Endless‐Loop Tachycardias: Description and First Clinical Results of a New Fully Automatic Protection Algorithm

The autointrinsic conduction search (AICS) option, featured on some DDD pacemakers, performs periodic assessments of atrioventricular (AV) conduction capability during a single beat AV delay extension. Demonstration of ventricular conduction during the prolonged AV delay, permits ongoing AV delay extension if the patient's intrinsic conduction is preferred to ventricular pacing. A case is presented where the wide separation of atrial and ventricular pacing during the conduction search permitted retrograde ventriculoatrial conduction, precipitating pacemaker mediated tachycardia (PMT) on seven occasions in one patient. Two onset patterns are reported, both attributable to the AICS option. Recommendations for prevention strategies are made.

Section: Discussionmentioning

confidence: 99%

Pacemaker Mediated Tachycardia as a Complication of the Autointrinsic Conduction Search Function

Dennis

Sparks

2004

“…The method more often used for preventing endless‐loop tachycardia is the programming of a long PVARP. Automated interventions to terminate PMT are now featured on all dual‐chamber devices, based largely on automatic PVARP extensions after several beats with retrograde conduction (average 8) 1,6,7 . However, this will limit the patient's upper ventricular rate, which may be deleterious to cardiac function or cause symptoms.…”

Section: Discussionmentioning

confidence: 99%

“…Automated interventions to ABLATION IN PACEMAKER-MEDIATED TACHYCARDIA terminate PMT are now featured on all dualchamber devices, based largely on automatic PVARP extensions after several beats with retrograde conduction (average 8). 1,6,7 However, this will limit the patient's upper ventricular rate, which may be deleterious to cardiac function or cause symptoms. When these algorithms are not adequate to prevent or terminate the PMT or pacemaker syndrome is present, the ablation of the node AV is necessary.…”

Section: Discussionmentioning

confidence: 99%

Catheter Ablation of Accessory Pathway in the Treatment of Pacemaker‐Mediated Tachycardia

Robledo-Nolasco

Ortiz-Avalos

Rodríguez-Diez

et al. 2011

Pacemaker-mediated tachycardia (PMT) remains a clinical problem in patients with dual-chamber pacemaker despite technological advances. The onset mechanism of this tachycardia is sensing of retrograde atrial activation after ventricular stimulation. Repeated retrograde conduction perpetuates tachycardia. Postventricular atrial refractory period prolongation has been used for prevention of PMT, but this is not the solution in all cases. We present a case with PMT where the retrograde limb is a left accessory pathway, which is treated with radiofrequency ablation successfully.

“…The St. Jude algorithm uses modulation of the AV (PV) delay for one cardiac cycle regardless of the pacing rate to detect PMT 1–3 . The pacemaker identifies PMT if the same ventricular paced event (V) gives rise to a stable unchanged ventricular pacing (VP) interval because in PMT the retrograde ventriculoatrial conduction almost always remains constant.…”

Section: Discussionmentioning

confidence: 99%

Pacemaker Tachycardia: Is it Pacemaker‐Mediated Tachycardia or Sinus Tachycardia?

Barold

Leonelli

Khan

et al. 2007

A 38-year-old woman received a transvenous St. Jude Atlas + HF V-340 biventricular implantable cardioverter defibrillator (ICD; Sylmar, CA, USA) for a nonischemic dilated cardiomyopathy associated with drug-refractory congestive heart failure, left bundle branch block, and a left ventricular ejection fraction of 20%. About a year later she was referred to our center for the first time after sustaining 2 shocks related to supraventricular tachycardia at a rate of 210 bpm, which was documented in stored electrograms. There was no evidence of congestive heart failure. Upon interrogation of the device, we retrieved only one memorized episode labeled as a pacemaker-mediated tachycardia (PMT). The programmed parameters were as follows: Base rate = 70 ppm, maximum tracking rate = 140 ppm, Atrial pacing-ventricular pacing/atrial sensing-ventricular pacing (AV/PV) delay = 120/90 ms (A = atrial paced event, V = ventricular paced event, P = atrial sensed event), PMT option = A Pace on PMT (detection rate = 100 bpm), and a rate-responsive postventricular atrial refractory period. Ventricular fibrillation detection interval = 280 ms for 12 intervals but ventricular tachycardia was turned off. Testing the device revealed normal pacing, sensing, high and low voltage impedances, and battery function. Did the device make the correct diagnosis of PMT in the stored electrograms shown in Fig. 1? DiscussionThe St. Jude algorithm uses modulation of the AV (PV) delay for one cardiac cycle regardless of the pacing rate to detect PMT. 1-3 The pacemaker identifies PMT if the same ventricular paced event (V) gives rise to a stable unchanged ventricular pacing (VP) interval because in PMT the retrograde ventriculoatrial conduction almost always remains constant. In a supraventricular tachycardia (SVT) or sinus tachycardia the change of the AV delay will alter the VP interval to the same degree. When the atrial rate becomes equal to or exceeds the programmed PMT detection rate for 8 consec-Address for reprints: S. utive PV cycles with VP variation not greater than 16 ms, the device modifies the PV interval by 31 ms. If the previous PV interval was ≥100 ms, the PV interval is shortened by 31 ms. If the previous PV was <100 ms, the PV is lengthened by 31 ms. Then, the device compares the new or modified VP interval with the average VP interval before the single altered PV interval AV delay. If the VP interval remains within 16 ms of the average VP interval, the device makes the diagnosis of PMT. When the PMT algorithm is set to A (Atrial) Pace on PMT, the pulse generator withholds a ventricular output and releases an atrial output pulse 330 ms after the detected P wave in an attempt to terminate the PMT. The atrial pulse is inhibited if a P wave or an R wave is detected during the 330 ms window before the scheduled atrial stimulus.In Fig. 1 the VP intervals can be calculated from the annotated data showing atrial and ventricular intervals. The VP interval becomes equal to the interventricular (VV) interval minus the AV delay (PV interval), whi...