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Ann Thorac Surg 1999;68:1513-1516
© 1999 The Society of Thoracic Surgeons
a Cardiovascular Surgery Associates SC, St. Luke’s Medical Center, Milwaukee, Wisconsin, USA
Address reprint requests to Dr Crouch, Cardiovascular Surgery Associates SC, 2901 W Kinnickinnic River Pkwy, Suite 310, Milwaukee, WI 53215
e-mail: jcrouch{at}execpc.com
Presented at Evolving Techniques and Technologies in Minimally Invasive Cardiac Surgery, San Antonio, TX Jan 22–23, 1999.
Abstract
Background. The saphenous vein is an important conduit for coronary artery bypass grafting. Wound complications from traditional open vein harvesting occur often. Minimally invasive endoscopic saphenous vein harvesting may decrease wound complications. Vein quality may be an issue with endoscopic harvesting.
Methods. We reviewed 568 patients who had bypass grafting and saphenous vein harvesting either endoscopic (group A, n = 180) versus open (group B, n = 388). Both groups were demographically similar and management identical. Wound complication was defined by the need for intervention and included lymphocele, hematoma, cellulitis, edema, eschar, and infection. Multiple vein segments were obtained from 8 patients, 4 from each group, and examined histologically.
Results. Wound complications were significantly less in group A (9/180, 5%) versus group B (55/388, 14.2%), p value equal to or less than 0.001. Open harvesting (p 
0.001), diabetes (p 0.001), and obesity (p 0.02) were risk factors for wound complication by univariate analysis. By multiple logistic analysis, open harvesting (p 0.0007) and diabetes (p 0.0001) were independent risk factors for wound infection. Histologic evaluation of vein samples showed that there was no difference between the groups and vascular structural integrity was maintained.
Conclusions. Endoscopic saphenous vein harvesting was associated with fewer wound complications and infections. Vein quality was not adversely effected because of endoscopic harvesting.
The saphenous vein remains an essential conduit for coronary artery bypass grafting. Saphenous vein harvesting is customarily performed through a longitudinal lower extremity incision. This open technique, despite meticulous attention, can result in wound complications. Depending upon the definition and severity of these complications, reports indicate that wound complications may occur in 20% to 40% of patients [1, 2]. Newer techniques utilizing minimally invasive endoscopic harvesting have been reported [3–6]. These initial reports show reduction in wound complications and excellent healing. However, before there is general acceptance of these newer endoscopic techniques, they must also show that saphenous vein quality has not been impaired. Previous reports looking at saphenous vein histology after endoscopic harvesting have yet to be published. This retrospective study compares outcomes in traditional open saphenous vein harvesting with endoscopic saphenous vein harvesting (ESVH), including a histologic comparison.
Patients and methods
From October 1997 to May 1998, 568 consecutive patients had bypass surgery requiring saphenous vein grafts. These patients were divided into two groups. Patients in group A (n = 180) had endoscopic saphenous vein harvesting. Patients in group B (n = 388) had traditional open saphenous harvesting. All deaths were excluded. There were 13 conversions from ESVH to open technique. Decisions regarding the use of open technique or ESVH technique were based on operating surgeon’s preference. Physician assistants in all cases performed the vein harvesting. There was follow-up in all patients. Postoperative care, including perioperative antibiotics and wound care, was identical for both groups. Cefazolin was used perioperatively 24 hours or when the chest tubes were removed. Vancomycin was substituted if the patients were allergic to cefazolin.
Wounds were cleaned with soap and water daily and dressings applied only for drainage.
Wounds were examined daily in the hospital and at discharge. Patients were then seen postoperatively at 4 to 6 weeks after discharge or more often if necessary. Wound healing was considered a complication if intervention was required. These interventions included additional wound care, antibiotics, wound debridement, readmission, and surgical repair or revascularization. Wound complications included lymphocele, hematoma, infection, eschar, cellulitis, dehiscence, or drainage. Wound assessment was made by surgeon, internist, or nurse.
Saphenous vein segments harvested from 8 patients were analyzed. Four patients were from group A (ESVH) and four patients were from group B (open harvest). Sections were taken at branch points as well as midportions of the veins. The veins were studied by light microscopy at x200 magnification by an independent pathologist. Vein segments were stained with standard immunoperioxidase techniques for CD31, Factor VIII, and vimentin to evaluate the integrity of the endothelium. Hematoxylin and eosin (H&E) staining was also performed to evaluate the histology of the intima, adventitia, the vasovasorum, and to assess for coagulation injury.
Operative technique: endoscopic
Group A patients had ESVH performed using the VasoView system (Guidant, Cardiac and Vascular Surgery, Inc, Menlo Park, CA). This unique system uses CO2 to enable dissection and visualization. Physician assistants performed the harvesting in every case. The technique used has been described previously [7]. There was no preoperative vein mapping, and the selection of extremity was determined by presence of previous surgery as well as the quality of skin and tissue. Patient preparation was identical to open harvesting with circumferential prep. The operating setup was also similar, except for the endoscopic equipment and video tower.
Dependent upon the length of vein required, the harvesting begins medially either above or below the knee with a single small incision 1.5 to 2.5 cm in length. It was attempted to avoid making the incision across the knee flexion area. Harvesting is initially directed toward the groin region as far proximally as required for adequate vein length. Once the vein is isolated circumferentially, the side branches are divided using bipolar cauterizing scissors. A small puncture incision is made under endoscopic vision proximally, directly over the saphenous vein to clamp, ligate, and divide the vein for removal and preparation. The side branches are then ligated and repairs are made, if necessary, with 7-0 monofilament Prolene suture. If additional length of vein is required, the endoscopic dissection is directed down the leg distally. Usually, two to three segments of saphenous vein, each approximately 15 cm in length, can be harvested with a single incision.
The leg wound is carefully inspected for any bleeding, but is not closed until after the heparin has been reversed. The harvest site is gently massaged to express any blood or clots, and is then closed with absorbable subcutaneous and subcuticular sutures. No drains are used, but the legs are wrapped with an elastic ace wrap and left on for 48 hours.
Operative technique: open
Group B patients had open traditional vein harvesting. Physician assistants performed harvesting. A long incision was made over the saphenous vein and the length was dependent upon the number of vein grafts required. Once the vein was exposed, the side branches were ligated or clipped on both the patient side and the graft side. Cautery was not used to divide vein branches. The vein was then removed and prepared. The open leg wound is then checked for hemostasis and irrigated with saline solution. Closure of the incision was then performed in layers with absorbable suture and completed with a subcuticular closure. At the end of the operation, the leg wound is covered with a cotton gauze dressing and an elastic ace wrap is applied to the entire leg, which is removed in 48 hours.
Statistical analysis
Data were analyzed with the SAS System (SAS Institute, Cary, NC) software package. Student’s t test was used for statistical analysis of continuous variables. 
2 analysis was performed on categorical variables. Multiple logistical regression analysis was used to compare independent risk factors for wound complications. Mantel-Haenszel analysis was used to determine relative risk for wound complication comparing ESVH versus open harvesting, adjusted for diabetes and obesity. Statistical significance was determined at a p value equal to or less than 0.05.
Results
Patient characteristics are summarized in Table 1. The mean age of group A patients was slightly younger (64.9 ± 10.6 vs 67.1 ± 10.9) than group B. In addition, the group A patients were more obese (body mass index [BMI]: female > 34, male > 32) than the group B patients (28.3% vs 20.4%, p 0.03). Otherwise, the groups were similar for gender ratio, body surface area (BSA), BMI, diabetes, and peripheral vascular disease. Operative data for both groups were also similar (Table 2). The mean number of vein grafts was slightly more in the ESVH group A patients (2.3 ± 0.7 vs 2.2 ± 0.9, p 0.30). Arterial grafts were used with similar frequency in both groups A and B, respectively (91.1% vs 86.3%, p 0.10). Redo operations or combined operations with valve surgery were not significantly different (group A vs group B, 6.7% vs 11.3%, p 0.082; 15% vs 20.9%, p 0.10), respectively. There were 13 patients who had conversions from endoscopic to open harvesting. The reasons for converting was secondary to poor vein quality or additional vein being needed during the operation. The length of stay (LOS) was shorter for the ESVH group A patients than in the open group B (7.63 ± 6.05 vs 8.71 ± 7.52, p 0.08).
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0.001). Antibiotic usage, both inpatient (6.2% vs 1.1%, p 0.003) as well as outpatient (11.6% vs 3.3%, p 0.007), was more common in the group B patients. Wound debridement was necessary in 11 of 55 (20%) group B patients and 0 of 9 ESVH patients (p 
0.3). Readmission for wound complications occurred in 9 of 55 (16%) for group B and 0 of 9 in the group A (p 0.3). In 3 of the readmissions in group B, 2 required peripheral vascular operations and 1 required skin grafting by plastic surgery.
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0.001), diabetes (p 0.001), and obesity (p 0.03) were significant risk factors for wound complications. Multiple logistic regression analysis was applied to risk factors for wound complication (Table 5). Diabetes and open harvesting were independent predictors for wound complications. When adjusted for obesity and diabetes, open harvesting had 3.05 greater risk for wound complications than ESVH (p 0.01).
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Comment
The saphenous vein grafts are used in over 95% of all coronary artery bypass cases. The open harvesting technique has generally remained unchanged despite the morbidity associated with this procedure. Minimally invasive endoscopic surgery has revolutionized many different fields of surgery. These techniques have allowed operations to be performed with less morbidity in most patients. ESVH has been developed consistent with this pursuit for less invasive technique and morbid results. Early reports indicate that endoscopic saphenous vein harvesting is technically feasible and is associated with better wound outcomes [6].
In order for endoscopic saphenous vein harvesting to be generally accepted, it must not significantly prolong or delay the operation. Although not specifically addressed in this study, we previously reported that endoscopic saphenous vein harvesting with the Vasoview system had an acceptable learning curve [7]. In addition, harvest times of at least 1.0 cm/min or better could be expected. This would mean that 30 to 45 minutes might be expected to obtain two to three segments of vein for grafting. This would compare favorably with other endoscopic techniques [5, 6]. When considering total time for open harvesting and closure for the long incision, the time difference may be quite similar.
Leg wound complications after open harvesting in patients with bypass grafting have received very little emphasis despite the potential for serious morbidity. The cause of wound complications, and more importantly infections, is not completely understood. However, tissue trauma, exposure, and wound closure methods likely play a role. An advantage of the endoscopic method is the reduction in these factors. The subjective interpretation of wound complications may account for the wide variance reported in the literature. For this study, we interpreted a wound complication as significant if intervention necessitating extra care was required. Our complication incidence of 5% in the ESVH group was significantly lower then the 14.2% incidence in the open harvesting group. Allen and associates reported a similar wound complication incidence using a different endoscopic technique [4].
Obesity, diabetes, female gender, and peripheral vascular disease have previously been reported as risk factors for wound complication [8]. In this study, obesity and diabetes were also found to be significant, as well as the technique in vein harvesting. Only open harvesting and diabetes were independent risk factors for developing wound complications. In fact, our analysis reveals that ESVH may minimize the effect of both diabetes and obesity on the incidence of wound complications.
Preservation of the endothelium is an important factor in long-term patency of saphenous vein grafts [9]. Damage may occur during the harvesting process by mechanical trauma as well as thermal injury from cauterization. The concern for increased saphenous vein trauma with ESVH is an issue that has not been directly addressed. Other reports have looked at acute patency as an extrapolation to vein intimal integrity. In our limited study, with only 8 patients represented, there was no difference histologically in vein specimens from either harvesting method. Using four different staining methods, endothelium and vein ultrastructure were intact. Because of the use of cautery in the ESVH technique, there is concern regarding coagulation effect. Unlike unipolar cautery, bipolar cauterization, similar to that used in this ESVH system, has been shown to produce less scattering of thermal injury [10]. There was no direct histologic evidence for cautery damage by hemotoxylin:eosin. We feel that the safety of this ESVH technique is apparent, but longer outcome studies are required including electron microscopy.
The additional costs associated with ESVH are clearly an issue. This study showed that wound complications were reduced by at least 60% by using ESVH. The costs associated with treatment of wound complication are the result of additional admissions, office visits, wound care, debridement, and antibiotic use. All of these interventions were more common in the open harvesting group. Extrapolating this 60% reduction in wound complications, a potential reduction in cost could be realized by using ESVH. The reported costs in treating wound complications have not been extensively studied. However, one study reported a conservative estimate for the inpatient cost of treating each wound complication was approximately $9,000 [2]. Previous studies have shown an apparent reduction in hospital LOS inpatients who have had ESVH [4, 5]. We found a similar decrease in the LOS. This may be an additional important cost saving. More extensive cost studies are in progress.
In conclusion, we have shown that ESVH significantly reduces wound complications. This was evident by less readmissions, antibiotics, office visits, wound care, and surgical procedures. Early histologic evaluation shows no detrimental effect on the vein.
Acknowledgments
An educational grant for this study was provided by Guidant, Cardiac and Vascular Surgery, Inc, Menlo Park, CA.
References
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