Effects of Occlusion Devices for Minimally Invasive Coronary Artery Bypass Surgery on Coronary Endothelial Function of Atherosclerotic Arteries
Abstract
Background: During minimally invasive coronary artery bypass grafting surgery, technical devices are required to obtain an optimal operative field. However, these devices can cause lesions to the endothelium. Previous studies of the effect of devices on coronary endothelial function have been performed on normal coronary arteries. Balloon denudation is followed by regeneration of the endothelium, which is dysfunctional and by intimal hyperplasia resembling atherosclerosis. The Anastaflo™ (Baxter, Mississauga, Ontario, Canada) shunt is a surgical device used during the performance of coronary anastomoses that allows a continuous flow inside the artery during the surgery.
Methods: We compared the effects of three commonly used techniques on endothelial function: 1) using the Anastaflo™ shunt, 2) using Retract-o-tape® (Genzyme, Cambridge, MA) silicone air cushion snaring, and 3) using a bulldog clamp on arteries submitted to balloon denudation 30 days prior to the surgical experiment on an in vivo model of beating heart off-pump coronary artery bypass (OPCAB). Balloon denudation was performed on the left anterior descending artery and on the right coronary artery.The devices were applied for 15 minutes on porcine epicardial coronary arteries, on the beating heart, after median sternotomy. Denuded control rings were taken at the site of denudation on which no devices were applied while non-denuded control rings were taken from the left circumflex artery. The endothelial function of control and instrumented arterial rings was studied in organ chambers filled with a modified Krebs-Ringer bicarbonate solution. After contraction to prostaglandin F2α, endothelium-dependent relaxation to serotonin (an agonist coupled to Gi-proteins) and bradykinin (a non–Gi-protein coupled agonist) were compared in the shunting group, the snaring group, the clamping group, and in controls.
Results: There was a significant decrease in the relax-ations to serotonin and bradykinin in the denuded control group compared with the non-denuded control group, confirming that balloon denudation caused an endothelial dysfunction. However, there was no significant difference between the denuded control group and the hemostatic device groups (shunting, snaring and clamping) in the relaxation to serotonin.
Conclusion: These results suggest that hemostatic devices used for OPCAB do not cause any greater injury in atherosclerotic coronary arteries already harbouring an endothelial dysfunction. The effects on platelet aggregation, intimal dissection, and plaque rupture remain to be determined.
