Shoji Hirasawa

Combined effects of up- and downstream therapies on atrial fibrillation in a canine rapid stimulation model

BACKGROUND Recent reports suggest angiotensin receptor blockers (ARBs) and some antiarrhythmic agents affect atrial remodeling in atrial fibrillation (AF). We evaluated the effect of combination therapy with olmesartan (Olm) and bepridil (Bep) in a canine model of AF. METHODS AND RESULTS An atrial stimulation device was implanted in 10 dogs undergoing 6-week pacing at 400 bpm. They were divided into Olm (2 mg/kg/day) (n=5) and Olm+Bep (Olm, 2 mg/kg/day; Bep, 10 mg/kg/day) groups (n=5). Atrial effective refractory period (AERP), conduction velocity (CV), and AF inducibility were evaluated weekly, and hemodynamics, atrial histology, and mRNA expression and protein expression of ion-channel and gap junction-related molecules at 6 weeks. Data were compared between groups and with non-pacing control and pacing-control groups from our previous report. The pacing-control group exhibited shortened AERP, decreased CV, increased AF inducibility and tissue fibrosis, and down-regulated L-type Ca(2+) channel (LCC), SCN5A, Kv4.3 and connexin43 (Cx43). By comparison, the Olm group exhibited suppression of the decrease in CV and of the increase in AF inducibility, but no change in AERP shortening. The Olm+Bep group exhibited suppression of AERP shortening as well as the greatest decrease in AF inducibility. Histologically, tissue fibrosis was suppressed in Olm and Olm+Bep groups. Down-regulation of Cx43 was partly suppressed in the Olm group while that of LCC, SCN5A, and Cx43 was suppressed in the Olm+Bep group. CONCLUSION Olm and Bep in combination suppressed AF inducibility more strongly than Olm alone, and may be more useful in the suppression of AF.

Acute myocardial infarction involving double vessel total occlusion of the left anterior descending and left circumflex arteries: A case report

A 66-year-old Japanese man complained of chest pain consistent with acute myocardial infarction (AMI). His electrocardiogram showed ST segment elevation in the anterior and inferior leads. Emergency coronary angiography revealed occlusion of the proximal left anterior descending artery (LAD) and middle left circumflex artery (LCx). An intra-aortic balloon pump (IABP) was inserted to restore antegrade coronary flow in these vessels. Coronary stents were subsequently implanted at the culprit lesions. Although previous reports of multivessel coinstantaneous AMI are rare and indicate a poor prognosis, he had a relatively benign course and was discharged with New York Heart Association functional class I without post-operational complications.

Effect of nifekalant on life-threatening ventricular arrhythmias in patients with cardiopulmonary resuscitation or during the perioperative state

Background: Nifekalant is a unique class III anti‐arrhythmic agent with a strong effect on prolonging the myocardial refractoriness, but its clinical effect is still unclear. In this study, we evaluated the effect of nifekalant on life‐threatening ventricular arrhythmias and compared the clinical background between the effective and non‐effective patients in order to clarify the clinical factors which may have an influence on the efficacy of nifekalant.

Morphological Properties of Atrial Fibrillation Waves in Patients with Left Ventricular Dysfunction —Spectral Analysis of Atrial Fibrillation Waves in Dilated Cardiomyopathy—

Introduction: Although the atrial fibrillation cycle length (FCL) is considered to shorten in persistent atrial fibrillation (AF) as a result of electrical remodeling, whether a long‐term change remains in FCL in patients with left ventricular (LV) dysfunction is uncertain. Morphological properties of AF waves were analyzed in patients with dilated cardiomyopathy (DCM). Methods and Results: The study population consisted of 43 patients with persistent AF, and they were divided into a DCM group (n = 14) and a control group (n = 29). Fibrillation waves from surface ECG lead V1 were purified by subtracting the QRS‐T complex template. Power spectral analysis was performed by Fast Fourier Transformation, and the mean FCL was determined by the peak power frequency in 20 epochs at each recording. The LV ejection fraction was lower in the DCM group (50 ± 18%) than the control (63 ± 8%, p = 0.001). The mean FCL was shorter in the DCM group (132 ± 14 ms) than the control (151 ± 23 ms, p = 0.007) and there was a significant correlation between the FCL and LV dimensions (p = 0.03). Conclusion: In patients with persistent AF and LV dysfunction, FCL was shorter in comparison with the control, and seemed to be influenced by LV dimensions.