Left ventricular function following coronary bypass surgery.

The effect of coronary artery bypass grafts on left ventricular performance was evaluated by analyzing preoperative (preop) and postoperative (postop) biplane left ventriculograms of 37 patients who were restudied at a mean of 13 months after operation. Eighty-two percent of the grafts were patent. Segmental wall shortening and segmental shortening velocities (mea Vcf) in the anterior, inferior and lateral regions of the left ventricle were compared in four groups: 1) regions with patent grafts and normal preop shortening, 2) regions with patent grafts and preop asynergy, 3) regions with occluded grafts and 4) ungrafted regions. In the 38 regions with preop normal shortening and patent grafts, shortening and shortening velocities were unchanged postop. In the 13 regions with preop asynergy and patent grafts, % shortening increased 22 + 8 (P < 0.01) and mean Vd, increased 0.82 ± 34 lengths/sec, (P < 0.025). In the 13 regions with occluded grafts, % shortening decreased 6 ± 3 (P < 0.05) and mean Vcf decreased 0.24 ± 0.11 lengths/sec (P < 0.025). In the 28 regions which were ungrafted, there was no change in shortening, while mean V,r decreased 0.56 ± 0.22 lengths/sec (P < 0.025). The effect of bypass grafts on global ventricular performance as measured by the ejection fraction (EF) was examined in patients with all patent grafts and normal preop wall motion, patients with all patent grafts and preop asynergy, patients with one or more occluded grafts and all patients combined. In the 11 patients with all patent grafts and normal preop wall motion, the EF was unchanged (0.74 0.03 preop and 0.71 0.02 postop; P = NS), while the EF increased in the 11 patients with all patent grafts and preop asynergy (0.53 ± 0.02 preop and 0.65 ± 0.05 postop; P < 0.05). In the 11 patients with one or more occluded grafts, the EF decreased (0.67 ± 0.04 preop and 0.57 ± 0.03 postop; P < 0.05). The mean EF did not change in the entire group (0.65 ± 0.02 preop and 0.64 ± 0.02 postop; P = NS). We conclude that patent coronary artery bypass grafts are associated with maintenance of myocardial function in patients with normal preop ventricular function. In patients with depressed ventricular performance, patent grafts result in improvement of regional and global function while occluded grafts result in depression of regional and global performance.