Tetsuo Yagi

Distribution of successful ablation sites of idiopathic right ventricular outflow tract tachycardia.

Background: There are few studies evaluating the distribution of successful ablation sites of idiopathic right ventricular outflow tract (RVOT) arrhythmias using a three‐dimensional electroanatomical mapping system. This study aims to clarify the favorite site of idiopathic RVOT arrhythmias through electroanatomical voltage mapping using the CARTO system (Biosense Webster, Diamond Bar, CA, USA).

Clinical and Electrophysiological Difference Between Idiopathic Right Ventricular Outflow Tract Arrhythmias and Pulmonary Artery Arrhythmias

Characteristics of Pulmonary Artery Arrhythmias. Introduction: The precise incidence and characteristics of ventricular arrhythmias originating from the pulmonary artery have not been fully described. The purpose of this prospective study was to clarify these points.

Reentrant Ventricular Outflow Tract Tachycardia Arising from Focal Scar Detected by Delayed Enhancement Magnetic Resonance Imaging

A 58‐year‐old man was referred to our emergency room with hemodynamically unstable sustained ventricular tachycardia (VT). The morphology of the VT exhibited a left bundle branch block and inferior axis deviation. He had no past history of cardiovascular disease. Echocardiography, cardiac catheterization, cardiac biopsy, gallium scintigram, myocardial scintigram, T1,T2‐weighted magnetic resonance imaging (MRI), and gadolinium‐enhanced cine MRI did not detect any structural heart disease or abnormal cardiac function. However, delayed‐enhancement MRI (DE‐MRI) detected a focal intramural scar within the septal ventricular outflow tract. An electrophysiological study revealed a sustained VT with several morphologies and the entrainment phenomenon. Radiofrequency catheter ablation to the site corresponding to the focal scar detected by DE‐MRI successfully eliminated the VT. (PACE 2012;35:e349–e352)

Prevalence and characteristics of idiopathic right ventricular outflow tract arrhythmias associated with J-waves

AIM The arrhythmogenic relationship between the presence of J-waves during sinus rhythm and idiopathic ventricular tachycardia (VT) or pre-mature ventricular contractions (PVCs) originating from the right ventricular outflow tract (RVOT) has not been reported. The aim of this study was to investigate the prevalence and characteristics of idiopathic RVOT-VT/PVCs associated with J-waves. METHODS AND RESULTS The study enrolled 138 consecutive idiopathic RVOT-VT/PVC patients undergoing radiofrequency catheter ablation (RFCA) and 276 age- and gender-matched control subjects. The prevalence of J-waves was assessed in each cohort, and the clinical and electrophysiological data were compared between the RVOT-VT/PVC patients with J-waves (J-RVOT-VT/PVC group) and those without (non-J-RVOT-VT/PVC group). J-waves were more common among patients with idiopathic RVOT-VT/PVCs than among the matched control subjects (40 vs. 16% P < 0.001). The J-RVOT-VT/PVC group had a higher incidence of sustained VT (25 vs. 5%, P < 0.01), shorter VT cycle length (302 ± 57 vs. 351 ± 58 ms, P < 0.001), and more episodes of syncope (25 vs. 2%, P < 0.001) than did the non-J-RVOT-VT/PVC group. However, no patients demonstrated any ventricular fibrillation (VF) or cardiac sudden death in either group. CONCLUSIONS There was a high prevalence of J-waves in the idiopathic RVOT-VT/PVC patients referred for RFCA. Although patients with idiopathic RVOT arrhythmias associated with J-waves might have a more enhanced arrhythmogenicity than those without J-waves, the significance of those J-waves was limited in terms of the prognosis and VF.

Variability of AV nodal potentials recorded, in vivo: direct demonstration of dual AV nodal physiology.

AbstractObjectives of Study: We developed a method to record extracellular A-V nodal potentials in the beating dog heart, in vivo. Methods: In eleven Na-pentobarbital anesthetized, open-chest dogs, an octapolar electrode catheter (2 mm rings, 2 mm spacing) was inserted through a purse-string suture in the coronary sinus (CS) distal to the ostium and positioned electrographically so that the tip electrode recorded a His bundle (Hb) potential. Results: Stable recordings of A-V nodal potentials (amplitude, 178 ± 94 μV; duration 78 ± 26 msec) were consistently made during sinus rhythm from the second and/or third bipolar pairs of electrodes. Programmed atrial stimulation and vagal stimulation resulted in loss of amplitude and increased duration of the A-V nodal potentials associated with A-H prolongation. In another series of experiments, crushing the sinus node in 6 dogs resulted in AV nodal rhythms with AV nodal potentials of varying amplitudes (132 to 840 μV) and durations (range 25 to 71 msec) as the earliest activation which preceded the Hb, atrial and ventricular deflections. One dog, showing dual AV nodal physiology as documented from the AV nodal function curve, had two distinctly different AV nodal potentials. The low-level, longer duration potentials were associated with longer (slow pathway) A-H intervals; whereas the shorter higher amplitude potentials (fast pathway) showed shorter A-H intervals, each occurring at a critical paced cycle length. Conclusion: We conclude that consistent extracellular AV nodal electrograms can be recorded in vivo although the configuration of these potentials varies depending on heart rate, autonomic stimulation and different arrhythmic conditions such as AV nodal escape rhythms and dual AV nodal physiology.

Effect of Intraatrial Reentry on Initiation of Atrioventricular Reentrant Tachycardia

We studied the effect of intratrial reentry (IAE) on initiation of orthodromic reentrant tachycardia (ORT) in 150 patients with Wolff‐Parkinson‐White syndrome using His‐bundle recording and the atrial extrastimulus technique. IAR was initiated by premature atrial stimulation in 44 patients (29%), and it was followed by ORT in 16 patients (11%). In 8 patients (5%), IAR promoted the initiation of ORT, whereas in 5 patients (3%), IAR inhibited the initiation of ORT. These findings suggest that ORT is frequently induced following IAR. IAR, which was frequently observed during electrophysiological studies, seems to play an important role in the initiation of ORT.