Saphenous veins in coronary artery bypass grafting need external support

Abstract

The saphenous vein is the most commonly used conduit for coronary artery bypass grafting. Arterial grafts are harvested with the outer pedicle intact whereas saphenous veins are harvested with the pedicle removed in the conventional graft harvesting technique. This conventional procedure causes considerable vascular damage. One strategy to improve vein graft patency has been to provide external support. Ongoing studies show that fitting a metal external support improves conventionally harvested saphenous vein graft patency. On the other hand, the no-touch technique of harvesting the saphenous vein provides an improved graft with long-term patency comparable to that of the internal mammary artery. This improvement is suggested to be due to preservation of vessel structures. Interestingly, many of the mechanisms proposed to be associated with the beneficial actions of an artificial external support on saphenous vein graft patency are similar to those underlying the beneficial effect of no-touch saphenous vein grafts where the intact outer layer acts as a natural support. Additional actions of external supports have been advocated, including promotion of angiogenesis, increased production of vascular-protective factors, and protection of endothelial cells. Using no-touch harvesting, normal vascular architecture is maintained, tissue and cell damage is minimized, and factors beneficial for graft patency are preserved. In this review, the significance of external support of saphenous vein grafts in coronary artery bypass grafting is discussed.

Towards Endoscopic No-Touch Saphenous Vein Graft Harvesting in Coronary Bypass Surgery

“…Since NO plays crucial roles in suppressing atherosclerosis, this mechanism may greatly contribute to the excellent patency in NT SVG. In addition to its vasoactive properties, PVAT also has a mechanical role in improving SVG performance where this external cushion not only protects the graft against the effects of increased coronary artery hemodynamics, but also provides support and prevents kinking in grafts of excessive length [ 26 , 27 , 50 , 51 ] . This natural property of PVAT appears not to have been considered, or has been overlooked, since there have been various strategies aimed at replacing the cushion of surrounding fat that is removed when using conventional OVH.…”

“…For example, this prominent outermost vessel layer not only prevents the SV from going into spasm at harvesting but also protects the endothelium against intraluminal pressures of 300 mmHg [ 8 , 9 ] . Various artificial methods of providing artificial support to conventional SVs have been studied, ranging from the use of a monofilament knitted tube [ 52 ] and fibrin glue [ 53 ] to “extents” made of Dacron [ 54 ] and of braided cobalt-chromium-nickel-molybdenum-iron alloy fibers [ 51 , 55 ] . The rationale for using external stents on damaged conventional SVG ranges from providing mechanical support to protection against the effect of arterial hemodynamics and the stimulation of angiogenesis [ 51 ] .…”

“…Various artificial methods of providing artificial support to conventional SVs have been studied, ranging from the use of a monofilament knitted tube [ 52 ] and fibrin glue [ 53 ] to “extents” made of Dacron [ 54 ] and of braided cobalt-chromium-nickel-molybdenum-iron alloy fibers [ 51 , 55 ] . The rationale for using external stents on damaged conventional SVG ranges from providing mechanical support to protection against the effect of arterial hemodynamics and the stimulation of angiogenesis [ 51 ] . One might question the reason for introducing such strategies that may be technically challenging, costly, and potentially harmful to patients undergoing CABG.…”

The Short-Term Patency Rate of a Saphenous Vein Bridge Using the No-Touch Technique in off-Pump Coronary Artery Bypass Grafting in Vein Harvesting

“…Samano et al 18 considered that the success of the no-touch technique involved many factors. When a GSV graft is obtained using the no-touch technique, the vascular wall is not touched directly by any instrument, and the adventitia and surrounding tissues are preserved, preventing the occurrence of venous spasm, avoiding pressurized expansion against venous spasm, and protecting the integrity of the vein endothelium and middle smooth muscle layer to the maximum extent.…”

Composite graft and remodeling of the saphenous vein in coronary artery bypass graft

“…Moreover, an inflammatory response resulting from the contact of the stent with the venous adventitious layer is described in the literature, with production of prostacyclin and reactive oxygen species, macrophage migration, and stimuli to the proliferation of the intimal layer. 2 , 3 …”