Right ventricular histological substrate and conduction delay in patients with Brugada syndrome.

The reported pathogenesis of Brugada syndrome is phase 2 reentry resulting from shortening of the epicardial action potential duration at the right ventricular outflow tract (RVOT). However, several studies have revealed a high incidence of ventricular late potentials and high rate of ventricular fibrillation (VF) induced by programmed ventricular stimulation (PVS). The aim of the present study was to evaluate the role of slow conduction at the RVOT for the initiation of VF by PVS and any underlying pathological conditions in Brugada syndrome.

Combined effect of pulmonary vein isolation and ablation of cardiac autonomic nerves for atrial fibrillation.

This study was designed to determine whether endocardial high-frequency stimulation at the pulmonary vein (PV) antrums can localize cardiac autonomic ganglionated plexi (GP) and whether ablation at these sites can evoke a vagal response and provide a long-term benefit after PV isolation (PVI) for atrial fibrillation (AF). Radiofrequency ablation of each PV antrum was performed in 21 patients with paroxysmal AF (n = 17) or persistent (n = 4) AF. In 8 patients with paroxysmal AF, a ring electrode catheter was placed at each PV antrum.

P wave morphology of an arrhythmogenic focus in patients with atrial fibrillation originating from a pulmonary vein or the superior vena cava.

Background: It was hypothesized that atrial premature contractions (APCs) originating in the pulmonary veins (PVs) or superior vena cava (SVC) can be localized by evaluating characteristics of the P wave.

Methods And Results: Thirty-eight patients with paroxysmal atrial fibrillation were studied. P wave polarity and morphology of the ECGs during pacing from PVs were analyzed and compared to those of APCs originating from PVs.

Three-dimensional reconstruction of the coronary sinus with rotational angiography.

Background: High-speed rotational coronary venous (CV) angiography (RCVA) permits dynamic, multi-angle visualization of the CV anatomy.

Methods And Results: RCVA uses a rapid isocentric rotation over a 108 degrees arc, right anterior oblique (RAO) 54 degrees to left anterior oblique (LAO) 54 degrees, in 4 s. Three-dimensional models of the venous tree were reconstructed, and the rotational images were analyzed using a full range of gantry angles, providing the operator with considerably more information about the CV anatomy than standard coronary sinus angiography images (SCVA).

Anatomic and electrophysiologic differences between chronic and paroxysmal atrial flutter: intracardiac echocardiographic analysis.

Background: It remains unknown why atrial flutter (AFL) occurs as either a chronic or paroxysmal arrhythmia.

Purpose: The aim of the study was to compare intracardiac echocardiographic (ICE) images of the crista terminalis (CT) and transverse conduction properties of the CT between chronic and paroxysmal forms of common AFL.

Methods: Chronic AFL (n = 7) was defined as non-self-terminating AFL lasting >1 month, and paroxysmal AFL (n = 8) was defined as an intermittent arrhythmia with symptomatic episodes of 24 hours maximum duration.

Full-motion two- and three-dimensional pulmonary vein imaging by intracardiac echocardiography after pulmonary vein isolation.

Background: The pulmonary veins (PVs) are topographically complex and motile, so angiographic visualization of the PVs anatomy is limited. An imaging technique that accurately portrays the pulmonary vein (PV) anatomy would be valuable during and after catheter ablation procedures.

Purpose: We investigated whether three-dimensional (3D) intracardiac echocardiography (ICE) can visualize radiofrequency (RF)-induced tissue changes after PV isolation.

Radiofrequency catheter ablation of ventricular tachycardia originating in the left posterior and left anterior fascicles in a patient with prior myocardial infarction.

A 61-year-old man with prior anteroseptal myocardial infarction (ejection fraction: 40%) presented with recurrent episodes of palpitations. Twelve-lead ECG during palpitations showed an incessant ventricular tachycardia (VT1) with right bundle branch block (RBBB) morphology and inferior axis. Electrophysiologic study revealed that the clinical VT originated from the anterolateral left ventricle.

Electrophysiological properties of the atrium after cardioversion of chronic atrial fibrillation: relation to the plasma brain natriuretic peptide level.

Background: Brain natriuretic peptide (BNP) level has been shown to increase in patients with chronic atrial fibrillation (CAF) without overt heart failure (HF). Although atrial electrical remodeling associated with CAF has been described, little is known about the effects of the BNP level on the electrophysiological properties in CAF patients.

Methods And Results: In 42 CAF patients without overt HF, the atrial monophasic action potential duration (MAPD) at pacing cycle lengths (CLs) of 300-800 msec and P-wave signal-averaged electrograms were recorded after cardioversion.

Electrocardiographic and electrophysiologic characteristics in patients with Brugada type electrocardiogram and inducible ventricular fibrillation: single center experience.

Background: The study examined the electrocardiographic and electrophysiologic characteristics in relation to programmed ventricular stimulation (PVS)-induced ventricular fibrillation (VF) in patients with Brugada syndrome.

Methods And Results: Thirty-four patients with a Brugada-type electrocardiogram (ECG) were enrolled. Twelve patients had a type 1 ECG, 12 had a type 2 ECG, and 10 had a type 3 ECG.

Endocardial electrograms from the right ventricular outflow tract after induced ventricular fibrillation in patients with Brugada syndrome.

Background: The pathogenesis of Brugada syndrome (BS) is reported to be phase 2 reentry resulting from shortening of the action potential duration at the epicardial site of the right ventricular outflow tract (RVOT). However, several reports have shown a high incidence of ventricular late potentials (LPs) and a high rate of induction of ventricular fibrillation (VF) by programmed ventricular stimulation (PVS) among patients with BS. The aim of this study was to investigate the role of slow conduction for the initiation of VF by PVS in these patients.

Electrophysiologic and anatomical characteristics of the right atrial posterior wall in patients with and without atrial flutter: analysis by intracardiac echocardiography.

Background: The posterior right atrial transverse conduction capability during typical atrial flutter (AFL) is well known, but its relationship to the anatomical characteristics remains controversial.

Methods And Results: Thirty-four AFL and 16 controls underwent intracardiac echocardiography after placement of a 20-polar catheter at the posterior block site during AFL or pacing. In 31 patients, the effective refractory period (ERP) at the block site was determined as the longest coupling interval that resulted in double potentials during extrastimuli from the mid-septal (SW) and free (FW) walls.

Pulmonary vein isolation for atrial fibrillation in patients with paroxysmal atrial fibrillation and prolonged sinus pause.

Background: Symptomatic prolonged sinus pauses upon termination of atrial fibrillation (AF) are an indication for pacemaker implantation.

Methods And Results: We evaluated the clinical outcomes of 4 patients who showed prolonged sinus pauses (> 2 seconds) upon termination of AF and thus underwent ablation. The ablative procedure included pulmonary vein isolation, superior vena cava isolation, and cavo-tricuspid isthmus ablation.

Prediction of the efficacy of pulmonary vein isolation for the treatment of atrial fibrillation by the signal-averaged P-wave duration.

Background: The noninvasive methods for predicting a successful pulmonary vein isolation (PVI) have not been well described. The aim of this study was to assess the usefulness of the P-wave signal-averaged electrocardiogram (P-SAECG) in predicting the chance of a successful PVI in patients with atrial fibrillation (AF).

Methods: A P-SAECG was recorded before (pre), 1 day after, and 3-4 months after the PVI in 51 AF patients (41, paroxysmal AF; 10, persistent AF).

Anatomical characteristics of the cavotricuspid isthmus in patients with and without typical atrial flutter: Analysis with two- and three-dimensional intracardiac echocardiography.

Introduction: The cavotricuspid isthmus (CTI) is crucial in the ablation of typical atrial flutter (AFL), and consequently the CTI anatomy and/or its relation to resistant ablation cases have been widely described in human angiographic studies. Intracardiac echocardiography (ICE) has been shown to be a useful tool for determining detailed anatomical information. Thus, this technology may also allow the visualization of the anatomical characteristics of the CTI, providing an opportunity to further understand the anatomy.

Inducibility of atrial flutter in patients with atrioventricular nodal reentrant tachycardia.

Background: Previous studies have shown that both atrioventricular nodal reentrant tachycardia (AVNRT) and atrial flutter (AFL) have an area of slow conduction located in the low posterior right atrium near the ostium of the coronary sinus. The aim of this study was to evaluate the inducibility of AFL in patients with AVNRT.

Methods And Results: One hundred and seventy patients were prospectively evaluated for inducibility of tricuspid valve - inferior vena cava isthmus-dependent AFL.

Idiopathic left ventricular tachycardia with a change from left to right axis deviation during radiofrequency catheter ablation.

A 62 year-old-woman presented with a right bundle branch block (RBBB) and left axis deviation (LAD) tachycardia. Radiofrequency (RF) energy was delivered to the left posterior fascicle (LPF) where 2 presystolic Purkinje potentials (P1 and P2) preceding onset of the QRS complex were recorded. During RF energy applications, the QRS morphology of the tachycardia changed from RBBB and LAD to RBBB and right axis deviation without termination of the tachycardia.

Usefulness of the polarity in high-density wide range-filtered bipolar mapping to detect isthmus block during radiofrequency ablation of typical atrial flutter.

Background: The atrial activation sequence around the tricuspid annulus (TA) cannot always be used to establish whether complete block has been achieved across the cavotricuspid isthmus (CTI) during radiofrequency ablation (RFCA) for typical counterclockwise atrial flutter (CCW-AFL).

Aim: We examined whether a change in the polarity of the atrial high-density wide range-filtered bipolar electrograms recorded near the ablation line is an accurate indicator of complete CTI block.

Methods: Nineteen patients with CCW-AFL underwent RFCA.

Recurrence of atrial fibrillation after internal cardioversion of persistent atrial fibrillation: prognostic importance of electrophysiologic parameters.

Background: The purpose of this study was to determine whether the extent of atrial electrical remodeling affects the recurrence of atrial fibrillation (AF) after cardioversion of persistent AF (PAF).

Methods And Results: Internal atrial cardioversion was performed in 47 patients with PAF. The right atrial monophasic action potential duration (RA-MAPD) at pacing cycle lengths (PCLs) of 800-300 ms and P wave signal-averaged electrocardiogram were recorded after cardioversion.

Complete AV block developing in a patient with manifest ventricular preexcitation.

This case report describes a 37-year-old man with manifest atriofascicular and fasciculoventricular connections who developed complete atrioventricular block. After resumption of 1:1 atrioventricular conduction, an electrophysiological study was conducted. During sinus rhythm, manifest ventricular preexcitation was observed and the AH and HV intervals were 80 msec and 50 msec, respectively.

Differential pacing for distinguishing slow conduction from complete conduction block of the tricuspid-inferior vena cava isthmus after radiofrequency ablation for atrial flutter--role of transverse conduction through the crista terminalis.

Background: Partial conduction block has been suggested a predictor of recurrence of atrial flutter (AFL).

Aim: The aim of this study was to assess transverse conduction by the crista terminalis (CT) as a problem in evaluating isthmus block and the usefulness of differential pacing for distinguishing slow conduction (SC) and complete conduction block (CB) across the ablation line.

Methods: We assessed 14 patients who underwent radiofrequency catheter ablation of the eustachian valve/ridge-tricuspid valve isthmus for typical AFL.

Comparison of coronary sinus morphology in patients with and without atrioventricular nodal reentrant tachycardia by intracardiac echocardiography.

Introduction: Dual AV nodal physiology is the electrophysiologic substrate for AV nodal reentrant tachycardia (AVNRT), but the anatomic basis for this arrhythmia remains to be elucidated. Atrial flutter (AFL) has been shown to be more frequently inducible in patients with AVNRT.

Methods And Results: A 3.

Brugada-like electrocardiographic pattern unmasked by fever.

Brugada syndrome is characterized by right bundle branch block morphology and ST-segment elevation in the right precordial leads and a propensity to develop ventricular arrhythmias. Mutations in a cardiac sodium channel gene have been linked to this syndrome, and the ionic mechanisms responsible for the electrocardiographic phenotype are temperature-dependent. This case report describes a patient in whom a typical Brugada ECG pattern developed during fever and could be reproduced at normal body temperature by administration of pilsicainide.

Combined atriofascicular and fasciculoventricular connections.

A 32-year-old man with a 20-year history of palpitation showed a short PQ interval and delta wave on 12-lead ECG. An electrophysiological study showed that the atrio-His (AH) and His-ventricular intervals were not influenced by rapid right atrial pacing or by bolus injection of adenosine triphosphate (ATP). The AH interval was shortened by coronary sinus ostium (CSos) pacing.

Relationship between polarity of the flutter wave in the surface ECG and endocardial atrial activation sequence in patients with typical counterclockwise and clockwise atrial flutter.

Background: The relation between ECG and activation patterns within atria in typical atrial flutter (AFL) patients (pts) has not been defined due to the lack of simultaneous multisite right and left atrial mapping.

Methods: In 13 pts with AFL, a Halo catheter was positioned along tricuspid annulus and multipolar catheters were placed in right atrial appendage, His bundle region, coronary sinus (CS), proximal portion of right pulmonary artery (Bachmann's bundle region, BB) and esophagus (Eso) to record right and left atrial activation simultaneously.

Results: In counterclockwise (CCW) AFL (11 pts), 9 showed negative flutter wave (F) and 2 positive F in the inferior leads.