The saphenous vein is routinely dissected in an open. Minimally Invasive Saphenous Vein Harvesting Techniques: Morphology and Postoperative Outcome

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1 Minimally Invasive Saphenous Vein Harvesting Techniques: Morphology and Postoperative Outcome Alexander M. Fabricius, MD, Anno Diegeler, MD, PhD, Nicolas Doll, MD, Horst Weidenbach, MD, and Friedrich W. Mohr, MD, PhD Klinik für Herzchirurgie, Division of Pathology, Herzzentrum Leipzig, Leipzig, Germany Background. Conventional saphenous vein harvest is associated with numerous complications, which may be reduced by minimally invasive vein-harvesting techniques. The integrity of the venous endothelium must be guaranteed before using new saphenous vein harvesting techniques. This short-term study compared the clinical outcome of two minimally invasive techniques with the conventional technique, and compared morphology as documented by light and electron microscopy. Methods. Ninety-two patients were prospectively randomized into three groups. Two different minimally invasive techniques of greater saphenous vein harvesting were used in sixty-two patients. One used a videoassisted dissector (group A, n 31), and one used a lightcoupled retractor (group B, n 31). Thirty patients were treated by the conventional technique (group C). Results. Incision lengths were cm in group A and cm in group B, as compared with cm in the conventional group. Harvesting time was prolonged by a mean of 26% when using a minimally invasive technique. Conversion rate to the open technique was 3 of 31 (9.3%) in group A and 2 of 31 (6.2%) in group B. No wound complications were noted in group A, but one wound inflammation was seen in group B; only a mild hematoma was seen in both groups. Edge necrosis, wound separation and inflammation were noted in the conventional group. Light and electron microscopy revealed no significant denudation of the endothelial layer in groups A and B as compared with group C. Conclusions. These data show an excellent postoperative result when using the minimally invasive technique as compared with the conventional group. The safety of the technique is demonstrated by the preservation of endothelial integrity. (Ann Thorac Surg 2000;70:473 8) 2000 by The Society of Thoracic Surgeons The saphenous vein is routinely dissected in an open technique by a long incision through the skin and subcutaneous tissue. Complications of the traditional harvesting technique include hematoma, ecchymosis, seroma, edema, infection and skin necrosis, with an incidence up to 44% [1, 2] that may lead to prolonged hospitalization. Minimally invasive techniques that reduce postoperative morbidity may have potential financial implications due to early ambulation. Preservation of the endothelium layer is essential for conduit patency. Damage or denudation of endothelium may lead to increased deposition of platelets with the associated increased risk of thrombosis [3]. When applying new techniques, preservation of the endothelium layer must be guaranteed. We studied the morphology of human saphenous veins harvested by minimally invasive techniques by light and electron microscopy as compared with veins taken by the conventional technique. Accepted for publication Jan 24, Address reprint requests to Dr Fabricius, Klinik für Herzchirurgie, Herzzentrum Leipzig, Russenstrasse 19, D Leipzig, Germany. Patients and Methods Ninety-two patients were prospectively randomized into three groups. Two different minimally invasive techniques of saphenous vein harvesting were applied in 62 patients. One used a video-assisted dissector (group A), and one used a light-coupled retractor (group B). Thirty patients were treated by the conventional technique (group C). Randomization was done in an alternating manner. Patients who suffered from peripheral vascular disease or extensive varicosisitis were excluded. All procedures were performed by the same surgeon. Patients were comparable in terms of gender, age, obesity, and diabetes mellitus (Table 1). Analysis was performed with the intention-totreat methodology. Harvesting time of patients in groups A and B converted to the open technique are listed in Table 1. Any trauma during harvest, length of the incision and procedural time, with the intention to treat methodology, were recorded. Postoperative wound healing was recorded, and anemia ( 10 g/dl), ecchymosis, hematomas, inflammation, saphenous neuralgia and healing delay were noted on the third and sixth postoperative day. Inflammation was noted if clinical signs like rubor, calor, tumor, and dolor were present. Pain was not evaluated, and neither intraoperative nor postoperative narcotics were taken in account. Before enrollment and randomization, each participant 2000 by The Society of Thoracic Surgeons /00/$20.00 Published by Elsevier Science Inc PII S (00)

2 474 FABRICIUS ET AL Ann Thorac Surg MINIMALLY INVASIVE ENDOSCOPY VEIN HARVEST 2000;70:473 8 Table 1. Preoperative Characteristics and Harvest Sights Variables Group A Group B Group C p Value Patients mean age (years NS SD) sex [m/f] 20/11 17/14 20/10 NS diabetes NS obesity (BMI NS kg/m 2 ) Harvest site Thigh Calf Thigh and calf BMI body mass index; Group A video-assisted dissector; Group B light coupled retractor; Group C conventional technique; p 0.05; SD standard deviation. provided written, informed consent. Statistical analysis was done using the nonpaired Student s t-test for continuous variables and Fisher s exact test for categoric data. Statistical significance was defined at p-values less than Table 2. Intraoperative and Postoperative Characteristics of Patients Variable Group A Group B Group C p Value Number of grafts 37 ( ) 49 ( ) 40 ( ) NS Time required [min SD] Time for conversion [min SD] Incisions Lengths of all incisions [cm SD] Lengths of one incision [cm SD] Conversion to open technique Anemia NS Graft exclusion Bypass patching Wound healing correct inflammation separation NS cellulitis lymphangitis drainage edgenecrosis NS abscess lymphedema NS Ecchymosis hematoma none marked NS Group A video-assisted dissector; Group B light coupled retractor; Group C conventional technique; P 0.05; SD standard deviation. Surgical Technique Both minimally invasive techniques have been applied and previously described [4, 5]. Briefly, the endoscopic approach (group A) required video assistance using commercially available instruments, including a subcutaneous dissector, a retractor and a vessel dissector. A fiber-optic camera with a 30 angled 5.5-mm lens was used. A clip applier (Surgiclip, Autosuture, Norwalk, CT) was used for hemostasis. The patient was placed in a supine position throughout the procedure. After usual preparation of the leg, a 3-cm transverse skin incision 8 cm above the medial ankle, or 6 cm above the knee, was applied and the vein prepared under video control. The convex dissector was introduced through the incision and gently pushed forward through the perivascular tissue along the anterior plane of the vein. When pulling the dissector upward, a cavity was created instantaneously, allowing insertion of such instruments as a vessel dissector for separating the vein from the perivascular tissue or a clip applier. Impaired vision by bleeding was never a real problem; the dissector was removed, the blood wiped out of the channel and the endoscopic lens cleaned and reinserted. We intentionally did not use any cautery so as not to impair the postoperative outcome and to avoid subcutaneous necrosis, as well as accidental injury of the conduit or of thick sidebranches. Once the length needed for bypass was dissected, a 1-cm incision over the proximal vein was performed, and the conduit was ligated under direct vision and removed. We preferred this technique to tying the saphenous vein with a loop because we found the former technique to be safer. Sidebranches were ligated or clipped. No redon drainage was applied. The incisions were closed with 4-0 Prolene (Ethicon, Somerville, NJ), and the leg was immediately wrapped with an elastic bandage for 24 hours. The minimally invasive harvest system (group B) included a light-coupled retractor (Mini Harvest System, Autosuture, Norwalk, CT ), which came with two different dimensioned supports to elevate the retractor against the leg. After a 2.5-cm-long incision was made 8 cm above the medial ankle, a short segment of the vein was prepared and the blade of the retractor gently forwarded into the anterior perivascular tissue. Depending on the length of the calf or thigh, one or two additional incisions had to be made. Through the keyhole created, the vein was prepared under direct sight using conventional scissors and a clip applier (Surgiclip; Autosuture, Norwalk, CT). When preparing downward to the distal end of the calf s vein, the surgeon s head had to be moved down considerably to gain good sight into the channel. When working upward toward the knee, the leg was lifted by placing the heel on the operator s chest for better expo-

3 Ann Thorac Surg FABRICIUS ET AL 2000;70:473 8 MINIMALLY INVASIVE ENDOSCOPY VEIN HARVEST 475 Table 3. Histologic Assessment of Vein Rings Group A (n 28) Group B (n 29) Group C (n 30) converted veins (n 5) Preparation for Histology Two nondistended, 2-cm-long transverse segments were cut. One ring was stored in 10% buffered formaldehyde for histology. The other ring was stored in 4% buffered glutaraldehyde for electron microscopy and cut longitudinally into 1-mm 2 squares after 1 hour of prefixation. Further preparation and examination were done anonymously by a pathologist blinded to the mode of harvesting: paraffin-embedded tissue was stained with Hematoxylin/Eosin, semi-thin cuts before electron microscopy were stained with Giemsa (Dr K. Hollborn, Heipzig, Germany). Segments of all veins taken were assessed by scanning electron microscopy using morphological and descriptive criteria, such as endothelial intima coverage, cell dissociation and cell loss, as well as depositions, collagen fiber bundles, thromba and intima fractures. Additionally, Hematoxylin/Eosin and semi-thin cuts were graded into six categories (Table 3) according to the extent of endothelial denudation varying from grade 1 (less than 1%, grade 2 (up to 10%, grade 3 (10 30 %, grade 4 (50 90%, grade 5 (50 90% to grade 6 (greater than 90%. Veins of converted patients were assessed separately. Grade 1 ( 1% Grade 2 (up to 10% Grade 3 (10% 30% Grade 4 (50% 90% Grade 5 (50% 90% Grade 6 ( 90% 25 (89.3%) 26 (89.7%) 26 (86.6%) 5 (100%) 1 (6.9%) 3 (10.7%) 2 (6.8%) 4 (13%) Group A video-assisted dissector; Group B light coupled retractor; Group C conventional technique; n 92. sure, always taking care of aseptic conditions of the operation field. For dissection of the vein in the calf toward the sapheno-femoral junction, the leg was abducted. The vein was clipped at its proximal and distal end and taken out. Skin incisions were closed with 4-0 Prolene and the leg wrapped immediately with an elastic bandage for 24 hours. Patients of group C and patients converted from groups A and B were treated by the traditional open technique of vein harvesting with one long incision. The incisions were closed with a subcutaneous 3-0 Vicryl (Ethicon, Somerville, NJ) and the skin adapted with 4-0 Monocryl (Ethicion, Somerville, NJ). Results Patients characteristics are shown in Table 1. Vein harvesting was performed either in the thigh or the calf, or both. Statistics of harvesting time, incision lengths, and postoperative wound healing are summarized in Table 2. Complications of Group A included conversion to the traditional open preparation in three patients due to tissue adhesions tethering the vein to the skin in one patient, and in two patients due to side branches running toward the skin, which made it technically impossible to advance the dissector without notching the vein. Another vein was partially notched and excluded for bypass, and four veins had to be patched with 7-0 Prolene suture due to small side-branch avulsion. One patient showed local inflammation of the incision, ecchymosis developed in 25 patients and resolved within 3 days, and a hematoma developed in one patient due to removal of the elastic bandage too early. Anemia was noted in one patient. Group B had three major complications. The harvest technique had to be converted to the traditional open preparation in two patients: one patient had no suitable saphenous vein, and the other patient s vein showed strong tissue adhesions to the skin that could not be dissected freely in the created tunnel. Three veins had to be patched with 7-0 Prolene suture due to small sidebranch avulsion. Ecchymosis seen in 9 patients resolved within 2 days, and wound separation and inflammation were seen in one patient each. Anemia was noted in two patients. Harvesting time was prolonged by a mean of 26% in the minimally invasive groups, but wound healing was uncomplicated and no saphenous neuralgia occurred. Scarring was minimal, with the total incision length reduced to less than 25% in both groups. Harvesting time of patients converted to the conventional technique had longer times compared with the minimally invasive techniques (Table 2). Nine patients of group C treated with the conventional technique showed marked local inflammation. Lymphedema and slight wound separation developed in one patient, edge necrosis in five patients and ecchymosis in six patients. All patients of group C showed normal blood values (Fig 1). Histology All vein segments, regardless of the technique taken, revealed no significant difference. The overlying endothelial blanket in all specimens appeared well preserved and was neither shredded nor fissured. No portions of the underlining basement membranes were exposed or notable adherence of red blood cells or platelets suggesting denudated, thrombogenic surfaces, was seen. Grade 1 was encountered in 89.3% (25 of 28) of the specimens in group A, in 89.7% (26 of 29) of the speci-

4 476 FABRICIUS ET AL Ann Thorac Surg MINIMALLY INVASIVE ENDOSCOPY VEIN HARVEST 2000;70:473 8 Fig 1. Representative histologic samples of human saphenous vein harvesting in the conventional technique (A), or harvested by light coupled retractor (B) or by endoscopic technique (C). Endothelial integrity was preserved at all times. mens in group B and in 86.6% (26 of 30) in group C. Grade 2 was seen in only one vein sample of group B in 3.4% (1 of 29) of the samples. The other grading classes up to 5 could not be encountered in any of the samples, whereas grade 6 was detected in 10.7% (3 of 28) of the specimens in group A, in 6.9% (2 of 29) of the specimens in group B and in 13% (4 of 30) in group C. Converted veins (group A: 3/group B: 2/group) were assessed separately, and less than 1% denudation grade 1 was detected (Table 3). When extensive denudation (grade 6) was seen, no adherence of red blood cells or platelets was detected. In addition, discrete endothelial edema was detected in some of the samples. We concluded both findings were due to preparation artifacts that occurred postoperation. Intravascular cell debris attached to the endothelium consisted of different singular corpuscular blood cells. Another study of the specimens with electron microscopy again showed no differences between the harvesting techniques: no significant patches of endothelial layer were shredded on any section and, again, no basement membrane was exposed. Gap junctions were intact at all times. Endothelial cell retraction was minimal in all samples including converted veins and no groups of red cell or platelet adherence were seen. Different singular corpuscular blood cells and fibrin, accounting for normal intraluminal cell debris, were present. Comment Saphenous vein harvesting for coronary bypass operation is now a routine operation. Traditional harvesting techniques using a long incision over the vein may be challenged by less invasive procedures if these methods prove to be feasible in terms of technique, economics and time. However, benefit for the patient can be expected

5 Ann Thorac Surg FABRICIUS ET AL 2000;70:473 8 MINIMALLY INVASIVE ENDOSCOPY VEIN HARVEST 477 only if postoperative discomfort is reduced and conduit quality is guaranteed. Minimally invasive techniques to harvest the saphenous vein have improved and evolved by using common instruments, such as a Richardson retractor (Aesculap, Tuttlingen, Germany) [6] or a lighted retractor [7] besides using commercially available, minimally invasive endoscopic instruments [4], even with carbon dioxide insufflation [8] or newly designed lighted retractors [5]. Clinical experiences have demonstrated the technical feasibility of these new techniques, and although always more time consuming [9 11], have shown reduced postoperative morbidity, pain [4,5,10,11] and earlier ambulation [8]. However, the most important variable is the effect of harvesting technique on graft patency. Excess traction and increased manipulation of the vein, especially in minimally invasive harvesting techniques, may compromise conduit quality [12] and patency due to endothelial denudation. So far, histological examination of minimally invasive harvested vein segments by light microscopy have shown no significant damage to the vessel wall [13 15]. In our study, we focused on feasibility, on postoperative clinical results, and on the morphological properties of the minimally invasive, harvested saphenous veins. Both techniques are acquired rapidly during a learning curve of 5 to 10 patients. The saphenous vein was always harvested simultaneously with the mammary artery by different surgeons. However, procuring three grafts always took longer than the traditional way, thus prolonging operative time, which excludes both techniques for emergency surgical procedures. Preparing the saphenous vein in the thigh was technically easier than preparing it in the calf, since the skin is more flexible and the cavity created is greater. Nevertheless, the procedure should always start above the ankle so that no conduit material is wasted for a possible re-operation. The endoscopic technique requires just two incisions, whereas the retractor technique often requires three incisions on the calf or thigh. When using the endoscopic approach, the subcutaneous dissector is always easily pushed forward through the subcutaneous tissue. If sidebranches run toward the skin, then the dissector might get stuck or the vein notched, and conversion to the traditional open technique could be required. Through circumferential dissection when using the vessel dissector, only greater lateral branches are identified; tributaries hidden within the perivascular tissue are ripped off easily, thus reducing conduit quality. As in previously published studies, the minimally invasive technique yielded superior cosmetic results and reduced wound complications [16, 17], compared with the conventional technique [18], only one trial showed substantially lower wound complications in the conventional group [19]. Clinically, all minimally invasive treated patients had an improved postoperative wound healing due to short incision length and earlier ambulation due to absence of the incision at the medial knee region. The most common problem in the minimally invasive groups was ecchymosis or mild hematoma, [20, 21]. Impaired wound healing in the conventional group in our study was 46%; the incidence of impaired healing in a comparable group of patients has been reported to be between 27% [5] and 43.8% [1]. None of the patients required repeat hospitalization or reoperation for wound complications. Shear stress may be severe with blunt dissection of strong perivascular tissue as compared with sharp preparation using conventional scissors under direct vision in applying the conventional no-touch technique. Surprisingly, histology and electron microscopy revealed no morphologic differences when using one of the minimally invasive techniques compared with the traditional procedure. For the surgeon who prepared the vein in this study, the degree of mechanical manipulation seemed to be higher despite all efforts of treating the graft as gently as possible. This observation of course is rather subjective and cannot be graded, but we find it worthwhile to be noted. However, one has to take into account that only a small vein segment of the whole graft has been examined. The most interesting anatomical landmark to look at would be the vein wall where tributaries branch off, because mechanical manipulation is at maximum here, but ethical limitations do not allow a thorough examination. Unfortunately, both techniques require expensive or disposable instruments, or both, and the endoscopic approach requires additional costly video equipment. Although expensive, both techniques may offer a particular benefit if applied routinely especially to adipose and diabetic patients in reducing postoperative complications. As techniques and instrumentation for minimal harvesting are refined, reusable instrumentation will likely be developed and result in additional cost savings. In conclusion, we have demonstrated that minimally invasive saphenous vein harvesting techniques are technically feasible, and are associated with better cosmetic results and fewer wound complications. Furthermore, the procedure is safe, as we confirmed by the preservation of the saphenous vein endothelium. References 1. Wipke-Tevis DD, Stotts NA, Skov P, Carrierri-Kohlman V. Frequency, manifestations, and correlates of impaired healing of saphenous vein harvest incisions. 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