Takashi Kaku

Right bundle branch block without overt heart disease predicts higher risk of pacemaker implantation: The study of atomic-bomb survivors☆☆☆

BACKGROUND We investigated the clinical course of complete right bundle branch block (RBBB) or RBBB with axis deviation (AD) in terms of subsequent pacemaker implantation for high-degree atrioventricular (AV) block or sick sinus syndrome (SSS). METHODS AND RESULTS Among the 16,170 atomic-bomb survivors in our biennial health examination between July 1967 and December 2010, we detected 520 newly-acquired RBBB subjects with no organic heart disease, and selected 1038 age- (at RBBB diagnosis) and sex-matched subjects without RBBB to serve as comparison subjects. Multivariate Cox regression analysis was used to estimate the hazard ratios (HRs) for the risk of pacemaker implantation due to all causes, AV block or SSS between RBBB and comparison subjects and between RBBB subjects with and without AD. The risk of pacemaker implantation for RBBB was 4.79 (95% confidence interval [CI] 1.89-12.58; P=0.001), 3.77 (95% CI, 1.09-13.07; P=0.036), and 6.28 (95% CI, 1.24-31.73, P=0.026) when implantation was for all causes, AV block and SSS, respectively. RBBB subjects with AD had a higher risk for all-cause pacemaker implantation than subjects without AD (HR, 3.03; 95% CI, 1.00-9.13, P=0.049). RBBB subjects with AD were younger than subjects without AD at the time of RBBB diagnosis (59.4±7.6 vs 74.4±3.1 years old, P=0.019), and their progression from diagnosis to pacemaker implantation took longer (15.1±6.6 vs 6.4±3.0 years, P=0.032). CONCLUSIONS RBBB, especially with AD, progresses to AV block and SSS that requires pacemaker implantation; the mechanisms by which the conduction defect progresses differ among patients with and without AD.

Benefit of monitoring the level of blood flecainide acetate in an elderly patient with ventricular premature contractions

A 67-year-old woman without organic heart, disease had symptomatic ventricular premature contractions. Because class Ia, Ib and IV antiarrhythmic drugs did not prevent the premature contractions, the patient was treated with flecainide acetate at a dose of 50 mg t.i.d. Adverse reactions were noted. After measurement of the blood drug level, the dose was reduced to 50 mg b.i.d. The adverse reactions disappeared, and the arrhythmia was controlled. Flecainide acetate has a relatively long blood elimination half-life and a narrow safety margin. When some antiarrhythmic drugs are used in elderly patients, blood drug level monitoring is useful in preventing adverse reactions and in designing appropriate therapy.

Ruptured Aortic Aneurysm Complicating Coarctation of the Aorta Two Autopsied Cases with Unusual Rupture

Two cases of aortic aneurysm complicating aortic coarctation with unusual rupture were reported. The first case is a 66-year-old female with aneurysm of the descending thoracic aorta. The coarctation of the aorta was located at lower thoracic aorta and the aneurysm was formed proxymal to the coarcta tion. The aneurysm protruded backwards being accompanied by osteolysis of ribs and finally ruptured extracorporeally at the left subscapular region. The second case is a 28-year-old male with mycotic aneurysm that occurred im mediately distal to the coarctation of the aorta. Streptococcus viridans was isolated by blood culture. The aneurysm was ruptured to the esophagus. The mechanisms of aneurysm formation in patients with coarctation of the aorta were discussed.