Left ventricular function during isometric exercise (handgrip): significance of an atrial gallop (S₄)

The clinical significance of an atrial (S₄) gallop remains controversial. The present study was undertaken to investigate whether the development of an atrial gallop (S₄) during stress correlated more closely with an abnormal left ventricular function than the presence of an S₄ at rest. Left ventricular function was assessed by relating changes in SWI to left ventricular enddiastolic pressure during isometric exercise at 25 per cent and 50 per cent of a maximum voluntary handgrip contraction. A phonocardiogram was recorded continuously during the procedure. Six patients with no S₄ at rest or during isometric exercise all had normal ventricular function curves. Six patients had no atrial gallop at rest but developed an S₄ during isometric exercise. In this group, all but one patient had an abnormal left ventricular function curve. Finally, nine patients had an S₄ at rest as well as during isometric exercise. Seven of these patients had a normal left ventricular function curve. The results suggest that the development of an atrial gallop during isometric stress may be a more reliable indicator of left ventricular dysfunction than the presence of an S₄ at rest. Therefore, isometric exercise can be employed as a bedside procedure for evaluation of left ventricular function.