Giuseppe Picciolo

SafeR and escape junctional rhythm: A singular trigger for pacemaker-mediated tachycardia

A 70-year-old man, who previously received a dual chamber pacemaker for paroxysmal AV block (Sorin Symphony DR 2550), was noted on telemetry to have multiple episodes of rapid ventricular pacing at approximately 120bpm. Evaluation of the telemetry strips revealed that all of the rapid ventricular pacing episodes were initiated by brief runs of escape junctional rhythm. Programmed bradycardia parameters were AAI SafeR with lower rate limit of 50bpm.

Resynchronization therapy in heart failure with right bundle branch block: new perspectives

To the Editor: We enjoyed reading the interesting article by Giudici et al. [1], recently published in this Journal, about the effects of right ventricular (RV) septal pacing in patients with right bundle branch block (RBBB). Synchronized RV septal pacing was found to significantly reduce QRS duration with almost normalization of the ECG. Cardiac resynchronization therapy (CRT) by biventricular pacing is recommended, in addition to optimal medical therapy, in selected patients with congestive heart failure (CHF), advanced left ventricular (LV) systolic dysfunction and prolonged QRS interval. Objective of biventricular pacing is to restore atrio-ventricular (A-V), inter-ventricular (V-V) and intra-LV synchrony in order to reduce symptoms and to improve cardiac function and outcomes. The presence of a typical left bundle branch block (LBBB) morphology of the QRS complex is a strong predictor of response to CRT with biventricular pacing, whereas right bundle branch block (RBBB) morphology and non-specific intra-ventricular conduction disturbances are associated with a low rate of response. This holds true especially in patients with isolated RBBB (namely, in absence of left anterior or posterior hemiblock). In this condition, the left bundle branch is preserved and, probably, LV pacing is unnecessary if not self-defeating. As reported in this study [1], a septal positioning of the RV lead, joined to an opportune A-V setting, could turn a dual chamber device into a de facto CRT device. This occurs thanks to an optimal fusion between right ventricular septal stimulation and preserved left bundle branch conduction, leading to a significant narrowing of QRS complex. The results of this initial pilot study are encouraging, as they suggest that this pacing technique in patients with RBBB is feasible and safe. The study, however, did not specifically evaluate patients with CHF, as the population included both patients receiving pacemaker for conventional indications to cardiac pacing and patients receiving implantable cardioverter defibrillator (ICD) for primary or secondary prevention [1]. Some months ago we had reported in this Journal a case of normalization of QRS duration after RV septal pacing in a patient with refractory CHF and RBBB receiving ICD for primary prevention [2]. Also in our case, a significant narrowing of QRS complex (from 180 ms to 100 ms) had been obtained with a dual chamber device, thanks to a fusion

Functional atrial undersensing associated with device algorithm promoting AV conduction

A 58-year-old woman received a dual chamber pacemaker (Medtronic) for sick sinus syndrome. Given intact AV conduction the Managed Ventricular Pacing mode algorithm (MVP) was programmed. The day after, she suffered from palpitations. Her ECG showed a possible loss of atrial capture accompanied by atrial undersensing. Telemetry-supported pacemaker control confirmed the loss of capture. Undersensing of atrial signal was functional, related to long atrial refractory period in MVP mode algorithm. Device algorithms could induce false suspicions. Awareness about the different pacing algorithms can be useful in order to avoid erroneous interpretations and to correct potential malfunctioning.

V > A: When the paradigm fails!

AFilipino45-year-oldmanwith a history of coronary heart disease and congestive heart failure (CHF), who previously received a biventricular cardioverter defibrillator (Quadra AssuraMP 3371-40C St. JudeMedical, Abbott, St. Paul, MN, USA), was admitted for palpitations. He was receiving optimalmedical therapy for CHF (namely loop diuretic, betablocker, angiotensin-converting-enzyme [ACE]-inhibitor, aldosterone antagonist, and ivabradine) besides aspirin. The electrocardiogram (ECG) showed wide QRS tachycardia at 160 beats per minute (bpm) with a singular bigeminal rhythm (see Fig. 1). The patient was hemodynamically stable (arterial bloodpressure [ABP] 130/80mmHg). ContinuousECGmonitoringandaperipheral venousaccesswereobtained. QRS complexes had a typical right bundle branch block with left anterior hemiblock morphology, suggesting supraventricular tachycardia (SVT) with aberrancy. Analysis of lead V1 (where P wave was better observable) was not conclusive for atrial flutter/atrial tachycardia diagnosis or atrio-ventricular (AV) dissociation. A clear P wave was seen after the second QRS complex of any couple. Other atrial activity waves could have been partially hidden by wide QRS complexes. Previous ECGs were not immediately available. Telemetry-supported pacemaker control was performed in order to facilitate a diagnosis. It showed 3 arrhythmic episodes in VT2 zone, each one interrupted after single burst of antitachycardia pacing therapy (ATP; see Fig. 2). Surprisingly, ventricular rate was double than atrial activity, suggesting ventricular tachycardia (VT) diagnosis. Current EGMs were identical. What is themechanism of this bigeminal tachycardia?