Shigeru Oshima

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.

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.

The Characteristics and Distribution of the Scar Tissue Predict Ventricular Tachycardia in Patients with Advanced Heart Failure

Background: Contrast‐enhanced magnetic resonance imaging (CMR) identifies scar tissue as hyperenhanced areas. We sought to clarify the relationship between the scar characteristics and occurrence of sustained ventricular tachycardia (VT) in patients with advanced heart failure.

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

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

Retrograde Purkinje Potential Activation During Sinus Rhythm Following Catheter Ablation of Idiopathic Left Ventricular Tachycardia

Idiopathic Left VT and Purkinje Potentials. We describe two patients with idiopathic left ventricular tachycardia that were cured by radiofrequency catheter ablation. Tachycardia was inducible by ventricular stimulation and was verapamil sensitive. Two distinct presystolic potentials (PI and P2) were recorded during tachycardia in the mid‐septal or inferoapical area, but only one potential (P2) was recorded during sinus rhythm. After catheter ablation at this site, the PI potential was noted after the QRS complex during sinus rhythm, while the P2 was still observed before the QRS complex. The P1 potential showed a decremental property during atrial or ventricular pacing. These data suggest that Purkinje tissue with decremental properties was responsible for the tachycardia mechanism, and that the reentry circuit involving this tissue is likely to be of considerable size.

Nontransmural Scar Detected by Magnetic Resonance Imaging and Origin of Ventricular Tachycardia in Structural Heart Disease

Background: Contrast‐enhanced magnetic resonance imaging (CMR) identifies scar tissue as an area of delayed enhancement (DE). The scar region might be the substrate for ventricular tachycardia (VT). However, the relationship between the occurrence of VT and the characteristics of scar tissue has not been fully studied.

Hybrid Therapy of Radiofrequency Catheter Ablation and Percutaneous Transvenous Mitral Commissurotomy in Patients With Atrial Fibrillation and Mitral Stenosis

AF Ablation and PTMC.u2002Background: The rhythm control of atrial fibrillation (AF) associated with mitral stenosis (MS) is often difficult using antiarrhythmic drugs (AADs), even after a percutaneous transvenous mitral commissurotomy (PTMC). Few studies have examined the efficacy and safety of simultaneously performing radiofrequency catheter ablation (RFCA) and a PTMC in patients with MS and AF.

Ablation of idiopathic ventricular tachycardia in two separate regions of the outflow tract : Prevalence and electrocardiographic characteristics

Few studies have clarified the prevalence and characteristics of idiopathic outflow tachycardia (OT‐VT) with an altered QRS morphology after radiofrequency catheter ablation (RFCA), requiring additional RFCA applications at a different portion of the outflow tract (OT) to abolish the OT‐VT. Among 344 patients (97 VTs and 247 premature ventricular contractions), 12 (3.5%; VTs‐7, PVCs‐5; 6 women) had dynamic QRS morphology changes following the RFCA, requiring additional RFCA applications at a different portion to abolish the OT‐VT. In 8 of 12 patients (67%), this phenomenon occurred following RFCA at right (RVOT; n=7) or left ventricular (LVOT; n=1) endocardial sites of the OT: The second OT‐VT was consistently associated with an increase in the R‐wave amplitude in the inferior leads, and in five it was finally abolished by RFCA at the left sinus of Valsalva (LSV). Conversely, in four patients (33%), the second OT‐VT appeared after RFCA at the LSV: two required additional RFCA applications at the LVOT to abolish the second OT‐VT, and one at the RVOT, and all were associated with a decrease in the R‐wave amplitude in the inferior leads. This kind of dynamic QRS morphology change was often observed when RFCA was applied to either the first or second OT‐VT at a right or left ventricular endocardial site, with the other site being the LSV. A detailed continuous observation of the QRS morphology, especially of the R‐wave in the inferior leads, is important for identifying changes in the QRS morphology during RFCA.

Retrograde supernormal conduction in concealed accessory atrioventricular pathway following catheter ablation.

Supernormal Conduction in Concealed Kent Following Ablation. A case is presented of a 63‐year‐old woman with a concealed accessory pathway that exhibited retrograde supernormal conduction after radiofrequency catheter ablation. Although ventricular pacing at a slow rate revealed no retrograde conduction over the accessory pathway following ablation, the tachycardia recurred 15 months later. During ventricular pacing there was retrograde 1:1 conduction over the accessory pathway at a fast rate while there was intermittent VA dissociation with rare retrograde conduction at the slower rate. Ventricular extrastimulus testing demonstrated a supernormal conduction zone of the coupling interval. Thus, accessory pathways may exhibit supernormal conduction after catheter ablation. Pacing should be performed at both slow and fast rates to confirm the presence of conduction block following ablation.

Magnetic Resonance Imaging is Superior to Cardiac Scintigraphy to Identify Nonresponders to Cardiac Resynchronization Therapy

Background: Left ventricular (LV) postero‐lateral scar and total scar burden are factors responsible for a poor response to cardiac resynchronization therapy (CRT). Contrast‐enhanced magnetic resonance imaging (CMR) and 99mTc‐2‐methoxy isobutyl isonitrile single photon emission computed tomography (SPECT) perfusion imaging are widely used to detect myocardial scar tissue; however, their ability to detect regional scars and predict a positive response to CRT has not been fully evaluated.