Hideyuki Sato

Comparison of late potentials for 24 hours between Brugada syndrome and arrhythmogenic right ventricular cardiomyopathy using a novel signal-averaging system based on Holter ECG.

Background— Late potentials (LP) detected with signal-averaged ECGs are known to be useful in identifying patients at risk of Brugada syndrome (BS) and arrhythmogenic right ventricular cardiomyopathy (ARVC). Because the pathophysiology is clearly different between these disorders, we clarified the LP characteristics of these disorders. Methods and Results— This study included 15 BS and 12 ARVC patients and 20 healthy controls. All BS patients had characteristic ECG changes and symptomatic episodes. All ARVC patients had findings that were consistent with recent criteria. Three LP parameters (filtered QRS duration, root mean square voltage of the terminal 40 ms of the filtered QRS complex, and duration of low-amplitude signals [<40 µV] in the terminal, filtered QRS complex) were continuously measured for 24 hours using a novel Holter-based signal-averaged ECG system. The incidences of LP determination in BS (80%) and ARVC (91%) patients were higher than in healthy controls (5%; P<0.0001 in both) but did not differ between BS and ARVC patients. In BS patients, the dynamic changes of all LP parameters were observed, and they were pronounced at nighttime. On the contrary, these findings were not observed in ARVC patients. When the SD values of the 3 LP parameters (filtered QRS duration, root mean square voltage of the terminal 40 ms of the filtered QRS complex, and duration of low-amplitude signals [<40 µV] in the terminal, filtered QRS complex) over 24 hours were compared for the 2 patient groups, those values in BS patients were significantly greater than those in ARVC patients (P<0.0001 in all). Conclusions— LP characteristics detected by the Holter-based signal-averaged ECG system over 24 hours differ between BS and ARVC patients. Dynamic daily variations of LPs were seen only in BS patients. This may imply that mechanisms of lethal ventricular arrhythmia in BS may be more correlated with autonomic abnormality than that of ARVC.

Assessment of drug-induced proarrhythmias due to pilsicainide in patients with atrial tachyarrhythmias

Pilsicainide, a pure Na+ channel blocker, is a popular antiarrhythmic drug for the management of atrial tachyarrhythmias (AT), in Japan. However, serious drug‐induced proarrhythmias (DIPs) may unexpectedly occur. We assessed the clinical background of AT patients presenting with DIPs caused by pilsicainide.

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.

Obesity Is Associated With the Development of Interstitial Pneumonia Under Long-Term Administration of Amiodarone in Refractory Atrial Fibrillation Patients.

Although oral amiodarone (AMD) has been used for the management of atrial fibrillation (AF), serious complications such as interstitial pneumonia (IP) occur very occasionally. We evaluated which factors were associated with the development of IP under the long-term administration of AMD in patients with refractory AF.This study included 122 consecutive patients (65.8 ± 11.4 years, mean body mass index [BMI] of 23.2 ± 4.3 kg/m(2)) who orally received AMD to inhibit AF between January 2004 and December 2013. Administration of AMD was begun at 400 mg daily as a loading dose, and was continued at a dosage of 50-400 mg daily after the initial loading phase, determined by the control of the arrhythmias and occurrence of side-effects. The clinical factors were compared between the patients with and without adverse effects, especially IP.During an average follow-up period of 49.2 ± 28.2 months, 53 patients (43.4%) were determined to have converted and maintained sinus rhythm. In contrast, adverse effects were detected in 46 patients (37.7%) with AMD. IP occurred in 8 patients (6.6%), thyrotoxicosis in 35 (28.7%), and others in 5 (4.1%). Four (50.0%) out of 8 patients complicated with IP had obesity (BMI > 27 kg/m(2)). Among the clinical factors, only obesity was significantly associated with the development of IP (P = 0.026).In patients with refractory AF, AMD had an antiarrhythmic effect with long-term administration, but greater adverse effects were also observed. Obesity was the most significant factor associated with the development of IP.

Prevalence and prognosis of patients with lone and paroxysmal atrial tachyarrhythmias showing Brugada-type electrocardiograms after class IC antiarrhythmic drug administration but no risk-stratifying factors

Class IC antiarrhythmic drugs, used to prevent paroxysmal atrial tachyarrhythmias (ATs), are well known to effectively unmask the electrocardiogram (ECG) pattern of Brugada syndrome. We used these drugs to investigate the prevalence and prognosis of patients with lone and paroxysmal ATs and Brugada‐type ECGs.

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.nnMethod 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.nnResult 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.nnConclusion 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.nnMethod 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.nnResult 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.nnConclusion 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.nnMethod 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.nnResult 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.nnConclusion TV was available for slower VT at the timing in the range between -20ms and +60ms, and not for TdP and VF.