Elsevier

The Annals of Thoracic Surgery

Volume 72, Issue 6, December 2001, Pages S2245-S2252
The Annals of Thoracic Surgery

The coronary artery bypass conduit: I. Intraoperative endothelial injury and its implication on graft patency

Presented at Monitoring and Improving Patient Safety During and Following Cardiac Surgery, San Diego, CA, May 5, 2001.
https://doi.org/10.1016/S0003-4975(01)03272-6Get rights and content

Abstract

Prevention of intraoperative injury to the vascular endothelium is of primary importance in maintaining viability and patency of the aorto-coronary saphenous vein graft. Surgical manipulation, ischemia, storage conditions, and distension before anastomosis can abnormally alter the antithrombogenic property of the endothelium leading to vasospasms, thrombogenesis, occlusive intimal hyperplasia, and stenosis. Endothelial injury can also form an initiation site for the formation of later-stage atheromas and graft failure. A multifactorial strategy aimed at prevention of endothelial injury and graft failure should include improved surgical techniques, optimal preservation conditions, avoidance of nonphysiologic distension pressures, and use of specific pharmacologic agents as the primary form of intervention. The successful application of this strategy, and the development of newer and more efficacious strategies that may impact on long-term graft patency, can now be aided by assessment of the structural and functional integrity of bypass conduits using multiphoton imaging techniques.

Section snippets

Stage 1: thrombogenesis

Venous graft failure within 1 month after CABG surgery is thought to occur as a result of thrombogenesis 1, 2, 3, 4, 5, 6, 7, 8, 9, 11. Early pathologic changes observed in autogenous saphenous vein grafts implanted as arterial autografts include acute thrombosis, denudation of endothelium, platelet and fibrin accumulation, cellular intimal subendothelial infiltrates, myointimal proliferation, smooth muscle necrosis, and inflammation 1, 2, 3, 4, 5, 6, 7, 8, 9.

Endothelial cells are known to be

Measuremnt of endothelial function

The intraoperative preservation of harvested saphenous veins before performance of coronary artery bypass grafting is a factor in the protection of the endothelial cells. Short-term preservation of free vascular grafts is a daily routine in coronary operations, in which 1 to 2 hours may elapse between harvesting and reperfusion. This interval may affect both the structure and function of the graft, depending upon the composition of the storage solution, the storage temperature, or the duration

Structural assessment

The structural and functional viability of vessel endothelium is measured with a fluorescence-based, super-vitality, live–dead assay [24]. This assay measures the structural integrity of cells by allowing the membrane-permeable calcein AM ester dye to enter the cell and be transformed by the cellular esterases to produce green fluorescence in living cells, thus providing a measure of enzyme activity and cell viability. In contrast, the membrane impermeable ethidium homodimer enters compromised

Summary

Endothelial dysfunction is the primary determinant in the interrelated pathogenesis of thrombosis, intimal hyperplasia, and arteriosclerosis in aorto-coronary saphenous vein graft failure. The plethora of risk factors that can cause endothelial abnormalities and graft failure include (but are not restricted to) surgical trauma, ischemia, storage conditions, distension, and arterialization of venous grafts. Inherent deficiencies of the vein as a bypass conduit, structural and functional damage

Acknowledgements

We thank Vaidya (Dr.) Ajit S. Kolatkar for sharing his knowledge of blood circulation and useful discussions. HST acknowledges Aditi Thatte for her encouragement and support. The editorial assistance of Mrs. Nancy Healey is greatly appreciated.

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