Bigeminy on exertion.

BIGEMINY or coupling of beats may involve the atria alone, the ventricles, or both. There are many causes for coupling, the commonest and most important being extrasystoles.1 In extrasystolic bigeminy, there is a premature contraction after each normal beat. The premature beat may orig-immate from the sinoatrial node, the atrium, the atrioventricular node, the atrioventricular bundle, or the venitriele. The last ventricular extrasystolic bigeminy, constitutes more than 80 per cent of cases. The premature contractions may arise from right or left ventriele, and very rarely may arise from the interveni-tricular septum. Thev may originate from one or more foei.2 In ventricular extrasystolio bigeminy the atrial rhythm may be normal or abnormal. Atrial fibrillation is seen in nearly 40 per cenrt of cases; overdosage of digitalis is the main cause of coupling. The aim of the present study is to report the occurrence of v-enitricular extrasystolie bi-:geminy on' exertioni. Figure 1 Lead V2 from an electrocardiogram of a 51-year-old clerk. Upper tracing, at rest; lower tracing, after the Master exercise test. 32 Material Case 1 A 40-year-old engineer reported irregular heart action on effort. Physical examination was within normal limits, and electrocardiography showed a normal tracing except for incoimiplete right bundle-branch block as evidenced by deep S waves in leads II and III, and an rsr' pattern in V1. The Master exercise test3 was performned and showed ventricular extrasystolic bigenminy, every normal beat being followed by a premature contraction. After 10 ininutes of bed rest, the bigeminy disappeared. One month later, the patient was seen again because of the same discomfort. Electrocardiography again revealed similar findings. One week later, bigeminv was not seen after exertion. Case 2 A 51-year-old clerk on routine physical examination showed no abnormality except occasional premature beats. Electrocardiogranms before and after the Master exercise test (fig. 1) showed coupling on exertion and returned to the previous status within 2 iiiinutes. At a second examination a few days later the electrocardiogranm was exactly the sanie as the previous record. The patient was instructed to omiiit cigarettes and coffee amid tea. After a week on this reginiei, exercise did not precipitate vemitricular preima-ture comitractions. A 25-year-old woman with precordial discomii-fort showed onlym-iultiple irregularly spaced extrasystoles due to multiple ummifocal premature beats (fig. 2A). On exercise this irregular rhythm changed to bigenminy (fig. 2B). After 10 days of rest and potassiumll citrate, extrasystoles were not seen at rest (fig. 2C), …