Cardiac function assessed by systolic time intervals after aortocoronary saphenous vein bypass surgery.

Systolic time intervals were measured in 33 patients undergoing aortocoronary saphenous vein bypass, before operation and 7 days after operation. Eighteen patients had normal systolic time intervals before operation (group I), and I5 had abnormal preoperative intervals (group II). Group I patients experienced significant shortening of the left ventricular ejection time index from 404 msec to 371 msec postoperatively (P< o ooi), with no significant change in the pre-ejection phase index. These changes are consistent with acute left ventricu- lar dysfunction in the early postoperative period. Group II patients had an entirely different response, with no significant change in the postoperative left ventricular ejection time index and a significant decrease in the pre-ejection phase index from I55 msec to I43 msec (P< o.ooI). The shortening of pre-ejection phase index may have represented improved ventrticular function after operation. An alternative explanation for pre-ejection phase index shortening would be the effects of adrenergic stimulation. Later observations at I to 2 months suggested that the group I response was transient and the group II response was sustained.