Pacemaker-mediated Tachycardia Research Articles

Endless loop tachycardia among patients with devices having advanced preventive algorithms: A case series and brief review.

Endless loop tachycardia (ELT) is the commonest pacemaker mediated tachycardia (PMT) encountered among patients with cardiac implantable electronic devices (CIEDs). Despite being enabled with various preventive algorithms, we encountered several cases having recurrent, long, and symptomatic ELT. We retrospectively analyzed consecutive device checkups at device clinic at a single center of eastern India between January 2019 to March 2023. There were 20 cases of confirmed and sustained ELT among 4520 device checks. Although mostly benign, in two cases ELT led to clinical worsening in patients having left ventricular (LV) systolic dysfunction. Even with good ventricular function, ELT resulted in improper atrioventricular (AV) synchrony leading to disabling symptom in one case. The differentiation of ELT from sinus tachycardia and atrial tachycardia (AT) was not always easy. Magnet application is certainly useful to differentiate. The situations that provoked ELT in this study were-long AV delays, VIP (ventricular intrinsic preferences)/MVP (managed ventricular pacing), atrial non-capture, atrial under/over sensing, premature ventricular contractions (PVCs)/couplets, premature atrial contractions (PAC) and slower ventriculo-atrial (VA) conduction. Rate responsive shortening of post-ventricular atrial refractory period (PVARP) also promoted its occurrence and hindered troubleshooting. When ELT occurred despite post-PVC extension of PVARP, lowering the atrial sensitivity, switching to bipolar sensing and manual setting of longer PVARP after measuring VA conduction time were useful. "Rate responsive PVARP" had to be turned off in a few cases to prevent ELT. On the contrary, an over aggressive prolongation of PVARP led to repetitive non-reentrant ventriculo-atrial synchrony (RNRVAS) in two cases. Checking VA conduction during implantation and noninvasive program stimulation (NIPS) during follow up were useful to check the tendency for ELT. Clinically significant ELT is rare but not uncommon among devices having in-built preventive algorithms. Manual adjustments are often useful to troubleshoot the same.

Ventricular Pacing in Pacemaker Bigeminy to Rule in/out Truncated Pacemaker-mediated Tachycardia

Pacemaker bigeminy is not an uncommon electrocardiographic finding in device clinics. However, such a pattern mandates the differentiation of important possible diagnostic considerations such as premature atrial contractions, oversensing the T wave or the QRS complex, dual AV nodal physiology, and retrograde atrial depolarization. We present a case of pacemaker bigeminy where ventricular pacing was used to exclude the truncated form of pacemaker-mediated tachycardia and reach a diagnosis of atrial bigeminy, which was crucial from the management’s perspective.

Pacemaker-Mediated Tachycardia Interpolated Into Ventricular Tachycardia

In a 77-year-old patient with a history of inferior myocardial infarction and dual-chamber pacemaker (Effecta DR, Biotronik) implanted for carotid sinus syndrome, a routine Holter electrocardiogram recorded 3 consecutive tachycardias: irregular monomorphic ventricular tachycardia (VT), pacemaker-mediated tachycardia (PMT), and reoccurred VT (re-VT) of the same morphology as the initial one, but regular and faster than the PMT (Fig. 1).The pacemaker settings were as follows: DDD mode; pacing rate, 50 to 130 bpm; programmed atrioventricular delay, paced 145 ms and sensed 105 ms; and postventricular atrial refractory period (PVARP), 250 ms and 400 ms following premature ventricular contraction.What was the most likely mechanism of this arrhythmia?B) PMT was triggered by atrial premature beat and terminated by the re-VT (Fig. 2) Concerning the mode of the PMT initiation, the VT could not trigger PMT because its retrograde P wave (in Fig. 2, stars denote retrograde P waves; those of the VT and re-VT are marked below and those of the PMT above the middle electrocardiographic channel) occurred during the PVARP (gray horizontal marks in the ladder diagram). Given that the interrogation showed no pacemaker malfunctions and that the electrocardiogram showed no artifacts, an atrial ectopic beat (with isoelectric P wave) is the only likely trigger for PMT.Concerning the mode of PMT termination, the episode was too short to activate the device's PMT termination algorithm. Furthermore, the retrograde P wave from the last PMT beat, which appeared after 344 ms, indicates that retrograde conduction has been prolonged, but without occurrence of a block that would have stopped the PMT. Thus, the re-VT is what terminated the PMT by the first impulse following fusion (f2 in Fig. 2), which depolarized ventricles before the possible onset of the next paced beat. Retrograde conduction prolongation (by 24 ms) and programmed atrioventricular delay prolongation (by 50 ms, for Biotronik's PMT status confirmation) during the last PMT cycle provided a time for the onset of the re-VT and thus indirectly participated in the PMT termination.Based on the constant cycle length (382 ms) of the re-VT during the prolongation of ventriculoatrial conduction (from 170 to 240 ms), the re-VT was most probably microreentrant. Different retrograde conduction times of the VT (160 ms) and PMT (315 ms) might suggest the existence of a dual retrograde conduction with separate pathways for each of the 2 tachycardias, but any evidence for such speculation is lacking. In any case, this case illustrates the complexity of possible interactions between spontaneous and device-mediated arrhythmias.

B-PO05-211 PROGRAMMING CHALLENGES DURING LEFT VENTRICULAR PACING. A CASE OF PACEMAKER-MEDIATED TACHYCARDIA

Multichamber pacing may be associated with complex interactions between pacing timing cycles. Review of a case of pacemaker mediated tachycardia (PMT) during LV pacing. Data was collected by retrospective review. A patient with a history of coronary artery disease and bypass surgery, heart failure and primary prophylaxis dual chamber defibrillator (ICD) underwent upgrade to a biventricular ICD (Boston Scientific Vigilant X4 G247) due to new left bundle branch block and heart failure symptoms. Postoperative programming was identical (DDDR 50/130/130 bpm; PVARP 240-280 ms) except for shortened AV delay with simultaneous RV/LV pacing. During an admission to an outside hospital, AV delay was shortened (SAV: 100 ms, PAV 150 ms) and pacing mode was changed to LV only. In follow-up, numerous PMT episodes were noted in the device memory (Panel A) and also during device interrogation but only with LV-only pacing. Retrograde P wave during LV pacing fell outside the programmed PVARP because retrograde left bundle branch block caused transseptal retrograde conduction via the right bundle branch with delay in LV to RA interval. Timing from RV apex to RA (Panel B, red arrow, 240 ms) was the same during RV pacing and during LV pacing (panel C) but because PVARP is initiated with the first paced ventricular chamber, the V to A time prolonged with LV-only pacing (Panel C, blue arrow, 420 ms) beyond PVARP. Programming very long PVARP limits upper tracking rate so in this case we switched to biventricular pacing which shortened the QRS duration and also eliminated PMT episodes. In CRT devices, PVARP should be reassessed when LV only pacing is programmed.

A rare case of pacemaker mediated tachycardia caused by intrinsic conduction search function of a dual chamber pacemaker

Pacemaker-mediated tachycardia (PMT) is a well-described cause of tachyarrhythmia in patients with dual chamber pacemakers (Barold, 1991 [1]). PMT is usually caused by common triggers including premature ventricular or atrial complexes (Alasti et al., 2018 [2]). However, PMT can also be triggered by other uncommon mechanisms. Intrinsic conduction search function is a feature available in some dual chamber permanent pacemakers that periodically looks for intrinsic conduction by gradually prolonging the preprogrammed AV delay in an attempt to minimize ventricular pacing (Calvi et al., 2017; Pakarinen and Toivonen, 2013 [3,4]). Here, we report a rare case of PMT triggered by intrinsic conduction search function.

PACEMAKER-MEDIATED TACHYCARDIA UTILIZING AN ACCESSORY PATHWAY

Pacemaker-mediated tachycardia (PMT) is common in patients with dual chamber pacemakers (DCPM). Endless loop tachycardia (ELT) is a type of PMT that is characterized by P-synchronous ventricular pacing, whereby a retrograde P wave occurs outside of the programmed PVARP and is sequentially tracked.

Complete Atrioventricular Block with Intact Retrograde Conduction in Cardiac Rhythm Management Devices: Implications of the Phenomenon.

Intact retrograde ventriculoatrial (VA) conduction in the presence of complete atrioventricular (AV) heart block has been well-documented in the past. We sought to describe the prevalence and clinical significance of intact VA conduction accompanied by complete antegrade AV block in patients with implanted cardiac rhythm management (CRM) devices. During routine follow-up of CRM devices in our device clinic, 42 patients were found to be in a state of complete heart block. All patients presented in sinus rhythm. The patients’ underlying rhythms were tested with the inhibition of pacing and documented AV dissociation. Subsequently, retrograde VA conduction was tested with ventricular pacing. In the 42 patients with complete heart block as the underlying rhythm, five patients demonstrated retrograde VA conduction. In conclusion, the prevalence of intact of VA conduction was 11.9% in our study. The implications of this phenomenon can have noteworthy clinical significance. The occurrence of pacemaker-mediated tachycardia and repetitive nonreentrant VA synchrony are discussed herein. All patients, even those with a device indication of complete heart block, should be tested for retrograde conduction at implantation and during routine follow-up.

TREATMENT OF PACEMAKER MEDIATED TACHYCARDIA VIA ABLATION OF A CONCEALED ACCESSORY PATHWAY IN A PATIENT WITH CONGENITAL COMPLETE HEART BLOCK

Pacemaker mediated tachycardia (PMT) in a young patient with congenital complete heart block (CHB) presents both a diagnostic and therapeutic challenge with limited device-based programming options. A 22 year old athletic male with past medical history of congenital CHB and epicardial dual chamber

216-35: Performance of the RYTHMIQ(TM) algorithm to minimize right ventricular pacing: a multicenter study

Background: In Boston Scientific dual-chamber devices, the RYTHMIQ(TM) algorithm aims to minimize RV pacing. We evaluated its performance by determining 1) the appropriateness of the switch from the AAI(R) with backup VVI pacing to the DDD(R) mode in case of suspected loss of AV conduction and 2) the rate of recorded pacemaker mediated tachycardia (PMT) when AV hysteresis searches for restored AV conduction. Conclusion: The RYTHMIQ algorithm shows: 1) high rate of inappropriate switch (mostly PVCs) and 2) high rate of induction of PMT. This may have clinical implications in terms of selection of the patients and may suggest required changes in the algorithm architecture.

Accuracy of the pacemaker-mediated tachycardia algorithm in Boston Scientific devices

IntroductionThe incidence of pacemaker-mediated tachycardia (PMT) varies as a function of patient characteristics, device programming and algorithm specificities. We investigated the efficacy of the Boston Scientific algorithm by reviewing PMT episodes in a large device population. MethodsIn this multicenter study, we included 328 patients implanted with a Boston Scientific device: 157 non-dependent patients with RYTHMIQ™ activated (RYTHMIQ group), 76 patients with permanent AV-conduction disorder (AV-block group) and 95 Cardiac Resynchronization Therapy patients (CRT group). For each patient, we reviewed the last 10 remote monitoring-transmitted EGMs diagnosed as PMT. ResultsWe analyzed 784 PMT episodes across 118 patients. In the RYTHMIQ group, the diagnosis of PMT was correct in most episodes (80%) of which 69% was directly related to the prolongation of the AV-delay associated with the RYTHMIQ algorithm. The usual triggers for PMT were also observed (PVC 16%, PAC 9%). The remainder of the episodes (20%) in RYTHMIQ patients and most episodes of AV-block (66%) and CRT patients (74%) were incorrectly diagnosed as PMT during sinus tachycardia at the maximal tracking rate. The inappropriate intervention of the algorithm during exercise causes non-conducted P-waves, loss of CRT (sustained in six patients) and may have been pro-arrhythmogenic in one patient (induction of ventricular tachycardia). ConclusionAlgorithms to minimize ventricular pacing can occasionally have unintended consequences such as PMT. The PMT algorithm in Boston Scientific devices is associated with a high rate of incorrect PMT diagnosis during exercise resulting in inappropriate therapy with non-conducted P-waves, loss of CRT and limited risk of pro-arrhythmic events.

Validation of device algorithm to differentiate pacemaker-mediated tachycardia from tachycardia due to atrial tracking

Current cardiac devices cannot always differentiate between pacemaker-mediated tachycardia (PMT) and tracking of sinus or atrial tachycardia. We previously derived a novel algorithm for distinguishing the 2 mechanisms based on the specific termination response to postventricular atrial refractory period extension, atrial rates, and changes in atrial electrogram morphology. The purpose of this study was to evaluate how this algorithm would have performed in a clinical setting based on previously recorded PMT events. We applied our algorithm to a database of 122 de-identified stored electrograms that were classified as PMT by 43 remotely monitored devices. Of the 122 events stored as "PMT," 3 episodes were excluded because the device recording was consistent with atrial fibrillation. Of the remaining 119 episodes, our algorithm was able to correctly reclassify 92 events (77%) as tracking of sinus or atrial tachycardia rather than true PMT. The VAV response following postventricular atrial refractory period extension, which is specific to tracking of atrial or sinus tachycardia, was seen in 72% of these cases. Changes in atrial rate and atrial electrogram morphology were able to reclassify the remainder of episodes. Finally, we observed that 12 of 83 episodes (14%) misclassified as PMT in cardiac resynchronization devices resulted in loss of cardiac biventricular pacing. Applying a novel diagnostic algorithm to current cardiac devices improves the proper diagnosis of true PMT rather than tracking of atrial or sinus tachycardia. Enhanced accuracy of diagnosis reduces the likelihood of inappropriate clinical decisions.

Tracking preference as unusual trigger of pacemaker-mediated tachycardia in a resynchronization device

A 59-year-old woman with a history of congestive heart failure, who previously received a biventricular cardioverter–defibrillator was admitted with dyspnea and peripheral edema. She was noted on telemetry to have multiple self-terminated episodes of rapid ventricular pacing, consistent with pacemaker-mediated tachycardia. All episodes started after three consecutive ventricular extrasystoles. “Tracking preference” algorithm, designed to maintain atrial-tracked biventricular pacing in CRT devices, resulted turned on. It affected minimum PVARP and resulted the trigger for pacemaker mediated tachycardia.

Performance of a specific algorithm to minimize right ventricular pacing: A multicenter study

In Boston Scientific dual-chamber devices, the RYTHMIQ algorithm aims to minimize right ventricular pacing. We evaluated the performance of this algorithm determining (1) the appropriateness of the switch from the AAI(R) mode with backup VVI pacing to the DDD(R) mode in case of suspected loss of atrioventricular (AV) conduction and (2) the rate of recorded pacemaker-mediated tachycardia (PMT) when AV hysteresis searches for restored AV conduction. In this multicenter study, we included 157 patients with a Boston Scientific dual-chamber device (40 pacemakers and 117 implantable cardioverter-defibrillators) without permanent AV conduction disorder and with the RYTHMIQ algorithm activated. We reviewed the last 10 remote monitoring-transmitted RYTHMIQ and PMT episodes. We analyzed 1266 episodes of switch in 142 patients (90%): 207 (16%) were appropriate and corresponded to loss of AV conduction, and 1059 (84%) were inappropriate, of which 701 (66%) were related to compensatory pause (premature atrial contraction, 7%; premature ventricular contraction, 597 (56%); or both, 27 (3%)) or to a premature ventricular contraction falling in the post-atrial pacing ventricular refractory period interval (219, 21%) and 94 (10%) were related to pacemaker dysfunction. One hundred fifty-four PMT episodes were diagnosed in 27 patients (17%). In 85 (69%) of correctly diagnosed episodes, the onset of PMT was directly related to the algorithm-related prolongation of the AV delay, promoting AV dissociation and retrograde conduction. This study highlights some of the limitations of the RYTHMIQ algorithm: high rate of inappropriate switch and high rate of induction of PMT. This may have clinical implications in terms of selection of patients and may suggest required changes in the algorithm architecture.

Pacemaker-Mediated Tachycardia: Manufacturer Specifics and Spectrum of Cases.

Pacemaker-mediated tachycardia (PMT) is the term used to describe a repetitive sequence of sensed retrograde P waves followed by ventricular pacing at or below the maximum tracking rate. The following events can promote atrioventricular (AV) dissociation, retrograde conduction, and the onset of PMT: ventricular or atrial extrasystole, an excessively long programmed AV delay, external interference or myopotentials sensed by the atrial channel, atrial sensing or pacing failure, the absence of postventricular atrial refractory period extension after removal of a magnet, and VDD pacing at a higher rate than sinus rate. In contemporary devices, each manufacturer has a proprietary algorithm to detect and terminate PMT. Because of the increase in the number and complexity of the pacing algorithms and because of manufacturer-driven differences, a basic understanding of these new algorithms is important for patient care. We review here the main elements of the physiopathology of this type of tachycardia, describe the specific characteristics of the different manufacturers, and present representative clinical cases.

Shortness of breath in a patient with complete heart block and permanent pacemaker: A case of effective pacemaker reprogramming

An 82-year-old frail woman with a prior history of hypertension, complete heart block, and dual permanent pacemaker (Sensia DR SEDR01, Medtronic Inc., Minneapolis, MN) presented to pacemaker clinic with symptoms of shortness of breath (SOB), dizziness, and “low pulse rate”. Pacemaker interrogation showed underlying normal sinus rhythm, sinus rate of around 74 beats/ min with atrial sensed events, and ventricular paced rhythm with frequent symptomatic premature ventricular complexes (PVC). Pacemaker parameters were DDD, lower rate limit (LRL) of 60 beats/min, and maximum tracking rate of 120 beats/min, along with paced/sensed AV delay of 300/250 ms. Also noted was high pacing threshold of 3.5 V at 1 ms in the atrial lead with normal sensing parameters. In view of these, the pacemaker mode was reprogrammed to VDD mode and the patient was given betablocker therapy for frequent PVCs. She presented to arrhythmia clinic a few weeks later because of worsening SOB, light-headedness, and transient ischemic attacklike symptoms. Electrocardiography (ECG) performed in the clinic showed ventricular paced rhythmwith retrograde P waves (Fig. 1). What was the underlying arrhythmia mechanism? What treatment options are available? 2. Discussion

Simulation of Intraoperative Pacemaker Failure

Simulation of Intraoperative Pacemaker Failure

Closed-loop verification of medical devices with model abstraction and refinement

The design and implementation of software for medical devices is challenging due to the closed-loop interaction with the patient, which is a stochastic physical environment. The safety-critical nature and the lack of existing industry standards for verification make this an ideal domain for exploring applications of formal modeling and closed-loop analysis. The biggest challenge is that the environment model(s) have to be both complex enough to express the physiological requirements and general enough to cover all possible inputs to the device. In this effort, we use a dual chamber implantable pacemaker as a case study to demonstrate verification of software specifications of medical devices as timed-automata models in UPPAAL. The pacemaker model is based on the specifications and algorithm descriptions from Boston Scientific. The heart is modeled using timed automata based on the physiology of heart. The model is gradually abstracted with timed simulation to preserve properties. A manual Counter-Example-Guided Abstraction and Refinement (CEGAR) framework has been adapted to refine the heart model when spurious counter-examples are found. To demonstrate the closed-loop nature of the problem and heart model refinement, we investigated two clinical cases of Pacemaker Mediated Tachycardia and verified their corresponding correction algorithms in the pacemaker. Along with our tools for code generation from UPPAAL models, this effort enables model-driven design and certification of software for medical devices.

Taquicardias de complejo QRS ancho precedidas de espiga de marcapasos

The differential diagnosis and therapeutic management of wide QRS tachycardia preceded by pacemaker spike is presented. The pacemaker-mediated tachycardia, tachycardia fibrillo-flutter in patients with pacemakers, and runaway pacemakers, have a similar surface electrocardiogram, but respond to different therapeutic measures. The tachycardia response to the application of a magnet over the pacemaker could help in the differential diagnosis, and in some cases will be therapeutic, as in the case of a tachycardia-mediated pacemaker. Although these conditions are diagnosed and treated in hospitals with catheterization laboratories using the application programmer over the pacemaker, patients presenting in primary care clinic and emergency forced us to make a diagnosis and treat the haemodynamically unstable patient prior to referral.

Perioperative Management of Cardiovascular Implantable Electronic Devices

1titled “Perioperative Pacemaker-Mediated Tachycardia in the Patient with a Dual Chamber Implantable Cardioverter-Defibrillator.” The authors describe the management of a patient who undergoes hip surgery with ischemic cardiomyopathy and an implantable cardioverter-defibrillator (ICD) inserted for primary prevention of sudden cardiac death. This case report is an excellent demonstration of classic pacemakermediated tachycardia (PMT) in a patient with an ICD. PMT is seen in patients with a dual chamber pacemaker, whose conduction is anterograde via the pacemaker with retrograde conduction via the atrioventricular node where the activation of the atria is outside the programmed postventricular atrial refractory period (PVARP). As in this case, a premature ventricular contraction is conducted in a retrograde fashion and is improperly interpreted by the atrial channel of the pacemaker as a native atrial impulse, which initiates a paced ventricular beat. The authors correctly emphasize the difference in acute management of PMT depending on whether the device is a pacemaker or an ICD. If the device is a pacemaker, a magnet applied to the generator will result in asynchronous pacing of the heart (DOO), thus eliminating the atrial tracking and timing of a ventricular impulse. An ICD cannot be placed in asynchronous mode by applying a magnet; its pacemaker (bradycardia therapy) can only be altered by using a manufacturer-specific programmer. Extending the PVARP interval such that the atrial channel does not sense any retrograde conduction from the ventricles will also terminate a PMT. Many of the current cardiac implantable electronic devices (CIEDs) have a specialized algorithm that allows the PVARP to be automatically extended in the presence of premature ventricular contraction.

Perioperative Pacemaker-Mediated Tachycardia in the Patient with a Dual Chamber Implantable Cardioverter-Defibrillator

Patients with cardiac implantable electronic devices are at additional risk for arrhythmias while undergoing surgical procedures. In this case report, we present a patient with a dual chamber implantable cardioverter-defibrillator who developed intraoperative pacemaker-mediated tachycardia causing significant hemodynamic instability. Management of this arrhythmia can be particularly challenging, because standard application of a magnet does not affect the pacing functions of an implantable cardioverter-defibrillator. Awareness by the anesthesiologist and timely coordination with the cardiac electrophysiology team helped to optimize care for this patient.