The risk of atrial fibrillation during right ventricular pacing.

Aims: Right ventricular pacing adversely affects left atrial (LA) structure and function that may trigger atrial fibrillation (AF). This study compares the occurrence of persistent/permanent AF during long-term Hisian area (HA), right ventricular septal (RVS), and right ventricular apex (RVA) pacing in patients with complete/advanced atrioventricular block (AVB).

Methods And Results: We collected retrospective data from 477 consecutive patients who underwent pacemaker implantation for complete/advanced AVB.

Injury to the coronary arteries and related structures by implantation of cardiac implantable electronic devices.

Damage to the coronary arteries and related structures from pacemaker and implantable cardioverter-defibrillator lead implantation is a rarely reported complication that can lead to myocardial infarction and pericardial tamponade that may occur acutely or even years later. We summarize the reported cases of injury to coronary arteries and related structures and review the causes of troponin elevation in the setting of cardiac implantable electronic device implantation.

The changing landscape of cardiac pacing.

A number of trials have shown that irrespective of baseline QRS duration, left ventricular (LV) dysfunction and heart failure are more common in patients with right ventricular (RV) than in those with biventricular (BiV) pacing. By contrast, preliminary results of the BIOPACE trial (follow-up 5.6 years) yielded a disappointing comparison of RV vs.

Atrioventricular block precipitated by isoproterenol.

An isoproterenol infusion was administered during an electrophysiologic study (EPS) in a patient with a history of near syncope, left bundle branch block, and no documented atrioventricular (AV) block. Isoproterenol precipitated classic 2:1 Infra-Hisian AV block most probably proximal to the site of recording a His-Purkinje potential consistent with right bundle branch activity. Paroxysmal AV block also occurred during isoproterenol washout at a different site located distal to the presumed right bundle branch potential.

Understanding the timing cycles of a cardiac resynchronization device designed with left ventricular sensing.

Some devices used for cardiac resynchronization therapy (CRT) can sense from the left ventricular (LV) lead as in Biotronik CRT devices (Biotronik GmbH, Berlin, Germany), whose special LV timing cycles form the basis of this report. LV sensing (LVs) was designed to prevent competitive pacing outside the LV myocardial absolute refractory period. LVs works by inhibiting the release of an LV pacemaker stimulus (LVp) in the vulnerable period of the LV during a programmable period.

Far-field atrial sensing by the left ventricular channel of a biventricular device.

Background: The left ventricular (LV) channel of Biotronik biventricular devices used for cardiac resynchronization therapy (CRT) is designed with the capability of sensing via the LV lead. Therefore a displaced LV lead in a coronary vein could sense far-field atrial signals and interfere with CRT.

Methods: The Biotronik troubleshooting archives containing data of approximately 700 transvenous CRT-D cases (D = defibrillator) were examined for atrial far-field sensing by the LV channel.

The effect of hyperkalaemia on cardiac rhythm devices.

In patients with pacemakers, hyperkalaemia causes three important abnormalities that usually become manifest when the K level exceeds 7 mEq/L: (i) widening of the paced QRS complex from delayed intraventricular conduction velocity, (ii) Increased atrial and ventricular pacing thresholds that may cause failure to capture. In this respect, the atria are more susceptible to loss of capture than the ventricles, and (iii) Increased latency (usually with ventricular pacing) manifested by a greater delay of the interval from the pacemaker stimulus to the onset of depolarization. First-degree ventricular pacemaker exit block may progress to second-degree Wenckebach (type I) exit block characterized by gradual prolongation of the interval from the pacemaker stimulus to the onset of the paced QRS complex ultimately resulting in an ineffectual stimulus.

Will biventricular pacing replace right ventricular pacing for antibradycardia therapy?

Evaluation of: Curtis AB, Worley SJ, Adamson PB, et al; Biventricular versus Right Ventricular Pacing in Heart Failure Patients with Atrioventricular Block (BLOCK HF) Trial Investigators. Biventricular pacing for atrioventricular block and systolic dysfunction. N.

A review of the confirmation algorithm and related timing cycles of St. Jude ICDs.

The confirmation algorithm of implantable cardioverter-defibrillators (ICDs) functioning in the uncommitted mode verifies the presence of a continuing tachyarrhythmia during or following charging of the capacitor. Confirmation is usually applied in relation to the first shock. The details of the normal reconfirmation process of St.

Automatic mode switching of a dual chamber implantable cardioverter-defibrillator induced by a ventricular escape rhythm.

This report describes a form of group beating induced by a St Jude dual chamber ICD which interpreted a ventricular escape rhythm (with retrograde conduction) as premature ventricular complexes (PVC). These pacemaker-defined PVCs activated the atrial pace-PVC algorithm in 2 steps. 1.

Second-degree atrioventricular block revisited.

Type I second-degree atrioventricular (AV) block describes visible, differing, and generally decremental AV conduction. The literature contains numerous differing definitions of second-degree AV block, especially Mobitz type II second-degree AV block. The widespread use of numerous disparate definitions of type II block appears primarily responsible for many of the diagnostic problems surrounding second-degree AV block.

Dissimilar ventricular rhythms: implications for ICD therapy.

Sensing of left ventricular (LV) activity in some devices used for cardiac resynchronization therapy (CRT) was designed primarily to prevent the delivery of an LV stimulus into the LV vulnerable period. Such a sensing function of the LV channel is not universally available in contemporary CRT devices. Recordings of LV electrograms may provide special diagnostic data unavailable solely from the standard right ventricular electrogram and corresponding marker channel.

Functional atrial undersensing associated with switching to a tracking mode of pacing.

We have previously demonstrated that contemporary St. Jude devices (pacemakers and implantable cardioverter-defibrillators [ICDs]; St. Jude Medical, Sylmar, CA, USA) are designed to generate an extended postventricular atrial refractory period (PVARP) of 475 ms at the termination of conventional automatic mode switching (AMS) in response to atrial tachyarrhythmias .