Mechanisms of organized left atrial tachycardias occurring after pulmonary vein isolation.

Background: A proarrhythmic consequence of pulmonary vein (PV) isolation can be a recurrent organized left atrial (LA) tachycardia after ablation. This arrhythmia is frequently referred to as "left atrial flutter," but the mechanism and best ablation strategy have not been determined.

Methods And Results: Isolation of arrhythmogenic PVs was initially performed by segmental ostial PV ablation guided by a circular mapping catheter in 341 patients.

Mechanisms underlying sustained firing from pulmonary veins: evidence from pacing maneuvers and pharmacological manipulation.

Atrial Fibrillation (AF) is often initiated by pulmonary vein (PV) depolarizations. However, sustained PV firing (PVF) is infrequently observed in this population and has not been characterized. In 15 patients undergoing AF ablation we report the response of sustained PVF to pacing and pharmacological maneuvers.

ECG criteria for localizing the pulmonary vein origin of spontaneous atrial premature complexes: validation using intracardiac recordings.

We have shown that pacemapping from each of the pulmonary veins reveals unique surface ECG characteristics. However, application of these criteria to spontaneous atrial premature complexes is often difficult because of obscuration by the prior T wave. We hypothesized that the pulmonary vein of origin of spontaneous atrial premature complexes can be determined by measuring characteristics of the P wave whether or not the P wave was superimposed on the prior T wave.

Implantable cardioverter defibrillator events in patients with asymptomatic nonsustained ventricular tachycardia: is device implantation justified?

Primary prevention trials have demonstrated that patients with coronary disease, reduced left ventricular function, and nonsustained ventricular tachycardia (NSVT) have improved survival with implantable cardioverter defibrillator (ICD) therapy, presumably secondary to effective termination of life-threatening arrhythmias. However, stored intracardiac electrograms were not always available and specific arrhythmias leading to ICD therapy were not always known. We examined the occurrence of ICD events in 51 consecutive patients who match the described patient profile to determine the frequency of appropriate and inappropriate ICD therapy.

Incidence and location of focal atrial fibrillation triggers in patients undergoing repeat pulmonary vein isolation: implications for ablation strategies.

Introduction: The etiology of atrial fibrillation (AF) recurrences after pulmonary vein (PV) isolation is not well described. The aim of this study was to examine the reason for recurrent AF in patients undergoing a repeat attempt at AF trigger ablation.

Methods And Results: Patients with recurrent AF more than 1 month after ablation returned for repeat mapping and ablation.

Change in distant atrial activation patterns during circumferential pacemapping of pulmonic vein ostium: implications for localizing triggers for atrial fibrillation.

Introduction: Unique intracardiac activation patterns recorded from multipolar catheters in the coronary sinus (CS) and posteromedial right atrium (RA) when pacing from ostium (os) of each pulmonic vein (PV) can serve as template for determining PV of origin of atrial premature complexes. Development of an accurate template requires knowledge of variations in activation pattern during pacing from different aspects of same PV.

Methods: In 25 patients undergoing catheter ablation for AF, a decapolar Lasso mapping catheter was placed at PV os of interest and multipolar catheters were placed in CS and RA-medial to crista terminalis (CT).

Quantitative comparison of spontaneous and paced 12-lead electrocardiogram during right ventricular outflow tract ventricular tachycardia.

Objectives: The purpose of this study was to objectively quantify the similarity of 12-lead electrocardiogram (ECG) waveforms using two quantitative metrics, the correlation coefficient (CORR) and the mean absolute deviation (MAD).

Background: Comparison of the 12-lead ECG morphology between ventricular tachycardia (VT) and a pace-map is frequently performed; however, there are no objective criteria for quantifying the similarity between two waveform morphologies.

Methods: During ablation of right ventricular outflow tract (RVOT) VT, 12-lead ECG pace-maps were acquired from three superior septal sites, three superior free wall sites, and before each ablation attempt in 15 patients.

Efficacy and safety of targeted focal ablation versus PV isolation assisted by magnetic electroanatomic mapping.

Introduction: Pulmonary vein (PV) triggers initiate atrial fibrillation (AF). The aim of this study was to compare the outcome of focal PV ablation versus targeted PV electrical isolation aided by multipolar catheter recordings in the coronary sinus (CS) and right atrium and magnetic electroanatomic mapping (MEAM) for drug-refractory AF.

Methods And Results: Multipolar recordings identified PVs with triggers based on PV ostial pace map match for spontaneous and provoked triggers.

Atrial tachycardia successfully treated by electrical isolation of the superior vena cava.

This case report describes a patient with an atrial tachycardia that was difficult to induce and that originated from the superior vena cava. Although the patient had frequent episodes of tachycardia, the tachycardia induced in the electrophysiological laboratory was nonsustained and could not be adequately localized for focal ablation. A circumferential mapping catheter was used to guide electrical isolation of the superior vena cava from the right atrium, curing the tachycardia.

Elevations in ventricular pacing threshold with the use of the Y adaptor: implications for biventricular pacing.

Cardiac resynchronization therapy (CRT) is a new and promising therapeutic option for patients with severe heart failure and intraventricular conduction delay. Patients who are candidates for CRT and have a previously implanted device may utilize a "Y" IS 1 connector to accommodate the coronary sinus lead. This modification has the potential to alter biventricular pacing thresholds.

Electrocardiographic patterns of superior right ventricular outflow tract tachycardias: distinguishing septal and free-wall sites of origin.

Introduction: The superior right ventricular outflow tract (RVOT) septum and free wall are common locations of origin for outflow tract ventricular tachycardias (VT). We hypothesized that (1) unique ECG morphologies of pace maps from septal and free-wall sites in the superior RVOT could be identified using magnetic electroanatomic mapping for accurate anatomical localization; and (2) this ECG information could help facilitate pace mapping and accurate VT localization.

Methods And Results: In 14 patients with structurally normal hearts who were undergoing ablation for outflow tract VT, a detailed magnetic electroanatomic map of RVOT was constructed in sinus rhythm, then pace mapping was performed from anterior, mid, and posterior sites along the septum and free wall of the superior RVOT.

Utility of exit block for identifying electrical isolation of the pulmonary veins.

Introduction: Electrical isolation of the pulmonary veins (PVs) to treat paroxysmal atrial fibrillation (AF) has been described using "entry block" as an endpoint for PV isolation. We describe a new technique for guiding PV isolation, using "exit block" out of the PV after ablation as a criterion for successful isolation.

Methods And Results: A circular mapping catheter was positioned at the os of arrhythmogenic PVs and ablation was performed proximal to the mapping catheter until entry block into the vein was achieved.

Interactions of antiarrhythmic drugs and implantable devices in controlling ventricular tachycardia and fibrillation.

Implantable cardioverter defibrillators (ICDs) have proven highly successful in the treatment of life-threatening ventricular arrhythmias. Despite the efficacy of the ICD in terminating ventricular arrhythmias, antiarrhythmic drugs remain an important adjunct to ICD therapy. The use of antiarrhythmic drug therapy in combination with the ICD is synergistic in terms of beneficial effects, but also has the potential for some adverse interactions.

Percutaneous left atrial appendage occlusion (PLAATO) for preventing cardioembolism: first experience in canine model.

Background: Atrial fibrillation is associated with a high risk for cardioembolic stroke. The left atrial appendage (LAA) is the source of the vast majority of these thromboemboli. A novel implanted device for percutaneous LAA transcatheter occlusion (PLAATO) has been designed to seal the LAA.