The significance of AV block I in asymptomatic young men. Variability, some anthropometric data, orthostatic test reaction and physical work capacity.

Twenty-nine young men with AV block I (P-R interval greater than 0.22 sec), without any history of heart disease, have been compared with 112 randomly selected healthy men of the same age. In 24 subjects who were free from concomitant ECG changes the P-R interval was normalized during orthostatic test and/or physical exercise. This group did not differ from the controls regarding anthropometric data and physical work capacity except for a higher heart rate at rest, thus suggesting that in these subjects an occurrence of AV block I has no pathological significance. However, it cannot be excluded that the block is a sequela, for instance, to myocarditis. Three subjects with AV block I and inverted T waves in the precordial leads and two subjects with unchanged P-R intervals to increased sympathetic tone had on average a smaller body size, a higher HR and systolic BP in recumbent position and smaller blood volumes.