Masaki Igarashi

Relationship between the hemoglobin level at hospital arrival and post-cardiac arrest neurologic outcome

BACKGROUND The hemoglobin (Hb) level is an essential determinant of oxygen delivery. The restoration of blood perfusion to vital organs and the capacity for oxygen delivery may be associated with ischemia and reperfusion injuries during cardiac arrest and after cardiac arrest. However, whether the Hb level is associated with neurologic outcome in post-cardiac arrest patients remains unclear. METHODS Emergency medical service information and clinical demographics were compiled for witnessed out-of-hospital cardiac arrest patients with coma after the restoration of spontaneous circulation. The study end point was defined as a favorable neurologic outcome at 28 days. We evaluated the relationship between the Hb level at the time of hospital arrival and the neurologic outcome using univariate analyses and a multivariate logistic regression analysis. RESULTS There were 137 witnessed cardiac arrest patients: 49 (35.7%) survived and 34 (24.8%) achieved a favorable neurologic outcome. Univariate analyses showed that the favorable outcome group was characterized as having a higher Hb level, a younger age, a higher percentage of male patients, and ventricular fibrillation as the initial cardiac rhythm. In a multivariate analysis adjusting for potential confounding factors, the Hb level at the time of hospital arrival (odds ratio, 1.26; 95% confidence interval, 1.00-1.58) was an independent predictor of a favorable neurologic outcome. CONCLUSION A higher Hb level at the time of hospital arrival was associated with a favorable short-term neurologic outcome among post-cardiac arrest patients with a presumed cardiac etiology.

Defibrillation Effects of Intravenous Nifekalant in Patients with Out‐of‐Hospital Ventricular Fibrillation

Nifekalant (NF), a pure K+ channel blocker developed in Japan, has been reported to be effective in the treatment of life‐threatening ventricular arrhythmias. We studied its efficacy in 18 men and 4 women with out‐of‐hospital ventricular fibrillation (VF) admitted to our emergency department between August 2001 and March 2004. The number of DC shocks delivered for out‐of‐hospital VF, serum Na+ and K+, arterial blood pH, and base excess were compared in 8 patients treated with NF, 0.3 mg/kg i.v. followed by a continuous intravenous (group N) versus 14 patients treated with lidocaine, 2 mg/kg, i.v. (group C). The two groups were similar with respect to their baseline characteristics. Sinus rhythm returned in 5 of 8 patients in group N versus 2 of 14 patients in group C (P < 0.05). These seven patients were admitted to the intensive care unit, though all died within 1 month. The results of this study suggest that NF may be effective in defibrillation of out‐of‐hospital VF, though controlled studies are needed to confirm our observations.

Estimating Myocardial Damage and the Need for Surgery in Patients With Valvular Heart Disease by Tl-201 SPECT

Left ventricular myocardial disorders due to volume overload were investigated by Tl-201 myocardial SPECT (Tl-201 SPECT) in patients with aortic or mitral regurgitation, and its utility for timing cardiac valve replacement was studied. There were significant correlations between Tl-201 scores and electrocardiographic changes and the New York Heart Association classification. There also were favorable correlations between Tl-201 scores and the left ventricular end-diastolic dimension and between Tl-201 scores and left ventricular ejection fraction, and a close relationship between the presence of a left ventricular myocardial disorder and left ventricular diameter. These results suggest that myocardial perfusion abnormalities and left ventricular myocardial disorders may accompany left ventricular dilatation owing to volume overload. After valve replacement, left ventricular end-diastolic dimension normalized, and Tl-201 scores improved slightly, suggesting normalization of myocardial perfusion. When moderate or more severe Tl-201 defects are present on Tl-201 SPECT images, in addition to inverted Tl-201 waves on the electrocardiogram or a left ventricular end-diastolic dimension of 65 mm or more, cardiac valve replacement should be considered.

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.