Discussion
GSV remains the most common conduit for CABG, which is the most common operation in cardiac surgery. Multiple studies in the literature have examined surgical site infection (SSI) after GSV harvested, and these show advantage of EVH (3%-13%) vs. OVH (12%-43%)[7] .The incidence of infection is (20%) in OVH group without any recorded infection in EVH group in our study.
Preoperative risk factors normally associated with leg wound complications include female gender, DM, obesity, hypoalbuminemia, anemia, PVD, chronic ischemia and steroid use. OVH technique has more severe infections involving larger areas of the wound. However, tissue trauma and wound closure methods likely play a role. EVH may minimize the effect of both diabetes and obesity on the incidence of wound complications. The fact that only thigh veins are harvested in EVH group might reduce the wound complications as diabetic vasculopathy being largely a small vessel disease would affect wound healing more below the knees. OVH technique in the thigh was found to be the only risk[3] .The risk factors are similar in both groups of our study. In Our study, EVH is mainly from thigh, however, 10% from leg and 30% extended from the whole lower limb. The site of harvesting did not affect rate of infection. Also, there is high rate of infection in diabetic patients 22% more than non-diabetic 9%.
Compared with OVH, EVH using the back-approach technique was associated with satisfactory short-term results. EVH was associated with lower rates of leg wound complications and a shorter length of hospitalization[8] . Total hospital stay for EVH group was (5.5 ± 2.4 days) vs. OVH group was (9.5 ± 2.7 days).
Extended EVH offers significant advantages over OVH and with experience a surgeon can safely perform EVH in shorter time. The results using this technique are superior to OVH or combined (EVH in thigh and OVH in leg) techniques. By avoiding wound complications minimally invasive techniques for vein harvest may reduce postoperative morbidity, and hospital stay [4] . Learning curve of EVH is growing; we started with 70min. until reached 40min. In cases of combined technique or conversion of EVH to OVH, we exclude cases from study. We harvested by extended technique in thigh and leg within reasonable time, and provided long vein graft for multiple conduits in (15) cases.
Traditional OVH may increase post operation wound complications. These wounds and their complications can influence the patient’s physical activity and may make limitations of mobility, so it is very harmful in post CABG rehabilitation therapy [9] . As, we know that physiotherapy and early mobilization after CABG is very important for convalescence, EVH has significant early mobilization over OVH (P value 0.02)
EVH has been shown to be safe and reproducible with low incidence of leg complications. Patients are satisfied by small incision and absence of leg wound discomfort. As the experience grows, learning curve is required to become familiar with EVH [2] . Postoperative leg pain, mobilization, and overall patient satisfaction were also significantly improved in study EVH group.
There is widespread general acceptance of EVH doubts about its impact on the integrity, quality of the conduit and longterm graft patency[3] . EVH has emerged as minimally invasive technique that reduces wound pain and infection in CABG surgery. In a histological and immunohistochemical evaluation of SVG, EVH showed superiority in endothelial layer preservation when compared to OVH [10] . We take EVH as a step for MIDCAB. We did not perform vein endoscopy after EVH or coronary angiography during follow up period, however, coronary Flowmeter was done in all cases without any difference between both groups.
CABG is a commonly performed open heart surgery worldwide, and GSV is used as a conduit for bypass in over 95% cases. The OVH technique has remained unchanged over the years. However, leg wound complications can be a major source of postoperative morbidity [11] . The best indication for EVH is the patients with increased risk for wound infection and in whom cosmetics is a major concern. EVH should be the standard in all cases of GSV harvesting.
Cost may be an important consideration when choosing an endoscopic approach to harvesting GSV. Each endoscopic procedure has a definite added cost due to the expense of the disposable equipment required along with an initial investment in the non-disposable equipment (monitor, camera, light source, and CO2 insufflator). However, overall savings based on improved wound healing and, therefore, fewer additional treatments may counter balance the added cost of the equipment[12] .The cost of EVH is already more than OVH, however, cost of long time hospital stay, readmissions, needed other surgical procedure and antibiotics have a cost loaded on health system. We needed large number of patients to compare cost effect of both techniques.
Another consideration is the time it takes to learn and master this technique. The time it takes to become fully adept at this technique varies and is operator dependent. By logistic regression analysis, the only significant of impaired wound healing was open vein harvesting[12] . We finished training course until reaching reasonable time of EVH to start the study, so EVH has significant less leg wound complications vs. OVH (P value 0.03)
EVH reduces the incidence of postoperative leg wound complications, especially leg wound infections. Moreover, there are significant differences in the patients’ postoperative mobility, leg pain, and satisfaction, favoring EVH. Therefore, the recommendation is routine use of EVH in CABG [13] . During the last decade, surgery has been moved towards less invasive access and to minimizing length of incision [14]. In EVH group, patients were very satisfied with leg wound (99%), and had significant less pain and more cosmesis (P value 0.02) vs. OVH group.