**8. The future of prevention: from the research bench to the operating room**

Much interest in reducing neointimal hyperplasia by blocking gene expression is arising. The cell cycle of endothelial cells is now better understood and therefore has allowed for genetics to help play a role in preventing stenosis, thrombosis, and ischemia. If the genetic pathways that are associated with the above process can be fully identified this may ultimately influence coronary graft patency. Ex-vivo work has been promising to show that blocking of the cell cycle via gene therapy has slowed down the atherosclerosis that can lead to graft failure [1].

Repeat coronary vascular procedures will continue to be problematic until an understanding of the mechanisms of vein graft have been elucidated. Thus far, extensive research has been done on this topic, but an overall consensus exists that the saphenous vein is a very fragile and easily injured conduit. Great care must be taken while handling the vein during harvest and preparation to avoid damage or stress to either the external or internal surface of the vein. Avoiding supra-physiologic pressure, prolonged distention periods and manipulations which result in tissue inflammation and injury should be employed to prevent graft failure. Such efforts are expected to reduce the morbidity associated with saphenous vein graft disease and repeat coronary artery bypass interventions.

1 Department of Anesthesiology, University of Nebraska Medical Center, Omaha, Nebraska,

Saphenous Vein Conduit in Coronary Artery Bypass Surgery — Patency Rates and Proposed Mechanisms for Failure

http://dx.doi.org/10.5772/55098

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2 Experimental Immunology Laboratory, Research in Autoimmune Disease, Division of Rheumatology and Immunology, Department of Internal Medicine, University of Nebraska

3 Experimental Immunology Laboratory, Research in Cardiovascular Disease, Division of

4 Department of Pathology and Microbiology, University of Nebraska Medical Center,

6 Department of Surgery, Division of Cardiac Surgery, Maui Memorial Medical Center, Wai‐

[1] Shuhaiber, J. H, Evans, A. N, Massad, M. G, & Geha, A. S. Mechanisms and future directions for prevention of vein graft failure in coronary bypass surgery. Eur J Car‐

[2] Khaleel, M. S, Dorheim, T. A, & Duryee, M. J. High-Pressure Distention of the Saphe‐ nous Vein During Preparation Results in Increased Markers of Inflammation: A Po‐

[3] Favaloro, R. Saphenous Vein Autograft Replacement of Severe Segmental Coronary Artery Occlusion: Operative Technique. Ann Thorac Surg. (1968). , 5, 334-339.

[4] Lopes, R. D, Hafley, G. E, Allen, K. B, et al. Endoscopic versus Open Vein-Graft Har‐ vesting in Coronary-Artery Bypass Surgery. New Eng Jour Med. (2009). , 361,

[5] Bonde, P, & Graham, A. N. MacGowan SW. Endoscopic vein harvest: advantages

[6] Black, E. A, Campbell, R. K, Channon, K. M, Ratnatunga, C, & Pillai, R. Minimally invasive vein harvesting significantly reduces pain and wound morbidity. Eur J Car‐

[7] Ramos, J. R, Berger, K, Mansfield, P. B, & Sauvage, L. R. Histologic Fate and Endo‐ thelial Changes of Distended and Nondistended Vein Grafts. Ann Surg. (1976). [8] Souza DSRJohansson B, Bojo L, et al. Harvesting the Saphenous vein with the sur‐ rounding tissue for CABG provides Long-Term Graft Patency comparable to the Left

tential Mechanism for Graft Failure. Ann Thorac Surg (2012). , 93, 552-8.

Cardiology, University of Nebraska Medical Center, Omaha, Nebraska, USA

5 Omaha VA Medical Center, Research Services 151, Omaha, Nebraska, USA

diothorac Surg. (2002). Sep;Review., 22(3), 387-96.

and limitations. Ann Thorac Surg (2004). , 77, 2076-82.

diothorac Surg (2002). , 22, 381-6.

USA

Medical Center, Omaha, Nebraska, USA

Omaha, Nebraska, USA

luku Hawaii, USA

235-244.

**References**

**Figure 1.** Scanning electron microscopy photomicrographs of vein tissue following harvest and distention. Saphenous veins underwent endoscopic harvest during bypass grafting procedures with routine pressure distention to ligate side branches. Vein distention was performed by attaching a syringe to the most anatomically distal portion of the vein. A segment of vein was obtained prior to distention and several segments along the length of the vein were harvested after distention and subjected to scanning electron microscopy. Pictures shown in the figure are (A) non-distended vein (B) most distal portion of vein from origin of distention (C) mid section of saphenous vein graft (D) vein segment closest to the syringe. Shown in the pictures are endothelial layer starting to change from a smooth flat surface to a rounded up rough surface.
