Kazuhiro Takamura

Successful Radiofrequency Catheter Ablation of Nonreentrant Supraventricular Tachycardia Due to Simultaneous Conduction Through Dual Atrioventricular Nodal Pathways

Objectives We evaluated whether pacing algorithms (PA) triggered by onset mechanism (OM) of atrial fibrillation (AF) were actually effective. Methods Ten patients (5males, mean age 67.5+/−7.3years) who received Vitatrons Selection pacemaker with >1 AF during 3months after implantation were included. PA were turned off (phase OFF), selectively turned on based on OM of AF (phase ON), and turned on based on all 4 PA (phase ALL-ON) for 3months by crossover method. We compared atrial pacing dependency (%pacing), number of AF, cumulative AF duration, and number of PAC between each setting. The effect of %pacing on AF was evaluated. Result %pacing was greater during phases ON and ALL-ON (phases OFF: 55.6+/−34.7%, ON: 84.2+/−19.7%, ALL-ON: 90.1+/−14.7%, p=0.0004). Number of AF (229.6+/−381.1, 152.8+/−226.5, 318.3+/−577.7, NS), cumulative AF duration (8240+/−12308min, 4013.1+/−8290.5min, 8656.4+/−18071.2min, NS) and number of PAC (88705.6+/−150316.5, 41525.4+/−48130, 139285.1+/−215336.9, NS) were minimized during phase ON. Number of AF negatively correlated with %pacing (r=−0.457, p=0.01). Conclusions PA decreased AF when those were selectively turned on. Higher %pacing was effective to decrease AF regardless of PA. Carefully chosen PA maximizing %pacing will be effective for AF suppression.

3-D mapping of Left Atrial Conduction Pattern

The purpose of this study is to examine a normal conduction pathway of the left atrium. During pulmonary vein isolation using a three‐dimensional mapping system, we observed the characteristics of the conduction pattern. Subjects consisted of 15 patients with paroxysmal atrial fibrillation (mean age, 62.8 ± 8.4 years). Left atrial activation conduction begins in the interatrial septum, and moves toward the peak of the ridge between the left atrial appendage and left pulmonary vein. In coronary sinus or appendage pacing, conduction was in the opposite direction at the same location. The mean conduction velocity in this area was 2.03 ± 0.43 m/s. Features of decrement conduction were not present. Anatomical position of the appendage differed greatly between patients. A detailed observation using the inner‐cavity view of a three‐dimensional mapping system also showed that the peak of the ridge reached the center of the roof.

16. ICD: Defibrillation Threshold Testing & Other Issues

Purpose Electrical cardioversion for ventricular arrhythmias (VAs) contained of ventricular tachycardia (VT), ventricular fibrillation (VF) and torsades de pointes (TdP), was established to be effective for VAs. Little is known about which case should have an effect on chest thump version (TV) in patients with VAs. Method Subjects were 18 patients (Male: Female = 9:9, mean age 61±20 years old). TV was done for 28 episodes in VT, 8 episodes in VF, and 5 episodes in TdP. TV was performed after onset of symptoms within one minutes, and electrocardiogram (ECG) monitor was analyzed. Heart beats were averaged with 10 beats of VF and TdP. The time from Q wave to TV was measured from ECG monitoring in VT patients. Result TV successfully terminated VT in 12 of 28 episodes, VF in 1 of 8 episodes, and 1 of 5 episodes. TV terminated VT in the range between -20ms and +60ms. The mean cycle length of VT was 284±30ms, VF was 238±21ms, and TdP was 270±25ms, respectively. The mean cycle length of successful TV was significantly longer than that of failed TV in VT (358±57ms vs 289±59ms, p<0.01). There was no acceleration of VT in this study. Conclusion TV was available for slower VT at the timing in the range between -20ms and +60ms, and not for TdP and VF.

Efficacy of Chest Thump Version for Ventricular Arrhythmias

Purpose Electrical cardioversion for ventricular arrhythmias (VAs) contained of ventricular tachycardia (VT), ventricular fibrillation (VF) and torsades de pointes (TdP), was established to be effective for VAs. Little is known about which case should have an effect on chest thump version (TV) in patients with VAs. Method Subjects were 18 patients (Male: Female = 9:9, mean age 61±20 years old). TV was done for 28 episodes in VT, 8 episodes in VF, and 5 episodes in TdP. TV was performed after onset of symptoms within one minutes, and electrocardiogram (ECG) monitor was analyzed. Heart beats were averaged with 10 beats of VF and TdP. The time from Q wave to TV was measured from ECG monitoring in VT patients. Result TV successfully terminated VT in 12 of 28 episodes, VF in 1 of 8 episodes, and 1 of 5 episodes. TV terminated VT in the range between -20ms and +60ms. The mean cycle length of VT was 284±30ms, VF was 238±21ms, and TdP was 270±25ms, respectively. The mean cycle length of successful TV was significantly longer than that of failed TV in VT (358±57ms vs 289±59ms, p<0.01). There was no acceleration of VT in this study. Conclusion TV was available for slower VT at the timing in the range between -20ms and +60ms, and not for TdP and VF.

16. ICD: Defibrillation Threshold Testing & Other Issues16.1 Efficacy of Chest Thump Version for Ventricular Arrhythmias

Purpose Electrical cardioversion for ventricular arrhythmias (VAs) contained of ventricular tachycardia (VT), ventricular fibrillation (VF) and torsades de pointes (TdP), was established to be effective for VAs. Little is known about which case should have an effect on chest thump version (TV) in patients with VAs. Method Subjects were 18 patients (Male: Female = 9:9, mean age 61±20 years old). TV was done for 28 episodes in VT, 8 episodes in VF, and 5 episodes in TdP. TV was performed after onset of symptoms within one minutes, and electrocardiogram (ECG) monitor was analyzed. Heart beats were averaged with 10 beats of VF and TdP. The time from Q wave to TV was measured from ECG monitoring in VT patients. Result TV successfully terminated VT in 12 of 28 episodes, VF in 1 of 8 episodes, and 1 of 5 episodes. TV terminated VT in the range between -20ms and +60ms. The mean cycle length of VT was 284±30ms, VF was 238±21ms, and TdP was 270±25ms, respectively. The mean cycle length of successful TV was significantly longer than that of failed TV in VT (358±57ms vs 289±59ms, p<0.01). There was no acceleration of VT in this study. Conclusion TV was available for slower VT at the timing in the range between -20ms and +60ms, and not for TdP and VF.

P.1. Supraventricular Arrhythmias

Objectives We evaluated whether pacing algorithms (PA) triggered by onset mechanism (OM) of atrial fibrillation (AF) were actually effective. Methods Ten patients (5males, mean age 67.5+/−7.3years) who received Vitatrons Selection pacemaker with >1 AF during 3months after implantation were included. PA were turned off (phase OFF), selectively turned on based on OM of AF (phase ON), and turned on based on all 4 PA (phase ALL-ON) for 3months by crossover method. We compared atrial pacing dependency (%pacing), number of AF, cumulative AF duration, and number of PAC between each setting. The effect of %pacing on AF was evaluated. Result %pacing was greater during phases ON and ALL-ON (phases OFF: 55.6+/−34.7%, ON: 84.2+/−19.7%, ALL-ON: 90.1+/−14.7%, p=0.0004). Number of AF (229.6+/−381.1, 152.8+/−226.5, 318.3+/−577.7, NS), cumulative AF duration (8240+/−12308min, 4013.1+/−8290.5min, 8656.4+/−18071.2min, NS) and number of PAC (88705.6+/−150316.5, 41525.4+/−48130, 139285.1+/−215336.9, NS) were minimized during phase ON. Number of AF negatively correlated with %pacing (r=−0.457, p=0.01). Conclusions PA decreased AF when those were selectively turned on. Higher %pacing was effective to decrease AF regardless of PA. Carefully chosen PA maximizing %pacing will be effective for AF suppression.

P.1. Supraventricular ArrhythmiasP.1.2 Successful Radiofrequency Catheter Ablation of Nonreentrant Supraventricular Tachycardia Due to Simultaneous Conduction Through Dual Atrioventricular Nodal Pathways

Objectives We evaluated whether pacing algorithms (PA) triggered by onset mechanism (OM) of atrial fibrillation (AF) were actually effective. Methods Ten patients (5males, mean age 67.5+/−7.3years) who received Vitatrons Selection pacemaker with >1 AF during 3months after implantation were included. PA were turned off (phase OFF), selectively turned on based on OM of AF (phase ON), and turned on based on all 4 PA (phase ALL-ON) for 3months by crossover method. We compared atrial pacing dependency (%pacing), number of AF, cumulative AF duration, and number of PAC between each setting. The effect of %pacing on AF was evaluated. Result %pacing was greater during phases ON and ALL-ON (phases OFF: 55.6+/−34.7%, ON: 84.2+/−19.7%, ALL-ON: 90.1+/−14.7%, p=0.0004). Number of AF (229.6+/−381.1, 152.8+/−226.5, 318.3+/−577.7, NS), cumulative AF duration (8240+/−12308min, 4013.1+/−8290.5min, 8656.4+/−18071.2min, NS) and number of PAC (88705.6+/−150316.5, 41525.4+/−48130, 139285.1+/−215336.9, NS) were minimized during phase ON. Number of AF negatively correlated with %pacing (r=−0.457, p=0.01). Conclusions PA decreased AF when those were selectively turned on. Higher %pacing was effective to decrease AF regardless of PA. Carefully chosen PA maximizing %pacing will be effective for AF suppression.