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T Tadera

Publications and source records attributed to T Tadera.

5 recordsLinked to original sources
PubMed2001

Demonstration of the reentrant circuit of verapamil-sensitive idiopathic left ventricular tachycardia: direct evidence for macroreentry as the underlying mechanism.

The exact reentrant circuit of verapamil-sensitive idiopathic left ventricular tachycardia (ILVT) remains unclear. This case report demonstrates the reentrant circuit of ILVT. A 20-pole electrode catheter was placed along the left posterior fascicle during electrophysiologic study. ILVT was reproducibly induced by programmed ventricular stimulation. During the tachycardia, sequential diastolic potentials bridging the entire diastolic period were observed in the recordings from the electrodes positioned from left ventricular mid-septum to inferoapical septum. The slow conduction zone appeared to be composed of a false tendon in this patient. Entrainment of the ILVT from the right ventricular outflow tract at a different pacing cycle length revealed that a dominant conduction delay occurred at the proximal site of the slow conduction zone. Entrainment studies from several sites on the left ventricular septum confirmed that these sites where sequential electrical activity was recorded were included within the reentrant circuit. However, the left posterior fascicle itself seemed to be a bystander. This report provides the direct evidence of macroreentry as the underlying mechanism of this ILVT, adjacent to the left posterior fascicle.

Adult↗
PubMed2000

Exit block of focal repetitive activity in the superior vena cava masquerading as a high right atrial tachycardia.

An unusual case of atrial tachycardia (AT) originating from the superior vena cava (SVC) is reported. A 34-year-old man without structural heart disease underwent catheter ablation for drug-resistant AT. During the tachycardia, low-amplitude spiky electrograms with a cycle length of 120 to 175 msec were recorded in the SVC and exhibited 2:1 exit block to the atria, masquerading as the atrial activation observed with high right AT. These spiky electrograms also were observed during sinus rhythm, but they appeared immediately after the local atrial electrograms. The spikes were traced to a point 3 cm above the junction of the right atrium. Radiofrequency ablation at the site of the earliest appearance of the spike in the SVC successfully eliminated the tachycardia. During the following 15 months, no clinically significant atrial arrhythmias, including atrial fibrillation, occurred. This report indicates that careful mapping, including inside the SVC, will be a requisite in patients with high right atrial tachyarrhythmias.

Adult↗
PubMed1998

Ventriculoatrial block during atrioventricular nodal reentrant tachycardia utilizing multiple retrograde pathways.

A rare case of narrow QRS tachycardia continuing despite the occurrence of VA block is reported. Right ventricular stimulation suggested dual AV nodal physiology. The tachycardia was induced by ventricular premature stimulation, which failed to depolarize the atrium. Two types of tachycardia that had different retrograde conduction sequences, HA intervals, and cycle lengths were induced. The occurrence of VA block did not terminate the tachycardia but transiently prolonged the tachycardia cycle length. These findings suggest the mechanism is AV nodal reentry utilizing multiple retrograde pathways with intranodal reentry bridging the VA block and maintaining the tachycardia.

Bundle of His↗
PubMed1997

Curative percutaneous catheter ablation for various supraventricular and ventricular tachyarrhythmias. Results in 187 consecutive patients during the first five years.

Closed-chest transcatheter electrical ablation (catheter ablation) has been applied to various supraventricular and ventricular tachyarrhythmias as a radical therapeutic technique since its introduction in 1982. Currently, it has become a first line therapy for supraventricular tachyarrhythmias except atrial fibrillation and uncommon types of atrial flutter. We first carried out the ablation procedure in 1991 for the treatment of ventricular tachycardia. Up to February 1997, a total of 187 patients underwent catheter ablation in our institution. The aims of this study are to demonstrate our results of catheter ablation in the early 5 years and to show the usefulness of this new curative method. Successful results were obtained in 168 of 187 patients (overall final success rate: 89.8%). The success rates of each category of tachyarrhythmias were 100/105 patients (95%) with WPW syndrome, 41/46 (89%) with atrioventricular nodal reentrant tachycardia, 7/10 (70%) with atrial flutter, 4/4 (100%) with atrial tachycardia, 2/2 (100%) with medically refractory atrial fibrillation, 13/15 (85%) with idiopathic ventricular tachycardia and 3/7 (43%) with sustained ventricular tachycardia associated with structural heart disease, respectively. Complications that required invasive treatments were observed in 3 patients (2 hemopericardium and 1 complete atrioventricular block). Our results indicate that catheter ablation is highly effective in most categories of tachyarrhythmias and can be applied safely without lethal complications.

Adult↗