[Syncope in 3rd degree atrioventricular block. Detection of virus genome in the myocardium]

A 28-year-old woman was admitted after syncope which had been preceded by several flulike episodes. There was no history of any other serious disease. Physical examination was unremarkable. Heart sounds were regular and normal, there were no murmurs.

White cell count was 9400/microliter, with a normal differential count. Erythrocyte sedimentation rate and C-reactive protein were also normal. Virus serology revealed no abnormality. The electrocardiogram (ECG) showed complete (third degree) atrioventricular (AV) block with an idioventricular rhythm of 38 beats/min and right bundle branch block pattern.

A temporary transvenous pacemaker was inserted on the first hospital day. As myocarditis was suspected a right ventricular endomyocardial biopsy was obtained. Histological and immunohistological examinations demonstrated no unequivocal findings. But molecular-biological tests revealed. Coxsackie-B3 virus genome. The pacemaker was removed on the 6th day, when the ECG had shown intermittent second degree AV block. Regular sinus rhythm with a PR interval of 0.18 s was recorded on day 12, and 24-hour ECG monitoring for several days until her discharge on the 18th day confirmed this rhythm throughout.

In aetiologically undetermined disease molecular-biological techniques can be indispensable for the exact diagnosis and may be decisive for administering specific treatment.