[Pre- and postoperative left ventricular function. After aortocoronary bypass surgery].
The effect of coronary artery bypass graft (CBG) on left ventricular performance was evaluated by analysing preoperative (preop) and postoperative (postop) pressure-derived measurements from tip manometers during atrial pacing stress (APS) and resting segmental wall motion (SWM) of 50 patients (pts), restudied 12 months after CBG. Preoperatively, graft flow and reactive hyperemia (RH) were also measured. End diastolic pressure (EDP) maximal velocity of contractile element (Vmax) during APS, mean velocity of circumferential fiber shortening (Vcf) and SWM at rest were compared in three groups: Gr I, 13 pts with postop increase (+5 p. 100) of ejection fraction (EF); Gr II, 16 pts with EF decreased (-5 p. 100); Gr III, 21 pts with EF unchanged (+/- 4 p. 100). At rest, EDP of Gr II was the only parameter significantly altered with a postop increase of 5 mmHg (< 0.05). During APS, Vmax postop is increased in Gr I (59.5 s-1 preop, 67.5 postop, p < 0.02) while it is decreased in Gr II (67 s-1 preop, 57 postop, p < 0.05) and unchanged in Gr III. At rest, consistent changes in mean Vcf were found in Gr I (0.69 length/s preop, 0.97 postop, p < 0.001) and Gr II (0.87 preop, 0.68 postop, p < 0.001). In Gr I, regional improvement in wall motion was equally distributed to the anterior and posterior wall. In Gr II postop reduction of regional shortening was confined to the anterior wall. In Gr II successful revascularization of the anterior wall was performed only in 55 p. 100 of pts versus p. 100 in Gr I. In addition, during RH, peak diastolic flow was significantly higher (p < 0.05) in Gr I (341 +/- 63 ml) than in Gr II (197 +/- 34) underlining the higher level of effective revascularization attained in GrI. We conclude that resting regional and global ejection phase indices as well isovolumic phase indices during stress will improve when complete revascularization procedure is successful.