Akihiko Nogami

Development and Validation of an ECG Algorithm for Identifying the Optimal Ablation Site for Idiopathic Ventricular Outflow Tract Tachycardia

Introduction: Idiopathic ventricular outflow tract tachycardia or premature ventricular contractions (OT‐VTs) can originate from several different sites in the outflow tract, including the left ventricular (LV) endocardium and epicardium. The aims of this study were (1) to develop an ECG algorithm to predict the origin of OT‐VT and (2) to test prospectively the accuracy of the algorithm.

How to Diagnose, Locate, and Ablate Coronary Cusp Ventricular Tachycardia

Catheter Ablation of LVOT VT from a Coronary Cusp. Introduction: Although radiofrequency energy usually is applied to the most favorable endocardial site in patients with outflow tract ventricular tachycardia, there are still some patients in whom the tachycardia can be ablated only from an epicardial site. We established the characteristics and technique of catheter ablation from both the left and right coronary cusps to cure left ventricular outflow tract ventricular tachycardia.

Purkinje-related arrhythmias part I: monomorphic ventricular tachycardias.

Purkinje‐related monomorphic ventricular tachycardias (VTs) can be classified into four distinct groups: (1) verapamil‐sensitive left fascicular VT, (2) Purkinje fiber‐mediated VT post infarction, (3) bundle branch reentry (BBR) and interfascicular reentry VTs, and (4) focal Purkinje VT. There are three subtypes of fascicular VTs: (1) left posterior fascicular VT with a right bundle branch block (RBBB) configuration and superior axis; (2) left anterior fascicular VT with an RBBB configuration and right‐axis deviation; and (3) upper septal fascicular VT with a narrow QRS configuration. The mechanism of the fascicular VT is macroreentry. While the antegrade limb of the circuit is a midseptal abnormal Purkinje fiber in the anterior and posterior fascicular VTs, the antegrade limb of the upper septal fascicular VT is both the anterior and posterior fascicles, and the retrograde limb is a midseptal abnormal Purkinje fiber. Purkinje fiber‐mediated VT post infarction also exhibits verapamil sensitivity, and the surviving muscle bundles within the myocardium and Purkinje system are components of the reentry circuit. BBR‐VT and interfascicular reentry VT are amenable to being cured by the creation of bundle or fascicular block. The mechanism of focal Purkinje VT is abnormal automaticity from the distal Purkinje system, and the ablation target is the earliest Purkinje activation during the VT. It is difficult to distinguish verapamil‐sensitive fascicular VT from focal Purkinje VT by the 12‐lead electrocardiogram; however, focal Purkinje VT is not responsive to verapamil . The recognition of the heterogeneity of these VTs and their unique characteristics should facilitate an appropriate diagnosis and therapy. (PACE 2011; 34:624–650)

Verapamil-Sensitive Left Anterior Fascicular Ventricular Tachycardia: Results of Radiofrequency Ablation in Six Patients

Verapamil‐Sensitive Left Anterior Fascicular VT. Introduction: Verapamil‐sensitive left ventricular tachycardia (VT) with a right bundle branch block (RBBB) configuration and left‐axis deviation bas been demonstrated to arise from the left posterior fascicle, and can be cured by catheter ablation guided by Purkinje potentials. Verapamil‐sensitive VT with an RBBB configuration and right‐axis deviation is rare, and may originate in the left anterior fascicle.

Electrocardiographic Characteristics of Repetitive Monomorphic Right Ventricular Tachycardia Originating Near the His‐Bundle

Introduction: Most idiopathic nonreentrant ventricular tachycardia (VT) and ventricular premature contractions (VPCs) arise from the right or left ventricular outflow tract (OT). However, some right ventricular (RV) VT/VPCs originate near the His‐bundle region. The aim of this study was to investigate ECG characteristics of VT/VPCs originating near the His‐bundle in comparison with right ventricular outflow tract (RVOT)‐VT/VPCs.

Successful catheter ablation of an anteroseptal accessory pathway from the noncoronary sinus of Valsalva.

We describe a patient who underwent radiofrequency catheter ablation of concealed left lateral and anteroseptal accessory pathways. After successful elimination of the concealed left anterolateral accessory pathway, the earliest retrograde atrial activation was located in the His‐bundle region. Complete elimination of the accessory pathway conduction was achieved with a radiofrequency energy application from the noncoronary sinus of Valsalva. (J Cardiovasc Electrophysiol, Vol. 14, pp. 544‐546, May 2003)

Changes in the Isolated Delayed Component as an Endpoint of Catheter Ablation in Arrhythmogenic Right Ventricular Cardiomyopathy: Predictor for Long‐Term Success

Introduction: Although successful ablation of ventricular tachycardia (VT) is feasible in arrhythmogenic right ventricular cardiomyopathy (ARVC), long‐term recurrence is common. The aim of this study was to assess the usefulness of a change in the isolated delayed component (IDC) as an endpoint of the catheter ablation in ARVC.

Purkinje‐related Arrhythmias Part II: Polymorphic Ventricular Tachycardia and Ventricular Fibrillation

There has been growing evidence that the Purkinje network plays a pivotal role in both the initiation and perpetuation of ventricular fibrillation (VF). A triggering ventricular premature beat (VPB) with a short‐coupling interval could arise from either the right or left Purkinje system in patients with polymorphic ventricular tachycardia (VT) or VF, and that can be suppressed by the catheter ablation of the trigger. A focal breakdown in the “gating mechanism” at the Purkinje system resulting in a short‐circuiting of the transmission across the gate at the distal Purkinje network might predispose to reentrant circuits of polymorphic VT/VF. Many investigators also reported the successful ablation of Purkinje‐related VF with an acute or remote myocardial infarction. The same approach with good short‐term results has been reported in a small number of patients with other heart diseases (i.e., amyloidosis, chronic myocarditis, nonischemic cardiomyopathy). Catheter ablation of the triggering VPBs from the Purkinje system can be used as an electrical bailout therapy in patients with VF storm. (PACE 2011; 34:1034–1049)

Retrograde multiple and multifiber accessory pathway conduction in the Wolff-Parkinson-White syndrome : Potential precipitating factor of atrial fibrillation

Retrograde Multiple Accessory Pathway Precipitating AF. Introduction: The determinants of susceptibility to atrial fibrillation (AF) and the existence of accessory pathway conduction have remained unidentified in the Wolff‐Parkinson‐White (WPW) syndrome. We tested the hypothesis that excitation inputs into the atrium over a retrograde multiple or multifiber accessory pathway during AV reentrant tachycardia (AVRT) could precipitate initiation of AF.

Swallowing‐Induced Atrial Tachyarrhythmias: Prevalence, Characteristics, and the Results of the Radiofrequency Catheter Ablation

Background: Detailed information on swallowing‐induced tachyarrhythmias has been lacking.