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Keiichi Inada

Publications and source records attributed to Keiichi Inada.

9 recordsLinked to original sources
PubMed2006

Dual mechanisms underlying pulmonary vein tachycardias in a patient with paroxysmal atrial fibrillation.

We report a case of a 46-year-old man with paroxysmal atrial fibrillation who underwent pulmonary vein isolation. After a complete isolation of each pulmonary vein was performed, two different types of pulmonary vein tachycardia appeared: a regular tachycardia in the left inferior pulmonary vein with a supposed reentrant mechanism, and an irregular tachycardia in the right superior PV showing a nonreentrant character.

Atrial Fibrillation↗
PubMed2006

Behavior of atrial ectopic beats before and after pulmonary vein isolation in patients with atrial fibrillation: a reduction in the number and arrhythmogenicity of ectopic firings.

BACKGROUND: No studies evaluating in a quantitative manner the effect of pulmonary vein (PV) isolation on the behavior of atrial premature beats have been reported. OBJECTIVES: The purpose of this study was to reveal the behavior of atrial premature beats before and after PV isolation in patients with paroxysmal atrial fibrillation (AF). METHODS: In 108 patients free from AF following PV isolation, both the number of atrial premature beats and their coupling intervals before and following PV isolation were evaluated with periodic 24-hour ambulatory monitoring. RESULTS: After a successful PV isolation procedure (group 1, n = 78), the number of atrial premature beats significantly decreased with two distinct time courses: an acute reduction on the following day and a subsequent gradual decrease throughout the whole observation period. The mean atrial premature beat coupling interval at baseline was 420 +/- 30 ms, which was significantly prolonged to 560 +/- 100 ms at 3 months after PV isolation (P <.01). Although patients with AF recurrence after PV isolation (group 2, n = 30) had transiently depressed atrial premature beats shortly after the procedure, they recovered to the former level 3 months after PV isolation. Repeat PV isolation targeting the reconnected PVs successfully suppressed these residual atrial premature beats both in their number and the coupling interval in a manner similar to those in group 1. CONCLUSION: Successful PV isolation reduced the number of atrial premature beats with both rapid and gradual time courses. The residual atrial premature beats appeared less arrhythmogenic, with longer coupling intervals than those at baseline. AF recurrences after PV isolation were associated with increased atrial premature beat number and shortened coupling interval, which were depressed by reisolation of reconnected PVs.

Atrial Fibrillation↗
PubMed2005

Nicorandil inhibits serum starvation-induced apoptosis in vascular endothelial cells.

The Impact Of Nicorandil in Angina (IONA) randomized trial showed a significant reduction in coronary events, in patients with stable angina treated with a KATP channel opener, nicorandil. However, the impact of nicorandil on endothelial apoptosis remains to be examined. We tested the hypothesis that nicorandil has anti-apoptotic effects in endothelial cells (ECs). Apoptosis was induced by serum starvation in the culture media in human umbilical vein endothelial cells. We examined the effects of nicorandil on endothelial cell apoptosis. Cell viability after serum starvation was significantly higher in the nicorandil-treated group compared with the control group (81 +/- 8% vs. 63 +/- 3%, P < 0.01). Apoptosis, as detected by caspase 3 activation and Hoechst 33258 assay, induced by serum starvation was also effectively abrogated by the treatment of nicorandil (100 muM). The protective effects of nicorandil on endothelial survival were significantly inhibited by a specific mitochondrial KATP channel blocker, 5-Hydroxydecanoic acid. A mitochondrial permeability transition pore activator significantly abolished the anti-apoptotic effect of nicorandil in endothelial cells, indicating that the mechanism of protective effect of nicorandil is involved in the mitochondrial apoptotic pathway although it affects neither Bcl-2 nor Bax protein expression levels. In conclusion, nicorandil inhibits serum starvation-induced endothelial cell apoptosis possibly through mitochondrial KATP channels.

Angina Pectoris↗
PubMed2005

Focal source of atrial fibrillation arising from the ostium of the inferior vena cava.

A patient presented with paroxysmal atrial fibrillation (AF) caused by focal rapid discharges arising from the ostium of the inferior vena cava (IVC). Surface ECG showed typical features of AF and flutter when rapid activation at the IVC ostium was conducted to the right atrium in a 1-to-1 and 2-to-1 fashion, respectively. Discrete radiofrequency energy applications at the medial ostium of the IVC completely eliminated the atrial tachyarrhythmias.

Atrial Fibrillation↗
PubMed2005

Atrial septal pacing to resynchronize atrial contraction and improve atrial transport function.

OBJECTIVES: Atrial septal pacing via a trans-septal breakthrough site within the right atrial septum can shorten global atrial activation time, resulting in significant reduction of recurrence of atrial fibrillation events. This study examined whether this pacing method will lead to resynchronization of atrial contraction and its benefit on hemodynamic function can be maintained for 24 months. METHODS: Thirty patients with atrial fibrillation and delayed atrial conduction were enrolled (17 males, 13 females, mean age 73 +/- 7 years). Trans-septal breakthrough site within the right atrial septum was identified through pacing from the dorsal left atrium. Continuous atrial septal pacing at the trans-septal breakthrough site was performed for 24 months. Time difference (TD) between right and left atrial contractions was measured during atrial septal pacing and sinus rhythm by pulse Doppler echocardiography of the trans-tricuspid (P-At) and mitral (P-Am) blood flows (TD = P-Am - P-At). RESULTS: The atrial lead was screwed near the fossa ovalis in 29 of 30 patients. Atrial septal pacing yielded significantly shorter P wave duration (101.9 +/- 10.4 vs 139.6 +/- 14.7 msec, p < 0.001), leading to significant reduction of TD in atrial contraction (-8.8 +/- 10.0 vs 29.8 +/- 13.6 msec, p < 0.001)as compared to sinus rhythm. Both shorter P wave duration and reduced TD during atrial septal pacing remained statistically significant during the follow-up period as compared to sinus rhythm. Both left atrial diameter and A to E ratio of filling waves at mitral valve were significantly decreased at 12 months and remained decreased at 24 months. CONCLUSIONS: Atrial septal pacing at the trans-septal breakthrough site can resynchronize atrial contraction and results in improved hemodynamic effects during 24 months of follow-up.

Aged↗
PubMed2004

A focal source of atrial fibrillation in the superior vena cava: isolation and elimination by radiofrequency ablation with the guide of basket catheter mapping.

Although it has been reported that pulmonary veins sometimes act as a focal driver of atrial fibrillation (AF), little has been reported concerning the contribution of the superior vena cava (SVC) to the maintenance of AF. Here we report a patient with sustained AF due to focal discharges inside the SVC after pulmonary vein isolation procedure. Stepwise radiofrequency current applications with the guide of multielectrode basket catheter mapping first disconnected the arrhythmogenic SVC from the right atrium and then eliminated the tachycardia.

Atrial Fibrillation↗
PubMed2004

Mitral regurgitation disappearance after cibenzoline treatment in a patient with hypertrophic obstructive cardiomyopathy.

Hypertrophic obstructive cardiomyopathy (HOCM), which shows left ventricular outflow pressure gradient (LVPG), is often complicated with mitral regurgitation (MR). We examined a 62-year-old Japanese female with HOCM and MR. Ultrasound echocardiography showed severe MR, asymmetrical septal hypertrophy, systolic anterior movement of the mitral valve anterior leaflet, and left ventricular outflow stenosis. Her LVPG, measured using continuous wave Doppler recording, was 118 mmHg. During heart catheterization, the aortic pressure and left ventricular pressure were simultaneously measured. An intravenous injection of 70 mg cibenzoline decreased the LVPG from 110 mmHg to 16 mmHg. Left ventriculography was performed immediately after the injection and did not show MR. This clearly demonstrates that cibenzoline decreases LVPG in patients with HOCM and also improves the MR that arises from LVPG.

Cardiomyopathy, Hypertrophic↗
PubMed2003

Coronary artery spasm discovered in thorough examination of perioperative VT in a 26-year-old Japanese male.

We thoroughly examined a 26-year-old Japanese male who experienced perioperative ventricular tachycardia. After inhaling sevoflurane, his nasal cavity was soaked with 1:100,000 epinephrine and he was intubated through the nose. Junctional tachycardia occurred five minutes after intubation, changing to ventricular tachycardia. Six-time cardioversion was required to stop the ventricular tachycardia. Echocardiography immediately following the event showed diffuse hypokinesis, and an electrocardiogram showed an inversion of T waves in II, III, aVF and V4-6. Both returned to normal within a few days. Tl scintigraphy revealed a normal perfusion image. Coronary angiography showed a normal coronary, but an injection of acetylcholine induced vasospasm in the right coronary artery. Examination of left ventricular tissue yielded no specific findings. During electrophysiological tests, ventricular tachycardia could not be induced even in the presence of isoprenaline. This is a very young case to elicit vasospasm in the coronary artery with no underlying heart disease. Although the relationship between perioperative ventricular tachycardia and coronary spasm is unknown, cardiac events can occur during anesthesia in young and low-risk patients.

Acetylcholine↗