Effect of coronary occlusion on left ventricular function with and withoutcollateral supply during beating heart coronary artery surgery

Objective-To study the effects of coronary occlusion and collateral supply on left ventricular (LV) function during beating heart coronary artery surg ery. Design-Prospective intraoperative study, performed at baseline, during wall stabilisation, coronary artery occlusion, and 2 and 10 minutes after reper fusion. Transoesophageal M mode echocardiograms, simultaneous high fidelity LV pressure, and thermodilution cardiac output were measured. LV anterior wall thickening, thinning velocities, thickening fraction, regional work, a nd power production were derived. Asynchrony during the isovolumic periods was quantified as cycle efficiency. Setting-Tertiary referral cardiac centre. Patients-14 patients with stable angina, mean (SD) age 62 (7) years, underg oing left anterior descending artery grafting using the "Octopus" device. Results-Collaterals were absent in nine patients and present in five. Epica rdial stabilisation did not affect LV function. Results are expressed as me an (SD). Coronary occlusion (15.6 (2) minutes) depressed anterior wall thic kening (1.4 (0.6) v 2.6 (0.6) cm/s) and thinning velocities (1.4 (0.5) v 3. 0 (0.6) cm/s), regional work (2.2 (0.8) v 4.6 (0.6) mJ/cm(2)), and power (2 1 (4) v 33 (5) mW/cm(2)) in patients without collaterals (p < 0.05 for all) , but only wall thinning (3.5 (0.5) v 4.8 (0.5) cm/s, p < 0.05) in patients with collaterals. All returned to baseline within 10 minutes of reperfusio n. Cycle efficiency and regional work were impaired at baseline and fell du ring occlusion, regardless of collaterals. Within 10 minutes of reperfusion both had increased above baseline. Conclusions-Coronary occlusion for up to 15 minutes during beating heart co ronary artery surgery depressed standard measurements of systolic and diast olic anterior wall function in patients without collaterals, but only those of diastolic function in patients with collaterals. Regional synchrony dec reased in both groups. All disturbances regressed within 10 minutes of repe rfusion.