Itsuki Omori

Prolonged atrial activity due to delayed conduction in the atrium of patients with paroxysmal atrial fibrillation

SummaryWe investigated the relationship between the duration of electrical atrial activity and intra-atrial conduction time to determine whether the prolonged atrial activity was due to delayed conduction in the human atrium. The study included 15 patients with paroxysmal atrial fibrillation (PAF) and 15 control patients. The duration of atrial electrical activity was measured by selecting a minimum electrographic amplitude of 50µV. In patients with PAF, the duration of atrial activity was prolonged in proportion to the delay of interatrial conduction time from the high right atrium to the coronary sinus as the coupling interval of premature extrastimuli was decreased. Both the fragmented atrial activity zone and the interatrial conduction delay zone were wider in patients with PAF than in control patients. It is concluded that assessment of the duration of atrial activity with a minimum amplitude of 50µV is useful in evaluating human atrial vulnerability since it reflects the atrial conduction delay in patients with PAF.

A case of left ventricular aneurysm of uncertain etiology presenting as ventricular tachycardia

A case of a 59-year-old Asian male with several episodes of syncope and palpitation is reported. Electrophysiologic study disclosed that sustained ventricular tachycardia was induced by programmed electrical stimulation at the right ventricular apex. The electrogram in the left ventricular aneurysm showed delayed activities and the fastest depolarization. Entrainment was observed by faster pacing. Left ventriculography showed a large aneurysm and normal coronary arteries. Congenital left ventricular aneurysm is the most likely clinical diagnosis given the lack of past history of chest pain, myocarditis, cardiomyopathy, etc. Congenital aneurysm which presents as ventricular tachycardia is very rare, and has never been reported in an Asian. Medical management has thus far been successful.

Electrophysiological effects of flecainide acetate on stretched guinea pig left atrial muscle fibers

SummaryThe electrophysiological effects of flecainide acetate (3×10−6 M) on stretched atrial tissue were investigated using guinea-pig left atrial muscle fibers. Before stretching, the resting membrane potential was not affected by flecainide at 1 Hz, although the overshoot potential (Eov) and the action potential duration at 50% repolarization (APD50) were slightly but significantly decreased by 2±1 mV and 2±1 msec, respectively. The effective refractory period (ERP) was increased by 3±1 msec. The reduction of

Tachyarrhythmia Provoked by Coughing and Other Stimuli

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Effects of pilsicainide on the atrial fibrillation threshold in guinea pig atria. A comparative study with disopyramide, lidocaine and flecainide.

max was 20.6±1.2%. The half-maximum potential (Vh) of the relationship between

SUPPRESSING EFFECTS OF CAFFEINE ON POSTEXTRASYSTOLIC POTENTIATION IN PAPILLARY MUSCLES OF GUINEA PIGS

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