead was detected on Holter monitoring following implantation. This resulted in inappropriate inhibition of ventricular pacing. Ventricular electrogram showed spurious signals between 5 mV and 15 mV in magnitude coincident with ventricular lead inhibition. Treatment consisted of reprogramming the device to the VVT mode. Six weeks after implantation normal pacemaker function in the DDD mode was demonstrated on Holter monitoring and inappropriate pacer inhibition could not be demonstrated. We postulate that electrode 'chatter' between the cathodal ring electrode and the helix of the ventricular lead resulted in artifactual potentials sufficient to inhibit pacing. We hypothesize that fibrosis and fixation of the ventricular lead tip over a period of weeks eliminated these electromechanical artifacts and resulted in the oversensing problem being self-limited. Physicians should be aware of electrode 'chatter' as a cause of pacemaker oversensing.

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.

An unusual complication of the unremoved unwanted pacing wire

A case of external jugular vein thrombosis is described. This occurred following failure to remove an unwanted pacing wire by sustained traction and its subsequent migration from the subclavian vein into the external jugular vein.