[Effects of exercise on mitral regurgitation in healthy subjects]

Transthoracic echocardiography including color Doppler echocardiography and graded exercise (supine bicycle ergometer) were performed to examine both the changes of mitral regurgitation (MR) flow during exercise and the effects of cathecholamine on the MR flow in 20 young males (mean age 19 years) and 9 male long-distance runners (mean age 20 years) with presumably normal hearts. MR flow was detected in 13 of the 20 young males at rest. The severity of MR was mild in 12 subjects, and moderate in 1. After exercise, MR flow vanished in 4 of the 13 subjects (group B). In the other nine subjects, MR flow lasted during and after exercise (group A). In the seven subjects without MR flow at rest, MR flow did not appear during and after exercise (group C). Group A had significantly lower left ventricular ejection fraction than group C at rest (A 64.9 +/- 4.25%, B 69.4 +/- 4.32%, C 73.9 +/- 3.46%; p < 0.05). However, no significant differences were observed in other echocardiographic parameters (including left ventricular end-diastolic dimension, mitral annulus diameter and left atrial diameter), heart rate and serum cathecholamine levels between the three groups before and after exercise. In the nine male long-distance runners, MR flow was detected in six of nine subjects at rest. The severity of MR was mild in all subjects. After exercise, MR flow vanished in two of these six subjects (group A). In the other four subjects, MR flow lasted during and after exercise (group B). In three subjects without MR flow at rest, MR flow did not appear during and after exercise (group C). There were no significant differences in echocardiographic parameters, heart rate and serum cathecholamine levels between the three groups before and after exercise. These data suggest that MR flow detected in healthy subjects correlates with tension and contractility of papillary muscle.