Introduction
The traditional method of open vein harvesting (OVH) for coronary artery bypass grafting (CABG) with a single longitudinal incision on the lower extremity along the course of the greater saphenous vein (SV) has been historically associated with significant complications, including wound dehiscence, cellulitis, lymphangitis, drainage, edema, pain, hematomas, skin necrosis, and infection. These complications in turn lead to delayed wound healing, increased length of hospital stay, higher cost of postoperative care, and greater patient discomfort. Bitondo showed in 2002 that OVH is associated with about a 25% risk of leg-wound complications, creating an important clinical and economic burden . To reduce these complications, endoscopic vein harvest (EVH), a minimally invasive vein harvesting alternative, was first introduced clinically in 1996 . Encouraging short-term (≤6 months) clinical (less wound morbidity, less pain, better cosmetic results, and improved patient satisfaction) and graft patency outcomes were described , including a reduced the level of postoperative pain (pain score for EVH=0.52±0.95; OVH=1.02±1.51; P =.03) and wound complications (range from 3% to 7.4% for EVH and 13% to 19.4% for OVH) . These clinical benefits were associated with high levels of patient satisfaction.
Because the enthusiastic adoption of EVH in the clinical arena starting in the late 1900s preceded any professional consensus on this topic, in 2005 an Ad Hoc Committee of the International Society for Minimally Invasive Cardiothoracic Surgery (ISMICS) published a consensus statement on the use of EVH versus OVH in CABG , recommending that EVH be considered the “standard of care” (Class I, Level A) in order to reduce wound-related complications, improve patient satisfaction, and to decrease postop pain, length of hospital stay, and use of outpatient wound-management resources. However, the cardiac surgery community became alarmed when in July of 2009, Lopes and associates from the Duke Clinical Research Institute reported in the New England Journal of Medicine on the long-term follow-up results of a subgroup analysis of the Project of Ex-vivo Vein Graft Engineering via Transfection IV trial (PREVENT-IV) . The rate of vein-graft failure was significantly higher in those subjects enrolled in PREVENT-IV who underwent EVH [46.7% vs 38.0%; odds ratio 1.45, 95% confidence interval (CI) 1.20–1.76]. EVH was also associated with a significantly higher combined rate of mortality, myocardial infarction, and repeat revascularization 3 years after surgery (20.2% vs 17.4%; adjusted hazard ratio 1.22, 95% CI 1.01–1.47). The authors’ findings constituted the first published report in the literature of EVH being independently associated with vein-graft failure and adverse clinical outcomes. This paper also provided long-term follow-up data that contradicted accepted clinical practice and called into question the wisdom of the ISMICS recommendations. A meta-analysis of 102 studies (including Lopes), published in 2010, compared EVH to OVH in CABG . Results of this meta analysis showed that long-term graft patency in SVG harvested by OVH was better than those harvested by EVH (pooled odds ratio=1.25, P =.0039). The results of the influential PREVENT subanalysis led, in 2010, the Task Force on Myocardial Revascularization of the European Society of Cardiology and the European Association for Cardiothoracic Surgery to state in their updated Guidelines on Myocardial Revascularization that “EVH harvesting cannot be recommended at present as it has been associated with vein-graft failure and adverse clinical outcomes,” thus contradicting the 2005 ISMICS guideline and accepted clinical practice at the time .
The Randomized Endo-vein Graft Prospective trial
To provide a definite RCT comparing EVH and OVH and finally resolve this critical clinical dilemma regarding the safety of EVH, in 2010 we designed the Randomized Endo-vein Graft Prospective (REGROUP) trial, which was eventually funded in 2012 by the Cooperative Studies Program of the Department of Veterans Affairs . We identified in the importance of harvester experience in EVH the key factor that had not been adequately addressed in the literature with a proper and most importantly adequately powered randomized controlled trial. Proficiency in EVH requires a rather steep learning curve, and inexperienced operators may cause unnecessary stretching and trauma to the SV during harvest, leading to endothelial injury and possible early vein-graft failure. In order to participate as an SV harvester in REGROUP, each provider (e.g., physician assistant, nurse practitioner, or surgeon) submitted information on prior experience (certified by the respective site principal investigator) and had to receive approval to participate from an ad hoc REGROUP trial committee chaired by a senior physician assistant in the field of endoscopic harvest. Minimum expertise was defined as prior experience with >100 EVH cases with certified low (<5%) conversion rate to open harvest, as part of an established EVH program with >2 years of experience, as well as similar levels of experience with the open approach. The primary outcome was a composite of major adverse cardiac events (MACEs) during the active follow-up period, and the results were published in 2018 in the New England Journal of Medicine . In the REGROUP trial, we demonstrated equivalent rates of MACE between open and endoscopic vein-graft harvesting at a median follow-up of 2.78 years [MACEs occurred in 89 patients (15.5%) in the open-harvest group and 80 patients (13.9%) in the endoscopic-harvest group hazard ratio 1.12; 95% confidence interval, 0.83–1.51; P =.47], and longer follow-up results are expected in the summer of 2020. Furthermore, we observed a trend toward MACE risk reduction with the endoscopic technique when recurrent MACEs were compared, though longer term follow-up will be necessary to determine if this finding is persistent ( Fig. 8.1 ). Consistent with previous observations, endoscopic harvest resulted in better harvest site wound healing compared with the open approach: leg-wound infections occurred in 18 patients (3.1%) in the open-harvest group and in only 8 patients (1.4%) in the endoscopic-harvest group (absolute difference 1.7% points; relative risk 2.26, 95% CI, 0.99–5.15). There was no or little impact of incisional leg pain on patient’s functioning in 62.2% of patients in the open-harvest group compared with 79.1% in the endoscopic-harvest group at 6 weeks postoperatively (relative risk 0.77; 95% CI, 0.71–0.83). There was no significant difference in quality-of-life assessment between groups on either the VR-12 survey or the Seattle Angina Questionnaire. We believe that the EVH safety concerns raised in their 2009 report by the PREVENT-IV trial investigators may be explained by the lack of data on the experience of the endoscopic vein-graft harvesters in that study: by allowing less experienced harvesters to participate in PREVENT, it is possible that the quality of the conduits could have been compromised, contributing to accelerated vein-graft failure and worse clinical outcomes. Based on our findings of equivalent efficacy and better leg-wound healing in an appropriately powered multicenter randomized trial, EVH should be considered the first-choice technique for SV harvest by an experienced provider, and its indication should in our opinion be upgraded to Class IA.
Endoscopic vein harvest technique
The EVH procedure involves a small (~2.5–3 cm) incision above or below the knee and one to two smaller (~5 mm) incisions to divide and ligate the vein ( Fig. 8.2 ). The patient is positioned with hips slightly externally rotated allowing for access to the greater SV. Using landmarks on the leg, the placement of a skin incision is identified. If available, an ultrasound machine may be used to identify the location of the SV, its depth, and diameter ( Fig. 8.3 ) . Each EVH system utilizes an endoscopic approach in which the operator identifies the vein through a small incision, dissects the vein from the surrounding tissue, then seals, and divides the tributaries. The SV is then divided proximally and distally for removal.
There are four commercially available systems that are frequently utilized in the United States:
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VasoView (Getinge, Wayne, New Jersey): utilizing carbon dioxide insufflation, a conical tip on the end of an endoscope is used to dissect the vein. With a second instrument the surrounding tissue is divided, and the branches are sealed and divided using either the Hemopro (tip that seals and cuts) or Bisector (uses a bipolar energy source to seal and cut the tributaries).
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VirtuoSaph (Terumo): with a nonocclusive trocar, carbon dioxide insufflation is delivered near the conical tip used in dissection of the vein. A second instrument is used that secures the SV allowing for passage of an attached parallel device that coagulates and divides branches using a low energy source.
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VascuClear (LivaNova): this is an open carbon dioxide system that uses an instrument to create a tunnel over the SV. Another instrument is used that supports the tunnel so that a device can be inserted to seal and divide the tributaries using a bipolar device.
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Venapax (Saphena Medical): With carbon dioxide insufflation a single, conical tip device is used that dissects the vein and seals/divides the tributaries using a high-density, low-energy bipolar cautery. This system does not involve a separate component that supports or cradles the vein.
Optimal preoperative preparation includes vein mapping whenever possible . Plan the EVH procedure as having three separate stages: (1) choosing the incision site and making the incision, (2) dissecting the vessel and vessel tributaries, and (3) dividing the vessel branches.
Incision: decide on the best place to make the incision and mark the site, keep the length of the skin incision to a minimum, and consider making the incision to correspond with tension lines of the skin.
Heparin: an intravenous heparin bolus of a minimum of 1000 IU to a maximum of 5000 IU can be used at the beginning of the harvest .
CO 2 insufflation: use the lowest tunnel pressure possible to reduce the risk of CO 2 embolism, monitor central venous pressure, and use appropriate monitoring to be alerted to CO 2 -related events . The trocar cuff should be kept deflated to avoid interruption of blood flow inside the SV.
Dissection of the vessel: establish a regular sequence of dissection; use short, gentle motions; ensure that side branches are thoroughly dissected to allow adequate length during branch division; and apply appropriate pressure with the opposing hand to promote ease of dissection along the vessel.
Division of branches: establish a regular sequence for dividing the branches, consider making a fasciotomy along the tunnel if the space is very tight, before dividing the branch consider whether it is of adequate length to clip or tie, keep energy settings as low as possible during branch division ( Fig. 8.4A and B ).
