SVGs are indispensable to CABG surgery and provide diverse advantages including: emergent ease of access, shorter harvesting times, and sufficient length to bypass multiple distal coronary targets.2 Additionally, clinical factors (i.e., advanced age) or emergent surgical interventions (i.e., aortic root or valve surgery requiring conduit to bypass acutely occluded coronary arteries) highlight situations where SVGs are suitable and readily available for immediate harvesting.2 Vascular Injury and Barotrauma Clinical laboratory studies have demonstrated that damage to conduits during vessel harvesting and preparation influences both short and long-term patency.2,6 Traditional endoscopic vein harvesting (EVH) use of carbon dioxide (CO2) insufflation to maintain tunnel visualization has been shown to promote unfavorable local and systemic environments.10 The closed tunnel EVH permits passive systemic absorption of CO2, resulting in hypercarbia and tissue acidosis.10 The external pressurized CO2 (12-15 mmHg of insufflation) and endoscopic dissection further introduces extravascular stresses that could lead to detrimental changes in conduit integrity.10 Additionally, common SVG preparation consists of stripping vein conduits of its adventitial layer and vessel distention to overcome vascular spasms.6 The vascular manipulation and mechanical stress from these techniques can result in both intimal and luminal wall damage, predisposing the conduit to possible remodeling and accelerated intimal hyperplasia. 6,11 To avoid vascular insult, the development of “no-touch” saphenous vein harvesting was introduced.11 This technique involves harvesting a SVG pedicle (open harvesting, encompassing the saphenous vein and intact surrounding perivascular tissue), without direct vessel contact, which reduces vascular spasms and need for repeated pressure distention.11 The reduction of vascular distention decreases barotrauma and preserves luminal endothelium, retaining local nitric-oxide levels and slowing the development of intimal hyperplasia.2 Preservation of the perivascular tissue provides external structural support to prevent conduit kinking (preventing accelerated intimal hyperplasia and subsequent atherosclerosis) and retention of the vasa vasorum (retaining vessel wall perfusion and reduced ischemic damage).2 Perivascular adipose tissues anticontractile factors (i.e., nitric oxide, leptin) may also provide additional anti-spasmatic properties to preserve graft patency, which can significantly benefit patients with poor coronary anatomy (i.e., small coronary artery targets with poor distal runoff).2
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Journal of the Association of PAs in Cardiothoracic and Vascular Surgery
