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a Department of Cardiothoracic Surgery, Aalborg Hospital, University of Aarhus, Hobrovej, postboks 365, DK-9000 Aalborg, Denmark
b Center for Cardiovascular Research, Biostatistical Unit, Aalborg Hospital, University of Aarhus, Hobrovej, postboks 365, DK-9000 Aalborg, Denmark
Received 10 December 2007; received in revised form 9 April 2008; accepted 23 April 2008.
* Corresponding author. Tel.: +45 99322975; fax: +45 99322425. (Email: jan.jesper.andreasen{at}stofanet.dk).
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Abstract |
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 Top Abstract 1. Introduction2. Materials and methods3. Results4. DiscussionReferences |
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Key Words: CABG • Endoscopic procedures • Outcomes • Wound infection • Pain
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1. Introduction |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionReferences |
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Conventional open vein harvesting (OVH) from the lower leg is routine in many centers when only a short vein segment is needed as it is easiest to harvest a short vein segment from the calf. An alternative would be EVH from the upper leg. Although it is possible to perform EVH from the whole leg, EVH of a short vein segment is most easy to perform from the thigh. In daily practice surgeons may have to choose between OVH of a short vein segment from the calf and EVH from the thigh. We therefore investigated in a randomized trial, firstly, whether leg wound morbidity was reduced after EVH from the thigh compared with open vein harvesting (OVH) from the calf, secondly, whether EVH would reduce pain, length of hospital stay, improve cosmetic results and reduce the need for home care and additional visits to the family physician or hospital after discharge. The benefits of EVH may not be evident if only short vein segments are harvested.
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2. Materials and methods |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionReferences |
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During the study period from April 2004 to June 2007, 1112 patients were admitted to the Department of Cardiothoracic Surgery, Aalborg Hospital, Denmark for isolated CABG. Aalborg Hospital is a public university affiliated hospital serving a population of approximately 600,000 people. A total of 595 patients were eligible for this single center, prospective, randomized study, comparing EVH with OVH of short vein segments for CABG. Patients were candidates for inclusion in the study if the surgeon by preoperative evaluation planned to use a short saphenous vein segment alone or in addition to arterial conduits, and if the surgeon with experience in EVH was available. A short vein segment was defined as a vein segment which could be harvested from the calf alone by the open technique without extending the incision beyond the knee. A total of 133 non-consecutive CABG patients were assessed for enrolment. One patient refused to participate, leaving 132 to be randomized into either EVH or OVH groups. The randomization schedule was provided in sealed, unlabeled and unordered envelopes. Blocking was used to ensure a close balance of the numbers in each group at any time during the trial. After a block of every 10 participants, five would be allocated to each arm of the trial. Patients were not admitted to the study if any of the following criteria were present: (1) urgent or emergent surgery, (2) varicose veins, (3) previous infrainguinal vascular surgery, (4) concomitant cardiac surgery, (5) re-do cardiac surgery, (6) previous apoplectic insult with neurologic sequelae in the legs, (7) a history of deep vein thrombosis in the legs, (8) pregnancy, (9) age below 18 years and (10) written informed consent could not be provided. During the early study period patients with a logistic EuroSCORE >6 (European system for cardiac operative risk evaluation [4]) were excluded, but later the EuroSCORE was not part of the exclusion criteria.
Preoperative variables analyzed were those outlined in Table 1 and intraoperative data collected are outlined in Table 2 . Time for vein harvest was defined as time from skin incision to skin closure. Postoperative outcome data collected were re-operation due to bleeding or infection related to the harvest site. We collected the following information regarding wound morbidity at day 5 and at around day 30: (1) cellulitis defined as presence of diffuse inflammatory redness of the skin, (2) purulent leg wound infection defined as infection in the skin and subcutaneous tissue with purulent secretion from the wound and/or surgical wound revision or rupture with positive culture from evacuated material and/or bacteria isolated from a subcutaneous or a subfascial collection in primarily closed wounds, (3) hematoma defined as a localized collection of blood with fluctuance, (4) suggillations or ecchymoses defined as hemorrhagic non-fluctuating macules in the skin >2 cm in diameter, (5) skin necrosis requiring additional need of wound cleansing and changing of wound dressings, (6) neuropathia of the skin defined as numbness and/or paresthesia of the skin, (7) wound dehiscence requiring additional need of wound cleansing and changing of wound dressings, (8) leg pain, assessed using a numeric scale from 0 to 10 with 0 representing no pain and 10 the most severe pain imagined, (9) hospital stay, defined as the time from the day of surgery until discharge to the home including time in a local hospital. It was also registered whether discharge to the home was postponed due to leg wound disturbances, (10) need of home care nursing due to wound morbidity (11) additional visits to the family physician or readmission to the hospital/outpatient clinic, (12) cosmetic result as judged by the patient on a scale graduated as follows: unacceptable = 1, not satisfied = 2, satisfied = 3, very satisfied = 4 and extremely satisfied = 5. Further we collected information regarding (1) perioperative myocardial infarction defined as creatine kinase MB values of greater than 50 µg/l in combination with a new Q-wave in the ECG, (2) early graft occlusion identified by coronary angiograms or during re-operation, (3) deep sternal wound infection defined as sternal dehiscence and/or surgical wound revision with finding of pus and/or culture positive infection involving sternum and/or mediastinum and (4) mortality (30 days + hospital mortality).
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All patients in the EVH group were analyzed by the intention-to-treat principle. Patients converted to the open technique were kept in the EVH group, as any leg wound complication would be related to initial attempt and time used for EVH from the thigh and what subsequently followed.
2.2 Surgical techniques
Routine thoracic surgical and anesthetic procedures were employed. Transesophageal echo was not available in all patients. Whether surgery was performed as on-pump or off-pump cases was left to the discretion of the surgeons. All legs were prepared with circumferential chlorhexidine (Klorhexidinsprit farvet, Amternes lægemiddelregistreringskontor I/S, Copenhagen, Denmark) prior to vein harvesting. Prophylactic antimicrobial chemotherapy for 48 h consisted of cefuroxime 1.5 g (GlaxoSmithKline Pharma A/S, Brøndby, Denmark) and gentamicin 240 mg (Sandoz A/S, Odense, Denmark) intravenously prior to skin incision.
A single surgeon (JJA) harvested all veins in the EVH group after having completed 30 EVH cases in order to overcome the learning curve. EVH was performed prior to systemic heparinization. All veins in the OVH group were to be harvested by experienced cardiothoracic surgeons. The wounds were closed as soon the vein was harvested and covered with a dry sterile dressing. All legs were wrapped with an elastic bandage until the next morning.
2.2.1 Endoscopic vein harvesting
The Guidant VasoView® 5 Endoscopic Harvesting System (Guidant Corporation, CA, USA) was used for the initial 31 patients and hereafter the Guidant VasoView® 6 System. The harvesting systems were purchased from the local Guidant cardiac surgery territory manager (Hemax Medical Aps, Denmark).
A 2–3 cm skin incision was made medially above or just below the knee area. Under direct visualization the saphenous vein was dissected proximally, creating a small space for introduction of a 7 mm extended length endoscope (Guidant Corporation, CA, USA), with an attached transparent conical tip at the distal lens of the scope. When the endoscope was inserted into the incision, the vein was visualized on a video monitor. Blunt dissection of surrounding tissue from the vein was done towards the groin while CO2 was insufflated into the sealed off subcutaneous tunnel at a maximum CO2 pressure of 15 mmHg. Side branches of the vein were divided using integrated bipolar cautering. A stab incision was created over the tunnel proximal on the thigh. Under endoscopic vision a hemostat clamp was inserted into the tunnel through the puncture site and the vein was pulled out through the puncture site, divided and removed through the distal incision. The vein was immediately flushed and gently manually pressure distended with a solution containing 20 ml autologous blood, 100 ml heparin, 25 IE/ml (Amternes Lægemiddelregistreringskontor I/S, Copenhagen), and 2 ml papavarine, 30 mg/ml (Amternes Lægemiddelregistreringskontor I/S, Copenhagen). The vein was kept in the same solution at room temperature until used. Side branches and avulsions were closed using ligating clips, ligatures and/or polypropylene sutures as appropriate. The wound at the knee was closed in two layers: a subcutaneous running absorbable suture of 3-0 Ethicon Vicryl (Johnson & Johnson), and a running suture of nylon 4-0 (Monosof, Syneture) in the skin. The proximal wound was just closed with nylon in the skin.
2.2.2 Open vein harvesting
The saphenous vein was exposed through a longitudinal continuous incision over the vein starting just proximally to the medial malleolus. The incision was extended proximally but never beyond the knee. Side branches were divided between ligating clips and/or ligatures of vicryl. All veins were isolated without surrounding tissue. After the vein was removed it was treated in the same way as described for EVH. The wound was closed in two layers: a subcutaneous running absorbable suture of 3-0 Ethicon Vicryl (Johnson & Johnson) and the skin was closed with a running intracutaneous absorbable suture of Monocryl 3-0 or 4-0 (Ethicon, Johnson & Johnson). Suction drainage was not used as a routine.
2.2.3 Postoperative care
Postoperative care was standardized. For pain control morphine was usually the drug of choice in combination with paracetamol (Paracetamol, Amternes Lægemiddelregistreringskontor I/S, Copenhagen, Denmark). Statins and acetyl salicylic acid was started as soon as possible. Patients who were on clopidogrel due to preoperative myocardial infarction or episodes of unstable angina also resumed oral intake of clopidogrel postoperatively. Patients were transferred to local hospitals on day 5 if further cardiothoracic surgical expertise was not mandatory.
2.2.4 Statistical analysis
We believed that the incidence of wound morbidity would be 30% in the OVH group and 10% in the EVH group. Based on 0.8 power to detect a significant difference (p
0.05), 60 patients were required for each study group. To compensate for non-evaluable patients we planned to enrol 66 patients per group. The two groups were compared using t-tests for continuous variables and chi-squared tests for categorical variables. Wilcoxon rank-sum tests were used to compare the distributions of the following quantities between the groups: length of hospital stay and number of visits by physician or home care nurse. The relative risk (RR) with 95% confidence intervals (CI) for developing leg wound morbidity was calculated using Poisson regression with robust variances [5]. Analyses were both crude and adjusted for logistic EuroSCORE, diabetes, smoking, hypercholesterolemia, albumin, preoperative intake of acetylsalicylic acid and clopidogrel.
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3. Results |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionReferences |
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Preoperative baseline demographic and patient characteristics of the two groups were comparable (Table 1). Perioperative details are summarized in Table 2. In two EVH patients the vein harvest was performed from the calf following initial attempts on the thigh, and in two patients from the OVH group the vein was harvested from the thigh following initial attempts on the calf. Harvesting time was prolonged for EVH (mean ± SD: 53 ± 20 min) compared with OVH (mean ± SD: 34 ± 14 min). Time for EVH did not change significantly during the study period. Postoperative details are summarized in Table 3 . The median time from the day of surgery to 30-day control was 35 days (range: 21–49 days) without any difference between the groups. Purulent leg wound infection was only seen in the OVH group (11%). Only cellulitis, purulent wound infection, wound dehiscence and skin necrosis resulted in the need for additional visits for wound care after discharge. Nine patients in the OVH group needed one or more post-discharge visits. One of these patients was re-admitted to the hospital for surgical revision of the wound. Until wound healing was complete the overall number of visits by home care nurses or to the family physician and/or outpatient clinic was 79 in the OVH group and two in the EVH group. The unadjusted and adjusted RR for developing leg wound complications leading to additional post-discharge visits for wound care within the observation period was 0.64 (95% CI: 0.41–1.00) and 0.58 (95% CI: 0.37–0.92) in the EVH group (OVH as the reference).
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The overall pain scores were similar on day 5, but around day 30 the pain score was significantly higher in the OVH group. None of the patients had their discharge postponed due to wound morbidity. No abrupt hemodynamic changes, which could be related to CO2 embolism were observed during surgery. There were three non-cardiac related hospital deaths. No deaths were related to complications following vein harvesting. There were no episodes of recurrent angina during the time of observation, and none of the patients experienced myocardial infarction or need for re-angiography.
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4. Discussion |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionReferences |
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Among patients in the EVH group, the harvest time was significantly longer, but these patients suffered from fewer cases of infectious and non-infective wound complications, and there was a substantial reduction in the need for additional post-discharge visits by home care nurse or visits to the outpatient clinic or to the family physician.
Published leg wound morbidity rates following OVH vary substantially and impaired wound healing following OVH has been found in up to 46% of the patients [11]. Variations in wound morbidity rates may be explained by differences in wound complications reported, different definitions, differences in duration, different methods of follow-up and differences in study design. In addition, registration of wound infections may be incomplete even in prospective studies focusing on postoperative wound infection in CABG [12]. An incidence of 61% regarding numbness or tingling related to the leg wound following OVH has been reported [13]. The incidence of neuropathia in the present study was lower without any difference between the study groups. Complications such as numbness and hemorrhagic macules in the skin may be of minor concern compared to purulent infection, skin necrosis and wound dehiscence, which may require surgical re-intervention and/or prolonged need for wound care.
Most purulent leg wound infections are diagnosed within 30 days of surgery, but additional infections may be diagnosed if the follow-up period is extended to 60 days [14]. The infection rates in the present study may therefore be underestimated. The incidence of purulent leg wound infection in the OVH group was 11%. This is consistent with findings from prospective studies during the last decade where infection rates up to 21% following OVH have been reported [15]. It has been shown that the risk of leg wound infection is operator dependent. The incidence of postoperative infection is significantly lower in patients when vein harvest is performed by an experienced operator compared with less experienced residents [16]. In the present study all veins but one, were harvested by experienced surgeons, which means that the results may not be generalized to circumstances where less experienced surgeons are performing OVH. However, EVH may prove to be even more beneficial in these settings.
Conversion rates to the open technique among patients undergoing minimal invasive vein harvest with different techniques vary between 0 and 31% [1]. A conversion rate of 14% (9/66) is within this range, but higher than the conversion rates reported in a meta-analysis [3] on EVH (4.3%), and higher than reported in prospective studies (0–7.1%) using the VasoView System [8,10,17]. Conversion rates may decrease as operators become more skilled, and low conversion rates may be obtained by careful selection of patients.
The length of hospital stay was similar in both study groups and this is in accordance with previous findings in other studies using the VasoView System [7,9] although a meta-analysis of randomized and controlled trials [3] found a significant reduction in the length of stay following EVH with different techniques compared with OVH.
A main reason for the reduction in wound morbidity following EVH may be the short skin incision. In previous studies it has been shown that the incidence of leg wound morbidity increases with the length of the incision [18,19].
The harvest site may also influence complication rates. In a prospective observational study it has been shown that the ASEPSIS score was reduced when vein harvest was restricted to below the level of the knee [20]. In the OVH group all veins but two were harvested below the knee, but this did not result in lower wound morbidity compared to EVH from the thigh.
The wound closure technique may represent an important factor in prevention of postoperative leg wound infections [21]. It is a limitation of the study that the wound closure technique differed between the study groups. The transcutaneous technique was chosen for the EVH group because we found it easy to close the small incisions with the transcutaneous suture. Trans- and intracutaneous suture methods have been compared in CABG, but the results were not clear due to small sample sizes [15]. Therefore we have no reason to believe that the difference in wound closure techniques is a major confounder. It is also a limitation that use of analgesics was not registered, as less pain may be attributed to a higher intake of analgesics.
Preoperatively we registered a history of symptomatic arteriosclerotic occlusive disease, but we did not include objective signs of critical ischemia of the lower limbs, which may have been more precise independent risk factors for postoperative impaired wound healing. We believe that assignment to the study groups randomly equalized these risk factors if they were present among patients.
We did not measure the length of the vein grafts harvested, but we estimate graft lengths to be comparable in the two groups as the number of vein anastomoses was identical in the two groups.
The number of harvested veins requiring repair and the number of repairs to each vein may be of interest in relation to patency rates of veins conduits. We did not address these outcomes in the present study, but a meta-analysis [2] comparing EVH and OVH has shown that EVH and OVH conduits are comparable with regards the proportion of veins requiring repair, but EVH conduits required a significantly larger number of repair. Whether this will translate into reduced long-term patency rates for EVH conduits remains to be investigated together with the impact of potential residual clot strands within the EVH conduits harvested without preheparinization [22].
No abrupt hemodynamic changes, which could be related to CO2 were observed during surgery in the present study, but massive CO2 embolization leading to significant hemodynamic alterations occurred in 2 out of 405 patients (0.5%) in a previous study in which embolization of different severity was detected in up to 17.1% [23]. The incidence of CO2 embolisms during EVH may be reduced with lower CO2 insufflation pressure, which, in combination with increased surgical experience and continuous transesophageal echocardiography monitoring of the inferior vena cave may reduce the risk of massive CO2 embolism [24].
A major strength of this study is the prospective, randomized nature of the study with meticulous focus on leg wound morbidity. Retrospective studies have an inherent risk of underestimating through infection rates.
Patients were included in this study over a period of 3 years, which is a relatively long period of time for this study. This is explained by the fact that only one surgeon was involved in EVH and patients could only be included in the study if the surgeon with EVH experience was available. However, we do not suspect the relatively long study period to have any influence on the results of the study as clinical routines were not changed during the study, and blocking was used during randomization to ensure a close balance of EVH and OVH numbers in each group at any time during the trial.
Cosmetics remain secondary to patency rates of the conduits. Angiographic studies on early patency rates up to 6 months have shown that conduits harvested using the VasoView System have similar patency rates [9,10]. None of the patients in the present study were diagnosed with myocardial infarction, which might be a clinical sign of graft occlusion.
In conclusion EVH of a short saphenous vein segment from the thigh during elective CABG results in less wound morbidity and better cosmetic results with a substantial reduction in the need for post-discharge wound care compared with OVH of a short vein segment from the calf. These results support the recommendation for EVH as standard care for patients who require saphenous vein grafts for coronary revascularization issued by the International Society of Minimally Invasive Cardiothoracic Surgery [25]. EVH has now been introduced as the preferred vein harvest technique in our center.
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Footnotes |
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The study was supported by grants from ‘Peder Kristian Tøftings og Dagmar Tøftings Fond’ and from ‘Vestdansk Sundhedsvidenskabeligt Forskningsforums konsulenttjeneste’. |
References |
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TopAbstract1. Introduction2. Materials and methods3. Results4. DiscussionReferences |
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