Diagnostic Dilemma: Management of Saphenous Vein Harvest Wound Complications Following Coronary Artery Bypass Grafting

CME/CPME Credits Available for Reading this Article Department Editor: Tania Phillips, MD, FRCPC Overall Learning Objective: The physician or podiatrist participant will develop a rational approach to the evaluation and treatment of a variety of uncommon wounds and will have an increased awareness of the differential diagnosis of cutaneous wounds and the systemic diseases associated with these wounds. Submissions: To submit a case for consideration in Diagnostic Dilemmas, e-mail or write to: Executive Editor, WOUNDS, 83 General Warren Blvd., Suite 100, Malvern, PA 19355, eklumpp@hmpcommunications.com Completion Time: The estimated time to completion for this activity is 1 hour. Target Audience: This CME/CPME activity is intended for dermatologists, surgeons, podiatrists, internists, and other physicians who treat wounds. At the conclusion of this activity, the participant should be able to: 1. Recognize that saphenous vein harvest wound complications are infrequent but serious problems following coronary artery bypass grafting 2. Recognize patients who are at risk for developing saphenous vein harvest wound complications 3. Describe and discuss current therapies available for treatment of saphenous vein harvest wounds that do not heal appropriately. Disclosure: All faculty participating in Continuing Medical Education programs sponsored by HMP Communications, LLC, are expected to disclose to the program audience any real or apparent conflict(s) of interest related to the content of their presentation. Dr. Treadwell discloses that he is an investigator and is on the speakers bureau for OrTec International and Novartis Pharmaceuticals Inc. Accreditation: HMP Communications, LLC, is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians. HMP Communications, LLC, is approved by the Council on Podiatric Medical Education as a sponsor of continuing education in podiatric medicine. Designation: HMP Communications, LLC designates this continuing medical education activity for a maximum of 1 credit hour in category 1 credit toward the AMA Physician’s Recognition Award. Each physician should claim only those hours of credit that he/she actually spent in the educational activity. HMP Communications designates this continuing medical activity for .1 CEUs available to participating podiatrists. Method of Participation: Read the article, take, submit, and pass post-test by March 10, 2004. This activity has been planned and produced in accordance with the ACCME Essential Areas and Policies. Release date: 3/10/03; Expiration date: 3/10/04 Management of Saphenous Vein Harvest Wound Complications Following Coronary Artery Bypass Grafting Presentation A 67-year-old African-American woman with insulin-dependent diabetes mellitus presented at the wound center with a left leg wound that extended from 9cm below the knee to just above the medial malleolus. History revealed the patient had undergone a coronary artery bypass grafting (CABG) operation one month prior to being seen at the wound center. Although the patient’s sternal wound had healed uneventfully, the saphenous vein harvest incision in the left leg had not healed. The patient had not required the use of an intra-aortic balloon pump during or after her operation. She had no history of intra-operative or postoperative cardiac or vascular instability, infection, coagulation problems, or coumadin therapy. She had no history of diabetic peripheral neuropathy or diabetic foot problems. There was no history of pre-operative peripheral vascular evaluation. Physical Examination At the time of her initial evaluation in the wound center, the patient’s wound was necrotic throughout its entire length; the stitches were still in place. No arterial pulses were palpable at the ankle, but there was biphasic flow in the dorsalis pedis and posterior tibial arteries by Doppler. The ankle/brachial index was 0.65. No cellulitis or other problems were noted. Diagnosis The patient was diagnosed with a nonhealing saphenous vain harvest incision following a CABG operation. Discussion CABG is one of the most frequently performed operations in the United States. The operation has an excellent success rate and has helped countless patients live longer, more fruitful lives. The conduit most often used for the bypass is the greater saphenous vein. Even though recent techniques have utilized other conduits for restoration of blood flow to the heart, the greater saphenous vein remains the mainstay of the operative procedure. One of the little discussed morbidities of the CABG operation is failure of the saphenous vein harvest wound to heal appropriately. More patients complain about their leg wounds than complain about their sternal wounds. The complications associated with saphenous vein harvest wounds may be as inconsequential as prolonged discomfort and slight dermatitis or as major as complete wound breakdown (Table 1). Saphenous vein harvest wound complications occur in 1 to 24 percent of cases, but the percentage of complications can be as high as 43 percent.[1–3] Fortunately, less than 50 percent of these wounds require operative intervention, but the ones that do can be major. Reported operative interventions have included debridement, fasciotomy, thromboembolectomy with or without bypass, delayed wound closure with skin graft or rotational flap, free tissue transfer, and even amputation.[1] Any complication requiring additional operative procedures subjects the patient to additional risk and delays the patient’s recovery and return to normal activity. Identification of the patient at high risk for developing a saphenous vein wound complication and appropriate preoperative evaluation could help reduce the risk of this problem. Risk factors for saphenous vein harvest complications. Prevention is obviously the best form of treatment. Patients at risk of developing a major saphenous vein harvest wound complication should be identified preoperatively. The significant risk factors of saphenous vein harvest wound complications are listed in Table 2. It is interesting to note that the patient’s age, length of the operative incision, duration of the operative procedure, and duration of aortic cross-clamping were not associated with a higher incidence of saphenous vein harvest wound complications. The association of the patient’s body mass and the presence of preoperative anemia have been variably associated with an increased incidence of vein harvest wound complications.[4,5] Saphenous vein harvest wounds are generally associated with the greater saphenous vein. As more secondary coronary artery bypass procedures and lower-extremity revascularization procedures utilizing the greater saphenous vein are done, other leg veins are harvested for use. Wound complications should be anticipated after removal of such veins as the lesser saphenous vein. Women. Since it is known that women are at a higher risk for developing postoperative saphenous vein harvest wound complications,[1] preoperative evaluation and protective measures should be done for all women undergoing CABG procedures. Why women are more susceptible to saphenous vein harvest wound complications is not apparent. It has been suggested that since many of these female patients undergoing CABG are postmenopausal, an estrogen deficiency may prevent uncomplicated healing.[1] Diabetes mellitus. It is well known that diabetes mellitus is a major risk factor for poor wound healing. Maximal control of the diabetes is mandatory prior to any operative procedure, especially one with metabolic implications, such as CABG operation. Diabetic control preoperatively and postoperatively is extremely important to minimize the effects of diabetes on the healing process. The diabetic patient should be routinely screened for the presence of significant lower extremity peripheral vascular disease prior to removal of the saphenous vein. Smoking. Smoking as a risk factor for development of a saphenous vein harvest wound complication is probably due to its relationship to peripheral vascular disease. Smoking can decrease local skin blood flow making an operative site potentially more ischemic. There has been recent information to suggest that smokers have decreased keratinocyte migration due to blockage of cell receptor sites by nicotine.[6] This cellular dysfunction could lead to healing problems. Obesity. Obese patients typically have more problems healing wounds or incisions than other patients. This is also true for the saphenous vein harvest wound in the leg.[4,5] The obese patient is more likely to develop a hematoma, lymphocele, wound infection, or wound healing problem than is the patient who is not obese. These potential problems can be minimized by meticulous care of the operative incision. It is important to achieve hemostasis and control lymphatic drainage. If there is any question about hemostasis, especially since the patient will be anticoagulated for the remainder of the procedure, judicious use of drains is appropriate. Adequate approximation of the subcutaneous tissues, in multiple layers if necessary, is a must to eliminate “dead space” in the wound. Excessive tension on the skin with sutures or staples must be avoided to minimize the possibility of skin necrosis. Low preoperative hematocrit levels. Utley and colleagues have noted an increase in the incidence of saphenous vein harvest wound complications in patients who have preoperative hematocrit levels of less than 35 percent.[5] This does not seem to be a consistent finding in other studies, but patients with preoperative anemia should have the anemia corrected and be watched closely for the development of wound problems. The postoperative dilutional anemia routinely seen in patients immediately following cardiac operations does not seem to be related to an increase in saphenous vein harvest wound complications. Peripheral vascular disease. The presence of pre-existing peripheral vascular disease greatly increases the risk of developing a saphenous vein harvest wound complication.[1,9] Patients with coronary artery disease have very high chances of having coexisting peripheral vascular disease. This is especially true for diabetic patients. Preoperative evaluation of the lower extremities to determine the extent of peripheral arterial ischemia is extremely important to minimize saphenous vein harvest wound problems. This can be critical if the vein below the knee will be used. Evaluation of the circulation is done by checking for pulses in the extremity. Because of the subjective nature of palpation of peripheral arterial pulses, it is necessary to do a Doppler evaluation of the ankle pulses and to measure the ankle blood pressure. Scher and associates have suggested that a leg with an ankle blood pressure of 50mmHg or less should not be used as a site for removal of the saphenous vein.[7] Most will evaluate this risk by calculating an ankle/brachial index (ABI). If the ABI is less than 0.70, further evaluation of the limb is needed. If the ABI is greater than 0.70 in one leg and not the other, the “good” leg can be used for the saphenous vein harvest. An ABI of 0.50 or less in a leg selected as the site for the saphenous vein harvest is not recommended.[1] If there is no other choice than to use a moderately ischemic extremity as the donor leg for the saphenous vein, the patient should have angiography of the lower extremities and revascularization of at least one leg prior to the cardiac procedure. Use of intra-aortic balloon pump. The incidence of ischemic limb problems with use of the intra-aortic balloon pump to support the heart has been reported to be from 20 to 30 percent.[8] The most frequent problem is ischemia of the extremity either due to arterial obstruction or thrombosis from use of the intra-arterial catheter. Occasionally, distal embolization or thrombosis will result in ischemic problems. This additional ischemic insult on an already compromised limb will certainly affect the wound healing ability of the leg. For this reason, it is wise to harvest the saphenous vein from the limb opposite the intra-aortic balloon insertion site. If ischemic problems should occur with use of the intra-aortic balloon pump, immediate attention to the problem with balloon pump removal, thrombectomy, or bypass is needed to assure limb viability and adequate wound healing. Operative technique. Many times, the removal of the saphenous vein is considered to be a secondary procedure and is assigned to the most junior member of the operating team. Operative technique in removing the vein plays a role in how the wound will heal (Table 3). It is imperative the operating surgeon correctly identify the path of the saphenous vein through its course in the leg. This will allow the vein to be removed with minimal dissection of the tissues and prevent large flaps from being developed as the surgeon searches for the vein. Damage to the greater saphenous nerve can result in postoperative discomfort for the patient. Identifying the nerve as it passes adjacent to the greater saphenous vein will minimize the chance of its being damaged during the dissection. Meticulous hemostasis is a must. All bleeding does eventually stop, but in the patient who will be anticoagulated for an operative procedure after the leg wounds are closed, large hematomas can develop from even the smallest bleeding vessel. The surgeon must take great care to avoid obvious lymphatic channels and control any visible lymphatic drainage in an effort to prevent the formation of lymphoceles. During the closure of the wound, the subcutaneous tissues must be carefully approximated to eliminate any “dead space” under the skin. This will minimize the chance of fluid collection in the subcutaneous tissues whether from lymph fluids, blood, or pus. The skin should be closed without tension to avoid ischemia of the skin edges. Failure to pay attention to this detail can result in necrosis of the skin along the course of the wound. The recently developed technique of endoscopic removal of the saphenous vein may be very beneficial for these patients. The vein is removed with an endoscope during a procedure that requires only two or three small incisions. This technique may reduce saphenous vein harvest wound problems,[9–12] but when a complication does occur, it may be more difficult to identify and treat.[13] Treatment If all preventative measures fail and a patient develops a saphenous vein harvest wound complication, immediate attention is a must. If the patient develops a hematoma, lymphocele, or abscess, prompt drainage is the treatment of choice. Good wound care techniques should be employed. Unfortunately, as illustrated by the case in this article, most of these patients are referred to wound care facilities late in the course of the problem when simple therapies are of little use. Many patients require operative intervention for the saphenous vein wound complication (Table 4). The type of operative intervention will vary depending on the extent and etiology of the problem. Ischemic problems must be managed by restoration of blood flow. After the circulation has been restored, the management of the wound can be addressed. If the circulation cannot be restored or the limb is deemed to be unsalvageable, amputation may be required. All patients will require some form of debridement of the unhealed wound. If the area of necrotic tissue is small, nonoperative techniques may be adequate. If the entire lower leg wound is involved, which is typically the case, operative debridement is indicated. After debridement is performed, standard moist wound care should be instituted. Most of these wounds are large enough that healing by secondary intention will require a protracted period of time delaying the patient’s return to normal activity. Historically, the treatment of choice has been delayed wound closure with a split-thickness skin graft, rotational flap, or free tissue transfer. All of these have their advantages, but each of these is not without potential problems. All have one thing in common—each requires another operative procedure, some rather formidable, which may be disadvantageous to many patients. There are treatments available for these higher-risk patients that do not require major operation procedures, as detailed below. Negative pressure wound therapy. Negative pressure wound therapy or vacuum-assisted closure (VAC) (V.A.C.®, Kinetic Concepts Inc., San Antonio, Texas) is suitable for some of these wounds. This therapy involves a sealed wound dressing system that applies negative pressure to the wound expediting closure.[14] Once the wound is debrided, the VAC device can be applied. With currently available equipment, the patient may remain ambulatory during therapy. Wound healing rates with this technique have been quite good, making this treatment useful for saphenous vein harvest wounds and other chronic wounds.[15] Living skin equivalent. Living skin equivalent (LSE) (Apligraf®, Novartis Pharmaceuticals Inc., East Hanover, New Jersey) provides another option for treatment of these wounds and has been used for numerous chronic and surgical wounds with excellent results.[16] The treatment of saphenous vein harvest wounds with LSE has been especially rewarding since the procedure can be done in the outpatient or office setting without the need for anesthesia. This therapy allows the patient to remain ambulatory during the healing process. LSE increases the healing rate of these wounds and promotes healing of some wounds that might require more extensive therapy were LSE not available. The author’s experience has shown that many patients with saphenous vein harvest wounds and marginal circulation can have successful wound healing without revascularization when treated with tissue-engineered skin. In the author’s experience, patients with ABIs as low as 0.45 have been successfully healed without revascularization. It is the author’s opinion the cosmetic result has been uniformly better when LSE has been used instead of a split-thickness skin graft. Despite the lack of melanocytes in the LSE, the patient’s normal skin color returns to the healed site resulting in a more normal appearing scar. LSE is very useful in treating wounds when other therapies have failed. The author treated 24 saphenous vein harvest wound complication patients with LSE and all patients uniformly healed without additional problems. Bilayered cellular matrix. The author treated two patients who had unhealed saphenous vein harvest wounds with a bilayered cellular matrix (BCM) product, OrCel® (OrTec International, Inc., New York, New York). BCM consists of human keratinocytes and fibroblasts in a bovine collagen matrix.[17] The author’s experience treating patients who had unhealed saphenous vein harvest wounds with fresh BCM resulted in uncomplicated healing and good patient satisfaction. Treatment of saphenous vein harvest wound patients with BCM has not been reported previously. Currently, this product is not available. Patient Management For the patient described in this case, the wound was surgically debrided to remove the majority of the necrotic tissue. The patient cleaned the wound herself twice daily with soap and water and applied an enzymatic debriding agent (Collagenase Santyl®, Smith & Nephew, Inc., Largo, Florida) followed by a moist dressing for further debridement, which the patient also applied herself. After three weeks, the patient’s wound was clean and granulating. The author felt this patient’s wound closure could best be optimized by application of LSE. The LSE was cut and placed on the wound to gain maximum coverage. The LSE was secured with Steri-strips and covered with gauze, a moist bolster, a dry dressing, and a mild compression bandage. The patient’s dressing was changed on the fourth day postapplication and weekly thereafter. Significant healing was obvious at 11 days following placement of the LSE. The wound was healed by six weeks postapplication. It is of note that the melanocytes were beginning to migrate into the healed wound scar six weeks postapplication of LSE and had significantly covered the wound scar by five months postapplication (Figures 1A–E). The patient has had no further problems with the leg or the wound. Conclusion Saphenous vein harvest wound complications following CABG are uncommon, but if one should occur, it can be very difficult to manage. Preoperative screening of patients with risk factors for developing a postoperative complication should help minimize the occurrence. Once a saphenous vein harvest wound complication occurs, prompt recognition and treatment should shorten the course of the wound healing. With late recognition and therapy, major operative procedures may be required to treat these wounds. Use of newer treatment modalities may be useful in the nonoperative treatment of these patients. How to obtain educational credits by reading this article Learning Assessment: Successful completion entails scoring at least 70 percent on the questions, printing off and completing the entire evaluation form below, and sending it to the correct address listed below. Certificates will be mailed to those who successfully complete the learning assessment by March 10, 2004. Fax or mail the completed form to: (610) 560-0501 Trish Levy, CME Director HMP Communications, LLC 83 General Warren Blvd. Suite 100 Malvern, PA 19355 Questions 1. Following coronary artery bypass grafting operations most patients complain about their: A. Sternal wound B. Saphenous vein harvest wound C. Exercise program D. None of the above 2. Which of the following would be considered a major risk factor for developing a saphenous vein harvest wound complication? A. Diabetes mellitus B. Female C. Smoking D. All of the above 3. Saphenous vein harvest wound complications can occur after removal of which of the following veins? A. Greater saphenous vein B. Lesser saphenous vein C. Both D. Neither 4. It is possible that women are at higher risk than men for developing a saphenous vein harvest wound complication because of: A. Obesity B. Shorter legs C. Estrogen deficiency D. None of the above 5. The obese patient is most likely to develop which of the following saphenous vein harvest wound complications? A. Hematoma B. Lymphocele C. Abscess D. All of the above 6. Preoperative screening for the patient with diabetes mellitus should include: A. Body mass evaluation B. Peripheral vascular disease evaluation C. Calorie count D. None of the above 7. Evaluation of the lower extremities for ischemia should include: A. Palpation of pulses B. Doppler evaluation of pulses C. Measurement of ankle blood pressure and calculation of the ABI D. All of the above 8. Operative techniques in removing the saphenous vein should include: A. Meticulous hemostasis B. Elimination of “dead space” in the subcutaneous tissue C. Skin closure with minimal tension D. All of the above 9. Operative management of the saphenous vein harvest wound complication has included: A. Debridement B. Split-thickness skin graft C. Free tissue transfer D. All of the above 10. Advantages for treating saphenous vein harvest wounds with the V.A.C. device or tissue engineered skin include: A. Treatment does not require a major operative procedure B. Patients can remain ambulatory during therapy C. Wound healing rates are increased over healing by secondary intention alone D. All of the above Saphenous Vein Harvest Wound Complications Answer Form and Evaluation Please print this off and fill it out completely and clearly: Name Degree Position/Title Organization/Institute Department Mailing Address for Certificate (H or W): City State Zip Code Email Address Social Security Number Phone (area code) Fax (area code) Answers (Refer to questions above) Circle one letter for each answer: 1. A B C D 2. A B C D 3. A B C D 4. A B C D 5. A B C D 6. A B C D 7. A B C D 8. A B C D 9. A B C D 10. A B C D Evaluation (circle one) -- Excellent (4) Good (3) Satisfactory (2) Poor (1) Accuracy and timeliness of content: 4 3 2 1 Relevance to your daily practice: 4 3 2 1 Impact on your professional effectiveness: 4 3 2 1 Relevance of the content to the learning objectives: 4 3 2 1 Effectiveness of the teaching/learning methods: 4 3 2 1 This activity avoided commercial bias or influence YES NO Now that you have read this article, can you: 1. Recognize that saphenous vein harvest wound complications are infrequent but serious problems following coronary artery bypass grafting? YES NO 2. Recognize patients who are at risk for developing saphenous vein harvest wound complications? YES NO 3. Describe and discuss current therapies available for treatment of saphenous vein harvest wounds that do not heal appropriately? YES NO What questions do you still have?___________________________________ How will you use what you have learned from this activity?________________ All tests must be received by 3/10/04.