Electrogram characteristics in postinfarction ventricular tachycardia: effect of infarct age.

Objectives: The purpose of this study was to correlate infarct age with characteristics of the endocardial electrograms (EGM) obtained in patients undergoing mapping procedures for postinfarction ventricular tachycardia (VT).

Background: Experimental studies have demonstrated that infarct age influences EGM duration in the subepicardial left ventricle (LV). The relationship between infarct age and endocardial EGM characteristics has not been investigated in patients with postinfarction VT.

Topographic analysis of the coronary sinus and major cardiac veins by computed tomography.

Background: The coronary sinus (CS) and its branches may play a role in the genesis of various arrhythmias. Applications of radiofrequency energy within the CS may be necessary. Atrio-esophageal fistula has been recognized as a complication of ablation along the posterior left atrial wall.

Mechanical interruption of postinfarction ventricular tachycardia as a guide for catheter ablation.

Background: Mechanical trauma has been described as a helpful guide for ablation of atrial tachycardias and accessory pathways. In postinfarction ventricular tachycardia (VT), the reentrant circuit is partly endocardial and therefore may be susceptible to catheter trauma.

Objectives: The purpose of this study was to determine the prevalence and significance of VT termination resulting from catheter trauma.

Catheter ablation of atypical atrial flutter and atrial tachycardia within the coronary sinus after left atrial ablation for atrial fibrillation.

Objectives: The goal of this study was to describe the prevalence and ablation of coronary sinus (CS) arrhythmias after left atrial ablation for atrial fibrillation (AF).

Background: The CS has been implicated in a variety of supraventricular arrhythmias.

Methods: Thirty-eight patients underwent mapping and ablation of atypical flutter that developed during (n = 5) or after (n = 33) ablation for AF.

Mechanism of atrial flutter occurring late after orthotopic heart transplantation with atrio-atrial anastomosis.

Objective: We sought to better define the electrophysiologic mechanism of atrial flutter in patients after heart transplantation.

Background: Atrial flutter is a recognized problem in the post-cardiac transplant population. The electrophysiologic basis of atrial flutter in this patient population is not completely understood.

Effects of left atrial ablation of atrial fibrillation on size of the left atrium and pulmonary veins.

Objectives: The purpose of this study was to determine the effect of left atrial circumferential ablation on the size of the left atrium and pulmonary veins (PVs).

Background: The long-term effects of left atrial circumferential ablation on left atrial and PV size and anatomy have not been analyzed in quantitative fashion.

Methods: PV and left atrial sizes were analyzed in 41 consecutive patients (mean age 54 +/- 12 years) with paroxysmal (n = 25) or chronic (n = 16) atrial fibrillation.

Catheter ablation guided by termination of postinfarction ventricular tachycardia by pacing with nonglobal capture.

Objectives: We prospectively investigated the prevalence and value of this criterion for identifying a target site for ablation in patients with postinfarction ventricular tachycardia (VT).

Background: Termination of postinfarction VT by pacing with nonglobal capture identifies a critical component of the reentrant circuit.

Methods: In a consecutive series of 34 patients with prior infarction (age 67 +/- 10 years, ejection fraction 0.

Mechanisms of recurrent atrial fibrillation after pulmonary vein isolation by segmental ostial ablation.

Objectives: The aim of this study was to determine the mechanisms responsible for recurrent atrial fibrillation (AF) after pulmonary vein isolation (PV) by segmental ostial ablation.

Background: Recovery of conduction into a previously isolated PV is a common observation when there is recurrent AF soon after segmental ostial ablation. However, the mechanisms of recurrent AF have been unclear.

Prevalence, mechanisms, and clinical significance of macroreentrant atrial tachycardia during and following left atrial ablation for atrial fibrillation.

Objectives: The purpose of this study was to determine the prevalence and clinical significance of macroreentrant atrial tachycardia (AT) after left atrial (LA) circumferential ablation for atrial fibrillation (AF).

Background: Linear ablation for AF may result in macroreentrant AT.

Methods: Three hundred forty-nine patients (age 54 +/- 11 years) underwent LA circumferential ablation for AF (paroxysmal in 227).

Computed tomographic analysis of the anatomy of the left atrium and the esophagus: implications for left atrial catheter ablation.

Background: During left atrial (LA) catheter ablation, an atrioesophageal fistula can develop as a result of thermal injury of the esophagus during ablation along the posterior LA. No in vivo studies have examined the relationship of the esophagus to the LA. The purpose of this study was to describe the topographic anatomy of the esophagus and the posterior LA by use of CT.

Noninducibility of atrial fibrillation as an end point of left atrial circumferential ablation for paroxysmal atrial fibrillation: a randomized study.

Background: An anatomic approach of left atrial radiofrequency circumferential ablation (LACA) to encircle the pulmonary veins is often effective in eliminating paroxysmal atrial fibrillation (AF). However, no electrophysiological end points other than voltage abatement and/or conduction slowing or block across ablation lines have been used. It has been unclear whether noninducibility of AF is a clinically useful end point.

Misdiagnosis of atrial fibrillation and its clinical consequences.

Purpose: Computer algorithms are often used for cardiac rhythm interpretation and are subsequently corrected by an overreading physician. The purpose of this study was to assess the incidence and clinical consequences of misdiagnosis of atrial fibrillation based on a 12-lead electrocardiogram (ECG).

Methods: We retrieved 2298 ECGs with the computerized interpretation of atrial fibrillation from 1085 patients.

Prevalence of asymptomatic recurrences of atrial fibrillation after successful radiofrequency catheter ablation.

Introduction: The long-term efficacy of radiofrequency catheter ablation of atrial fibrillation (AF) has been based on patient-reported symptoms suggestive of AF. However, asymptomatic recurrences of AF may remain undetected. The aim of this study was to determine the prevalence of asymptomatic recurrences of AF after an apparently successful catheter ablation procedure for AF.

Retrospective diagnosis of prolonged QT interval and Torsades de Pointes made by analysis of ICD electrograms.

We describe a case where a patient received multiple shocks from his implantable cardioverter defibrillator (ICD) for pause dependent polymorphic ventricular tachycardia. The stored far-field electrograms of the ICD were used to make the diagnosis of prolonged QT interval and Torsades de Pointes retrospectively.

Relative timing of isolated potentials during postinfarction ventricular tachycardia and sinus rhythm.

Background: In postinfarction patients, isolated potentials separated by an isoelectric segment from the ventricular electrogram indicate areas of block. Isolated potentials can be recorded during both sinus rhythm and ventricular tachycardia (VT). In an attempt to differentiate bystander pathways from critical sites within a reentry circuit, we compared the relative timing of isolated potentials during VT and sinus rhythm.

Bundle branch reentrant tachycardia in patients with apparent normal His-Purkinje conduction: the role of functional conduction impairment.

Introduction: His-Purkinje conduction delay, manifested by bundle branch block QRS complex configuration or by HV interval prolongation, is considered an essential condition for maintenance of bundle branch reentrant tachycardia (BBRT).

Methods And Results: Of 178 patients with different types of ventricular tachycardia (VT), 13 were found to have BBRT as the underlying electrophysiologic mechanism. Of these 13 patients (9 men and 4 women; mean age 64 +/- 13 years), 6 had an HV interval < or = 55 msec (group A), and 7 had a prolonged HV interval (> 55 msec; group B) during sinus rhythm (SR).

Analysis during sinus rhythm of critical sites in reentry circuits of postinfarction ventricular tachycardia.

Background: Critical sites within reentry circuits of postinfarction ventricular tachycardia (VT) were identified during sinus rhythm (SR) and VT to determine whether electrogram characteristics during SR may be helpful in identifying successful ablation sites.

Methods: In 33 patients (mean age 67 +/- 11 yrs) with prior infarction, mapping and radiofrequency (RF) catheter ablation of 57 hemodynamically-tolerated VT's (cycle length 478 +/- 96) were performed. The morphologies of electrograms (EGM) at sites of concealed entrainment (CE) were compared during SR and VT.

Prevalence of a shared isthmus in postinfarction patients with pleiomorphic, hemodynamically tolerated ventricular tachycardias.

Introduction: Multiple forms of ventricular tachycardia (VT) after myocardial infarction may result from multiple reentrant circuits that share an isthmus or from separate reentrant circuits. The prevalence of a shared isthmus in patients with multiple hemodynamically tolerated VTs has not been determined.

Methods And Results: Criteria for a shared isthmus consisted of (1) concealed entrainment of >1 VT at a single pacing site; (2) concealed entrainment during VT and a perfect pace map of another VT at the same pacing site; or (3) concealed entrainment of VT of a given morphology that had at least two cycle lengths that varied by at least 100 msec.

Mechanism of ventricular tachycardia termination by pacing at left ventricular sites in patients with coronary artery disease.

Objective: The mechanism by which pacing terminates ventricular tachycardia (VT) may depend on the location of the pacing site relative to the reentry circuit. The purpose of this study was to compare the mechanisms by which pacing terminates VT at left ventricular (LV) sites with and without concealed entrainment (CE) in patients with prior myocardial infarction.

Methods And Results: LV mapping was performed in 29 patients (26 men, 3 women, mean age 67 +/- 11 years, ejection fraction 0.

Efficacy and safety of transvenous atrial cardioversion in patients with mitral valve disease and long-standing atrial fibrillation.

Background: Transvenous internal cardioversion (ICV) of atrial fibrillation (AF) may be successful after unsuccessful external CV. However, the safety and efficacy of ICV in patients with significant mitral valve disease and AF of long duration have not been evaluated prospectively.

Methods: This study included 22 consecutive patients (mean age = 59 +/- 14 years, 12 women) with mitral regurgitation grade = II (n = 14) or after mitral valve replacement (n = 8), who underwent ICV with 3/3 ms biphasic shocks delivered via two defibrillation catheters placed in the right atrium and the coronary sinus, respectively.

Ablation of atypical atrial flutter guided by the use of concealed entrainment in patients without prior cardiac surgery.

Introduction: Mapping techniques have not been systematically evaluated with respect to atypical atrial flutter (AF) not involving the inferior vena cava isthmus. The purpose of this study was to assess prospectively the use of concealed entrainment (CE) in mapping of AF and to assess the clinical benefit of ablation of clinically relevant atypical AF.

Methods And Results: In seven consecutive patients without prior cardiac surgery presenting with atypical AF, mapping was performed in the right and, if necessary, left atrium.

Location of the lower turnaround point in typical AV nodal reentrant tachycardia: a quantitative model.

Introduction: Recent observations suggest that the circuit of AV nodal reentrant tachycardia (AVNRT) may extend down to the His bundle. The purpose of this study was to develop a quantitative model indicating the location of the lower turnaround point in AVNRT.

Methods And Results: Slow pathway modification was performed in 70 patients with typical AVNRT.

Septal Q waves in surface electrocardiographic lead V6 exclude minimal ventricular preexcitation.

Electrocardiograms of 37 consecutive patients with minimal preexcitation (i.e., PR >120 ms, QRS <120 ms) were compared before and after ablation with electrocardiograms of 37 age-matched patients with atrioventricular nodal reentrant tachycardia.