Abstract
Objectives
Endoscopic vein harvest (EVH) has been demonstrated to improve early morbidity when compared with conventional open harvest technique (OVH) for infrainguinal bypass surgery. However recent literature suggests conflicting results regarding mid and long-term patency with EVH. The purpose of this study is to compare graft patency between harvest techniques specifically in patients with critical limb ischemia (CLI).
Methods
This retrospective study compared two groups of patients (EVH=39 and OVH=49) undergoing lower extremity revascularization from January 2009 to December 2011. Outcome measures included patency rates, postoperative complications and wound infection. Graft patency was assessed using Kaplan-Meier curves.
Results
Both groups were matched for demographics and indications for bypass (CLI). Median follow up was 22 months. There was a significant reduction in the incidence of wound infection at the vein harvest site in the EVH group (OVH=20%, EVH=0%, P < .001), nevertheless the difference was not significant when only the anastomotic sites were included (OVH=12.2%, EVH=15.4%, P = .43). The length of hospital stay (LOS) was comparable between the two groups (EVH=8.73 ± 9.69, OVH=6.35 ± 3.28, P = .26) with no significant difference in the recovery time. Primary graft patency rate was 43.2% in the EVH group and 69.4% in the OVH group (P = .007) at 3 years. The most common reason for loss of primary patency was graft occlusion (61.5%) in OVH group and vein graft stenosis (54.5%) in the EVH group. The average number of vascular reinterventions per bypass graft was significantly lower in the OVH group compared to the EVH group (OVH=0.37, EVH= 1.28, P < .001).
Conclusions
Our findings demonstrate inferior primary patency when using the technique of EVH. Additionally, we identified a significantly higher rate of reintervention in the EVH cohort as well as a higher rate of vein graft body stenosis. However, EVH was associated with decreased rate of wound complications with similar limb salvage and secondary patency rates when compared to OVH. EVH should therefore be selectively utilized in patients at high risk for wound complications.
INTRODUCTION
Saphenous vein grafts have been established as the gold standard conduit for lower extremity bypass grafting 1. Conventionally, the great saphenous vein (GSV) is typically harvested via a long continuous or “skip” incisions that may extend from the groin to the ankle, before its use as an arterial conduit. This approach however is associated with significant morbidities including surgical site infections, ischemic skin flaps, fat necrosis, lymph leak, increased postoperative pain and longer hospital stay for as many as 24% to 43% of patients 2-3. Although these complications are reported extensively in the cardiac literature, wound complications in vascular patients are even further compounded by arterial and venous insufficiency, diabetes, and redo operations, conditions frequently exhibited by this patient population.
Minimally invasive vein harvesting techniques were initially introduced in 1994 and have been developed in order to reduce the wound morbidity associated with open vein harvest 4. Studies have shown reduced rates of postoperative wound complications, decreased hospital LOS, and reduced overall cost following EVH compared to traditional vein harvest 5-9.
The patency rates of lower extremity bypass grafts harvested endoscopically were initially reported to parallel that of standard open technique, with 5-year primary patency rates ranging from 51% to 73% and secondary patency from 68% to 81% 10-14. However recently, there have been multiple reports both in the cardiac as well as in the vascular surgery literature, showing inferior long-term patency rates and increased rates of interventions with endoscopic vein harvesting (EVH) 15-17. These reports either included short harvest segments for coronary grafting, or a heterogeneous vascular population of claudicants and CLI patients. On the basis of all these mixed and conflicting results, we reviewed our experience to evaluate differences in patency and to investigate differences in the mode of failure and rates of interventions, specifically in patients treated for critical limb ischemia (CLI).
METHODS
Patients
The study was reviewed and approved by the Institutional Review Board at the University of Pittsburgh. A retrospective analysis of consecutive patients undergoing lower extremity revascularization with saphenous vein grafts for critical limb ischemia at the University of Pittsburgh Medical Center between 2009 and 2011 was performed. 88 patients were identified of whom 39 underwent an infrainguinal bypass using endoscopic vein harvest (EVH) and 49 had an open vein harvest (OVH). Patients in the EVH group were mainly treated by one of the investigators (RC), who preferentially utilizes EVH on all comers, with no set selection criteria. Exclusion criteria included the use of spliced veins (5 patients in the EVH group and 4 patients in the OVH group), synthetic composite grafts, in addition to indication for bypass other than critical limb ischemia (CLI). This includes 7 patients in the EVH group (5 claudicants, 2 traumatic injury) and 12 patients in the OVH group (all claudicants).
Preoperative clinical characteristics, operative data and postoperative outcomes were collected and analyzed between the OVH and EVH groups. All patients in both groups underwent a preoperative duplex saphenous vein mapping to determine the quality and the suitability of the vein. A single experienced cardiac surgery physician assistant who routinely performs EVHs for CABGs for more than 10 years performed all EVHs (MK). All OVHs were done through a single long incision. The OVH control group included consecutive patients treated in the same time period for CLI, and were performed by a single vascular surgeon (SAL), usually with the assistance of a resident.
Surgical procedure
For endoscopic vein harvesting, patients were placed in a supine position and a transverse stab incision was made at the medial tibial condyle. Sharp dissection was then carried to identify the greater saphenous vein, which was then elevated with a vessel loop. Another stab incision was made in the groin to disconnect the saphenous vein from the saphenofemoral junction. In patients where the calf portion of the vein was also harvested by redirecting the catheter caudally, a separate stab incision was made at the medial calf to disconnect and ligate the vein distally. An ankle incision was not typically utilized. Endoscopic vein harvest was performed with the disposable VASOVIEW 7 Endoscopic Vessel Harvesting (EVH) System (Maquet Inc, Wayne, NJ, USA), using carbon dioxide insufflation technique (flow set at 5, and pressure of 12mm Hg) in the perivenous tunnel created by the camera dissector. Bipolar electric cautery (set at 25) was employed to divide side branches in situ with silk ties applied prior to grafting. During blunt tip dissection, a regular sequence of short gentle motions is performed, allowing the CO2 to promote dissection and ensuring that side branches are dissected thoroughly to allow adequate length for branch division. By providing an adequate margin and keeping electrocautery energy settings on the lowest possible settings, the risk of thermal injury is minimized. Once removed, the greater saphenous vein (GSV) is dilated and preserved with Plasma-lyte solution (Baxter International, Inc. Deerfield,IL) until ready to be used. All EVH procedures were performed by the same physician assistant who has performed over two hundred EVH cases. Saphenous vein grafts harvested using either technique, when used in non-reversed fashion, underwent a similar valvulotomy technique, using the Mills valvulotome.
Follow-up
Post-bypass, all patients were imaged either with an intraoperative completion angiogram or a Duplex ultrasound prior to discharge. Subsequent surveillance Duplex ultrasound and doppler studies were obtained at the first follow up visit, and every 3 to 6 month for the first postoperative year, then annually. If bypass grafts were judged to be at risk of failure, more frequent surveillance regimen was implemented at the discretion of the vascular surgeon. The surveillance protocol and threshold for intervention was similar in both groups and was based on our established vascular laboratory surveillance protocol.
Vein graft stenosis was determined based on physical examination and Duplex ultrasonography at each follow up visit. Worrisome physical examination findings (i.e. loss of graft pulsatility), or Duplex findings of a peak systolic velocity (PSV) > 200 cm/s, a velocity ratio (Vr) >3.0, a graft velocity < 35cm/s, or an ankle-brachial indices drop by >0.15, led to angiographic evaluation and possible re-intervention.
The primary patency rate was calculated from the date of last known graft patency as confirmed by duplex imaging or an ankle pressure previously known to correlate with a duplex-confirmed patent graft. Standard definition of primary, primary-assisted and secondary patency rates was utilized as previously described according to the Rutherford criteria 18. Primary patency was defined as the absence of restenosis, occlusion or re-intervention in the treated arterial segment. The primary patency for any intervention ended when there was clear evidence of occlusion on imaging, if there was a need for repeat endovascular intervention, surgical bypass, or major amputation. Primary-assisted patency for each intervention was achieved via repeat/secondary endovascular interventions to treat restenosis involving the originally treated arterial segment. Additional procedures to treat lesions proximal or distal to the initially treated segment were also considered secondary interventions to achieve primary assisted patency. Secondary patency for each intervention was achieved using repeat endoluminal intervention to recannalize occluded arterial segments or by performing open surgical bypass. Patency rates were calculated using Kaplan-Myer and log-rank test for significance.
Postoperative wound complications were classified using a modification of the Szilagyi's description. Concisely, class I wound infection is characterized by erythema requiring antibiotics treatment, class II wounds were defined with either drainage or superficial dehiscence and class III wounds were described as one with exposed or threatened grafts 19.
Statistics
Continuous data are presented as median with interquartile range. Categorical data are presented as frequency and percent. The groups were compared for significant differences by using the Chi-Square/Fisher's exact test for categorical data and Mann-Whitney U test for continuous data. Patency was analyzed by Kaplan-Meier survival curves with log Rank (Mantel-Cox) test. Categorical variables were tested for significance using the chi-squared test. All data were analyzed with the intention-to-treat principle. A P value of < .05 was considered significant. All analysis were conducted with SPSS 19.0 (SPSS Inc., Chicago, IL). All statistical analysis were performed by a biostatistician from the Clinical and Translational Science Institute (CTSI) at the University of Pittsburgh.
RESULTS
Patient Factors
From January 2009 to December 2011, 39 patients underwent lower extremity revascularization using EVH and 49 patients had OVH. Preoperative demographics and clinical characteristics of patients in both groups were comparable. Specifically, no significant differences were found in age, gender, race, body mass index, tobacco use (Table I), diabetes, baseline renal function, hypertension, hyperlipidemia, coronary artery disease and cerebrovascular accidents (Table II). All patients underwent lower extremity bypass surgery for critical limb ischemia (Table III). Patients routinely underwent vein mapping to determine the quality and vein size prior to the bypass surgery. Vein characteristics were not different in both groups with more than 75% of veins used were between 3 and 5mm in size. In addition, only 11.1% of veins used in the EVH group and 6.1% in the OVH group had limited varicose segments, as determined by preoperative duplex saphenous vein mapping. Preoperative ankle brachial index and toe pressures were also comparable (Table IV).
Table I.
Baseline demographic characteristics
| EVH (N=39) | OVH (N=49) | P value | |
|---|---|---|---|
| Age (years, mean, ± SD) | 70.9 ± 11.0 | 72.4 ± 11.6 | .55 |
| Gender (male no., %) | 25(67.6%) | 29(59.2%) | .43 |
| Race | |||
| White (no., %) | 35 (89.7%) | 44 (89.8%) | .69 |
| Black (no., %) | 2 (5.1%) | 5 (10.2%) | .34 |
| Other (no., %) | 2 (5.1%) | 0 (0%) | |
| BMI (mean ± SD) | 27.0 ± 5.5 | 27.7 ± 6.1 | .60 |
| Smoking status | |||
| Never (no., %) | 11 (29.7%) | 18 (36.7%) | .33 |
| Former (no., %) | 15 (40.5%) | 23 (46.9%) | .33 |
| Current (no., %) | 11 (29.7%) | 8 (16.3%) | .20 |
Table II.
Preoperative clinical characteristics
| EVH (N=39) | OVH (N=49) | P value | |
|---|---|---|---|
| Diabetes | 17 (45.9%) | 30 (61.2%) | .16 |
| Renal function | |||
| Chronic kidney disease | 3 (8.1%) | 10 (20.4%) | .12 |
| End stage renal disease | 1 (2.7%) | 3 (6.1%) | .63 |
| Hypertension | 30 (81.1%) | 44 (89.8%) | .25 |
| Hyperlipidemia | 26 (70.3%) | 30 (61.2%) | .38 |
| Coronary artery disease | 25 (67.6%) | 33 (67.3%) | .98 |
| Prior CABG | 7 (18.9%) | 11 (22.4%) | .69 |
| Congestive heart failure | 13 (35.1%) | 14 (28.6%) | .52 |
| Previous MI | 16 (43.2%) | 14 (28.6%) | .16 |
| Atrial fibrillation | 10 (27.0%) | 21 (42.9%) | .13 |
| COPD | 4 (10.8%) | 9 (18.4%) | .33 |
| Prior CVA/TIA | 10 (27.0%) | 12 (24.5%) | .79 |
| Neuropathy | 13 (35.1%) | 16 (32.7%) | .81 |
| Connective tissue disease | 2 (5.4%) | 1 (2.0%) | .58 |
| History of malignancy | 8 (21.6%) | 8 (16.3%) | .53 |
Table III.
Indications for Surgery
| EVH (N=39) | OVH (N=49) | P value | |
|---|---|---|---|
| Rest pain | 16 (41.0%) | 9 (18.4%) | .18 |
| Ulcer | 19 (48.7%) | 33 (67.3%) | .11 |
| Gangrene | 4 (10.3%) | 7 (14.3%) | .54 |
Table IV.
Vein characteristics and preoperative evaluation
| EVH (N=39) | OVH (N=49) | P value | |
|---|---|---|---|
| Vein size | .20 | ||
| <3mm | 4 (11.1%) | 10 (20.4%) | |
| 3-5mm | 27 (75%) | 37 (75.5%) | |
| >5mm | 5 (13.9%) | 2 (4.1%) | |
| Vein quality | .45 | ||
| Normal | 32 (88.9%) | 46 (93.9%) | |
| Varicose | 4 (11.1%) | 3 (6.1%) | |
| ABI | 0.60 ± 0.29 | 0.64 ± 0.48 | .41 |
| Toe pressures | 30.8 ± 29.8 | 21.3 ± 18.9 | .83 |
Operative Characteristics
Operative time was longer in the endoscopic harvest group (392.1 min ± 89.7) compared to the OVH group (195.6 min ± 57.5) (P < .001). The EVH was performed at the start of the case prior to anastomotic site exposure to avoid loss of gas insufflation. Estimated blood loss was comparable between the two groups (EVH = 214.9 ± 134.3; OVH = 284.7 ± 193.7; P = .02) with only 13.5% and 14.3% of patients, required intraoperative blood transfusions in the EVH and OVH groups respectively. Most bypasses were performed using the GSV in a non-reversed fashion (EVH=81.1%; OVH=61.3%). Only 1 patient had the lesser saphenous vein used and 1 patient had in-situ GSV, both in the OVH group. Bypass grafts were tunneled subcutaneously in both groups. Revascularization tended to be for more proximal lesions in the EVH group compared to the OVH group and often required femoral reconstruction as further detailed in table V. Additionally, patients in the EVH group were more likely to receive a completion intraoperative angiogram.
Table V.
Operative characteristics
| EVH (N=39) | OVH (N=49) | P value | |
|---|---|---|---|
| Surgery time (min) (mean ± SD) | 392.1 ± 89.7 | 195.6 ± 57.5 | < .001 |
| EBL (ml) (mean ± SD) | 214.9 ± 134.3 | 284.7 ± 193.7 | .02 |
| Intraop transfusion (no., %) | 5 (13.5%) | 7 (14.3%) | .92 |
| Conduit type | .14 | ||
| Reversed GSV | 7 (18.9%) | 17 (34.7%) | |
| Non-reversed GSV | 30 (81.1%) | 30 (61.3%) | |
| In-situ GSV | 0 (0%) | 1 (2%) | |
| LSV | 0 (0%) | 1 (2%) | |
| Vein tunneling | .10 | ||
| Anatomic | 8 (21.6%) | 23 (46.9%) | |
| Subcutaneous | 29 (78.4%) | 25 (51.0%) | |
| In situ | 0 (0%) | 1 (2%) | |
| Proximal anastomosis | .03 | ||
| Common femoral | 12 (30.7%) | 10 (20.4%) | |
| Superficial femoral | 12 (30.7%) | 7 (14.3%) | |
| Deep femoral | 5 (12.8%) | 7 (14.3%) | |
| Popliteal | 10 (25.6%) | 25 (51.0%) | |
| Distal anastomosis | .01 | ||
| Above knee popliteal | 4 (10.2%) | 3 (6.1%) | |
| Below knee popliteal | 13 (33.3%) | 7 (14.3%) | |
| Anterior tibial | 6 (15.3%) | 12 (24.5%) | |
| Posterior tibial | 4 (10.2%) | 1 (2.0%) | |
| Peroneal | 7 (17.9%) | 10 (20.4%) | |
| Pedal/Plantar | 5 (12.8%) | 16 (32.7%) |
Postoperative course and complications
Hospital LOS was not different between the 2 groups, with a mean hospital stay of 8.73 ± 9.69 days for the EVH and 6.35 ± 3.28 days for the OVH (P= .26). Although not statistically significant, EVH patients had a trend toward quicker recovery with more patients discharged to home while OVH patients were more likely to be discharged to skilled nursing facilities. No statistically significant difference was found between the two groups in the incidence of postoperative acute renal failure, myocardial infarction, cerebrovascular accidents, respiratory complications and death. One (2.0%) of 49 patients in the OVH group died of a presumed myocardial infarction on postoperative day 2 (Table VI).
Table VI.
30 –day outcomes
| EVH (N=39) | OVH (N=49) | P value | |
|---|---|---|---|
| Postop ABI | 0.94 ± 0.27 | 0.91 ± 0.27 | .98 |
| Postop toe pressures | 67.11 ± 32.1 | 49.6 ± 34.9 | .02 |
| Hospital stay | 8.73 ± 9.69 | 6.35 ± 3.28 | .26 |
| Postop disposition | .29 | ||
| Home | 26 (70.3%) | 29 (59.1%) | |
| Nursing facility | 11 (29.7%) | 20 (40.8%) | |
| Mortality | 0 (0%) | 1 (2.0%) | .57 |
| MI | 0 (0%) | 2 (4.2%) | .50 |
| Renal failure | 2 (5.4%) | 3 (6.3%) | 1.00 |
| Pneumonia | 1 (2.7%) | 0 (0%) | .44 |
| CVA/TIA | 0 (0%) | 1 (2.1%) | 1.00 |
| UTI | 1 (2.7%) | 2 (4.2%) | 1.00 |
| DVT | 0 (0%) | 0 (0%) | |
| Wound infections | |||
| Total | 6 (16.2%) | 11 (22.9%) | .31 |
| Vein harvest site | 0 (0%) | 10 (20.4%) | < .001 |
| Surgery site | 6 (15.4%) | 6 (12.2%) | .43 |
| Average # of interventions/graft | 1.28± 1.59 | 0.37 ± 0.85 | < .001 |
| Reason for graft failure | |||
| Inflow/outflow disease | 3 (13.7%) | 3 (21.4%) | .18 |
| Anastomotic stenosis | 2 (9.1%) | 3 (21.4%) | .05 |
| Mid-graft stenosis | 12 (54.5%) | 0 (0%) | < .001 |
| Graft occlusion | 5 (22.7%) | 8 (57.2%) | .04 |
| Major Amputations (BKA/AKA) | 1 (2.5%) | 4 (8.1%) | .34 |
Wound complications
Postoperative wound complications were characterized using a modification of the Szilagyi's classification. Overall, the total incidence of wound complications was 16.2% (6/39) in the EVH group and 22.9% (11/49) in the OVH group (P= .31) (Table VI). No patient developed stage III wound infection with associated threatened graft. Both groups had similar rate of wound infection at the anastomotic exposure site (EVH=15.4% vs. OVH=12.2%, P= .43) however the OVH group had a significantly higher wound infection rate at the vein harvest incision site (EVH=0% vs. OVH=20.4%, P < .001). Three of the 10 patients in the OVH group with vein harvest site wound infection had stage II wound infections requiring intravenous antibiotics and local wound care, and the rest only required oral antibiotics.
Reinterventions, patency, and limb salvage
One EVH (2.5%) patient and two OVH patients (4.1%) required operative intervention within the early postoperative period (<30 days) (P= .49). The EVH patient developed thrombosis of the graft on POD#1, requiring take back to the operating room for successful graft thrombectomy. The two OVH patients needed operative intervention for groin hematomas secondary to suture line bleeding with associated graft thrombosis. Late graft stenosis (>30days) was treated with percutaneous or operative interventions.19/39 patients in the EVH group and 8/49 patients in the OVH group had evidence of graft stenosis during the study period at a mean follow up of 22.8 months after the initial bypass. In the EVH group, 4 patients underwent open revision of their bypass grafts, 1 patient had a balloon angioplasty for a proximal stenosis and a simultaneous open jump graft for a severe distal lesion; the remaining (15) underwent successful endovascular interventions for severe stenosis identified on Duplex ultrasound imaging and confirmed by angiography. In the OVH group, 3/8 patients underwent endovascular interventions while the rest underwent open revision. Graft occlusions were also treated with percutaneous or operative interventions. Overall, 9 patients in the EVH group (23%) had evidence of graft occlusion compared to 8 patients (16.3%) in the OVH group. In the EVH group, percutaneous intervention was attempted and successful in 2 of the 9 patients, while 5 patients had surgical intervention with graft revision. 1 patient underwent a below knee amputation and 1 patient was found to have graft occlusion however did not require any intervention and was asymptomatic. In the OVH group, 4 patients underwent surgical revision of their bypass, 3 patients underwent a below knee amputation while 1 patient underwent an above knee amputation for an overwhelming soft tissue infection despite a patent graft. Table VII summarizes the interventions performed on failing grafts.
Table VII.
Management of failing grafts
| Primary/primary-assisted patency (No.,%) | Secondary patency (No.,%) | |||
|---|---|---|---|---|
| Interventions | EVH (19) | OVH (8) | EVH (9) | OVH (8) |
| Balloon angioplasty | 16 (41.0%) | 3 (6.12%) | 5 (12.8%) | 1 (2.04%) |
| Open surgical bypass | 1 (2.56%) | 2 (4.08%) | 3 (7.69%) | 3 (6.12%) |
| Patch angioplasty | 0 (0%) | 0 (0%) | 2 (5.12%) | 0 (0%) |
| Interposition graft | 2 (5.12%) | 3 (6.12%) | 3 (7.69%) | 0 (0%) |
| Thrombectomy | 1 (2.56%) | 0 (0%) | 3 (7.69%) | 2 (4.08%) |
| Observation | 0 (0%) | 1(2.04%) | 1 (2.56%) | 0 (0%) |
| Major amputation | 0 (0%) | 0 (0%) | 1 (2.56%) | 4 (8.16%) |
Patency rates were significantly better in the OVH compared to the EVH group. The primary patency rate was 43.2% in the EVH group and 69.4% in the OVH group at a mean follow-up of 30 months (P= .007) (Fig 1). At 30 months, the primary assisted patency was 75.7% in the EVH group and 100.0% in the OVH group (P= .001) (Fig 2), and secondary patency was 100.0% for the EVH group and 93.9% for the OVH group (P= .12) (Fig 3). In addition to differences in patency rates, both groups demonstrated significant disparities in the etiology of graft failure. The most common reason for loss of primary patency in the OVH group was graft occlusion (OVH = 57.2%, EVH=22.7%, P = .04), whereas the most common reason for loss of primary patency in the EVH group was mid-graft stenosis (EVH=54.5%, OVH=0%, P < .001). The average number of vascular reinterventions per bypass graft was significantly lower in the OVH group compared to the EVH group (OVH=0.37, EVH= 1.28, P < .001). Limb salvage rate was not different between the 2 groups with 1 patient (2.5%) in the EVH group and 4 patients (8.1%) in the OVH group undergoing major amputations following revascularization (P= .34) (Table VI).
Figure 1.
Comparison of primary patency between endoscopic vein harvest (EVH) and open vein harvest (OVH) by Kaplan-Meier survival analysis; P = .07.
Figure 2.
Comparison of primary-assisted patency between endoscopic vein harvest (EVH) and open vein harvest (OVH) by Kaplan-Meier survival analysis; P = .001.
Figure 3.
Comparison of secondary patency between endoscopic vein harvest (EVH) and open vein harvest (OVH) by Kaplan-Meier survival analysis; P = .117.
DISCUSSION
Endoscopic vein harvesting techniques have been developed in an attempt to decrease the morbidity associated with open vein harvest. This study reviews our experience over the past 3 years of patients undergoing lower extremity bypass surgery for critical limb ischemia with endoscopic versus open saphenous vein harvest. We found our results to partially support previously published findings. Consistent with previous studies, our study confirms that EVH was associated with decreased wound infection at the vein harvest site. However primary patency rates were significantly lower with an increased frequency of reinterventions in the EVH group compared to OVH. No difference in limb salvage or length of hospital stay was noted between the two groups.
Endoscopic vein harvesting was explored in the early 90s by cardiac surgeons and quickly became the standard of care for CABG. Multiple early reports in the cardiac literature have shown reduced postoperative morbidities and wound complications associated with EVH with no compromise on graft patency 20-21. By 2005, EVH was used in 80% of coronary bypasses in the United States 14. The situation was different for the vascular community for numerous reasons and currently, only about 10-20% of vascular surgeons utilize EVH for lower extremity bypass grafts 17. During a CABG procedure, both the cardiac surgeon and the assistant are able to operate simultaneously. This is distinctly different in lower extremity bypasses where vein harvesting occurs in the same physical space as the arterial exposure, rendering insufflation and seal challenging for EVH. The inability to simultaneously harvest vein and expose the anastomotic sites substantially increases operative time. In addition, any vein injury, either in the form of pressure, traction, burn or sharp trauma is more significant for the longer bypasses used in the extremities, which require a longer segment of harvested vein. On the other hand, in CABG, shorter vein length is satisfactory and focal injuries can be excluded and discarded. The use of harvesting techniques with no insufflation developed to minimize some of the above problems, also presents inherent hurdles. Although they minimize complications associated with increased OR time and potential injury to the vein from insufflation pressure, such techniques may be limited by less visualization and exposure. This may require additional traction on the vein for optimal exposure potentially resulting in increased vein injury and reduced graft patency.
In contrast to the abundant evidence demonstrating the short-term and wound related complications after EVH, there is paucity of data regarding graft patency or clinical outcomes comparing both modalities. While earlier studies reported comparable patency rates and outcomes following EVH, there have been a number of recent reports showing reduced graft patency following EVH when compared to the traditional open technique. Two recent studies looked at short- and long-term outcomes of lower extremity bypasses using saphenous veins harvested either endoscopically or open. They showed inferior patency rates for endoscopically harvested saphenous veins after LEBP without confirming the short-term benefits previously reported, specifically length of hospital stay and wound complications rates 15, 17. Even more surprisingly, two recent reports in the cardiac literature by Lopes et al. and Zenati et al. showed also similar results 16, 22. Disputing earlier reports, they demonstrated inferior graft patency with associated increased need for repeat revascularization, occurrence of myocardial infarction and death in patients undergoing endoscopic harvest. Our results were comparable and further support those reports. While our results showed improved wound complications rates at the vein harvest site, other short-term outcomes such as 30-day mortality and morbidities were comparable between both groups. In addition, the previously reported impact of EVH on improved recovery was not evident in our study, even though both groups were comparable in terms of social support and co-morbidities. A larger cohort study may be needed to better evaluate the impact of harvesting techniques on recovery period and length of hospital stay. More significantly, patients undergoing EVH were more susceptible to graft failure and required increased rates of interventions. In addition, our study provides novel evidence on the pattern of graft failure following lower extremity bypass using different harvesting techniques, specifically in the EVH group. While it has been previously known that graft failure occurs commonly at the anastomotic sites, we provide convincing evidence that patients undergoing EVH have a significantly higher rate of vein body stenosis compared to OVH (Fig. 4). These results highlights the potential risk associated with EVH, which has been alluded to in other reports 23-25.
Figure 4.
Representative angiogram of two different bypass grafts harvested endoscopically with stenosis in the body of the vein. Arrows are pointing to the area of stenosis.
Critics of EVH argue that this technique causes significant trauma to the vein. Although early studies showed no signs of intimal injury on histology 26, recent evidence using multiphoton imaging and immunofluorescence staining suggested evidence of structural and functional impairment of endothelial cells, leading to graft failure 23-25. EVH commonly requires insufflation in addition to bipolar cautery in the vicinity of the vein, both of which are not required in OVH. Thermal energy has been proposed to cause injury to the vessel wall and impair the quality of the graft by damaging the endothelial cells leading to intimal hyperplasia and graft stenosis. Traction may also be associated with significant mechanical injury to the vein graft. This is somewhat supported by our findings that graft stenosis in the EVH group was more commonly seen in the body of the bypass graft, likely at the site of cauterization of large branches, whereas in the OVH group, it was more localized to the anastomosis, which is what has been traditionally described as a cause of graft stenosis and failure. It is noteworthy that despite the inferior patency rates observed in the EVH group, limb salvage and amputation-free survival was similar between the two groups. This was compensated for by increased open and endovascular interventions, more commonly in the EVH group. Graft salvage was made possible by close surveillance in the postoperative period and aggressive interventions when warranted. Although not addressed in our current study or other previous reports, this potentially leaves a role and value for EVH in specific situations or patient population at high risk for wound morbidity with OVH, and should not be completely abandoned, particularly for morbidly obese patients, re-operative fields, and contralateral leg harvest 27-28. Furthermore, since its introduction in the mid-90s, EVH has undergone many transformations with both refinement in the harvesting technique and vessel handling, in addition to technological advancement with easier and more protective features. New generations EVH systems have been developed to minimize endothelial cell damage secondary to “thermal spread”. They use bipolar radiofrequency energy source and are designed to keep thermal spread to a minimum (less than 1mm), potentially minimizing graft injury. However, to date, data is still lacking comparing different harvesting systems and technologies. The results of this study have the authors to adopt this selective use of EVH in their practice for such high risk patients, and have prompted the adoption of newer generation EVH systems.
In this retrospective study, several methods were used to control for potentially confounding factors, which were not addressed in previous reports. While the learning curve for endoscopic vein harvest was a concern in multiple previous studies, only a single experienced physician assistant performed all the EVH in this study. Moreover, all OVH were performed by a single surgeon, potentially further controlling for interpersonal variabilities. Furthermore, differences in conduit caliber and quality were carefully evaluated and controlled for between the 2 groups, another critical confounding variable frequently not addressed in the literature. As previously mentioned, all patients in our study underwent preoperative vein mapping to assess the size and quality of the vein, and were comparable between the 2 groups. On the other hand, few variables were different in our study. While operative time was similar in previous reports when comparing both harvesting techniques 27 our study had significantly longer operative time for the EVH group. Besides the inability to work simultaneously during the endoscopic vein harvest, a significant percentage of patients (9/39) in the EVH group who had more proximal disease underwent simultaneous femoral endarterectomy at the time of the procedure, adding further to the operative time. In addition, the bypasses done in the OVH group were shorter, and less frequently accompanied by a completion angiogram, also diminishing the operative time.
This study has certain caveats and limitations that should be considered. This is a retrospective single center study, which can allow for bias from unmeasured confounders. In addition, patients in both groups were not randomized, and selection of the harvest technique was based upon the single surgeon's preference, possibly introducing a selection bias despite the routine use of one technique or the other on all comers by the investigators. In addition to selection bias, operator bias provides another limitation to this study. However, we do not believe that differences in graft patency are due solely to operator differences. Vascular surgeons participating in this study utilize similar exposure, tunneling, hemostasis and suturing techniques and have previously established comparable graft patency rates. This leaves methods of vein harvesting a major contributing factor to differences in outcomes in our study. However, despite both groups being comparable in major risk factors, inter-operator variability may still introduce a systematic error to the final analysis. Furthermore, the sample size is small and could limit our ability to highlight or identify small differences. Another factor that may theoretically affect our results and analysis is that bypasses in the OVH group were more commonly from the popliteal to tibial or pedal vessels with potentially shorter overall length of grafts compared to the bypasses in the EVH group. The importance of economic ramifications of each harvesting technique was also not addressed in our study. EVH may be associated with additional costs in our study such as increased operative time, equipment cost, and increased reinterventions; however a more complete cost analysis should be performed with a larger cohort study to be able to establish the cost effectiveness of each harvesting technique. Despite these limitations, this study provides valuable novel data looking at the mid-term outcomes and patency of grafts harvested endoscopically compared to open techniques.
CONCLUSION
In conclusion, this study shows that although EVH may be associated with decreased rate of wound complications, it is associated with inferior graft patency in patients treated for CLI with an increased incidence of severe stenosis within the body of the graft requiring reintervention. However, limb salvage and secondary patency rates are similar. EVH should therefore be selectively utilized in patients at high risk for wound complications.
ACKNOWLEDGEMENTS
We would like to thank the Clinical and Translational Science Institute (CTSI) at the University of Pittsburgh for the assistance in the statistical analysis. The project described was supported by the National Institutes of Health through Grant Numbers UL1RR024153 and UL1TR000005.
Footnotes
Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Presented at the Eastern Vascular Society Meeting, September 2012, Pittsburgh PA. Oral presentation.
REFERENCES
- 1.Pereira CE, Albers M, Romiti M, Brochado-Neto FC, Pereira CA. Meta-analysis of femoropopliteal bypass grafts for lower extremity arterial insufficiency. J Vasc Surg. 2006;44:510–7. doi: 10.1016/j.jvs.2006.04.054. [DOI] [PubMed] [Google Scholar]
- 2.Kent KC, Bartek S, Kuntz KM, Anninos E, Skillman JJ. Prospective study of wound complications in continuous infrainguinal incisions after lower limb arterial reconstruction: incidence, risk factors, and cost. Surgery. 1996;119:378–383. doi: 10.1016/s0039-6060(96)80135-8. [DOI] [PubMed] [Google Scholar]
- 3.Wengrovitz M, Atnip RB, Gifford RRM, Neumyer MM, Heitjan DF, Thiele BL. Wound complications of autogenous subcutaneous infrainguinal arterial bypass surgery: prediposing factors and management. J Vasc Sur. 1990;11:156–63. doi: 10.1067/mva.1990.16918. [DOI] [PubMed] [Google Scholar]
- 4.Lumsden AB, Eaves FF III, Ofenloch JC, Jordan WD. Subcutaneous, video-assisted saphenous vein harvest: report of the first 30 cases. Cardiovasc Surg. 1996;4:771–776. doi: 10.1016/s0967-2109(96)00055-5. [DOI] [PubMed] [Google Scholar]
- 5.Baddour LM, Bisno AL. Recurrent cellulitis after coronary bypass surgery. JAMA. 1984;251:1049–52. [PubMed] [Google Scholar]
- 6.Greenberg J, DeSanctis RW, Mills RM, Jr, Vein-Wengrovitz M, Atnip RB, Gifford RRM, Neumyer MM, Heitjan DF, Thiele BL. Wound complications of autogenous subcutaneous infrainguinal arterial bypass surgery: prediposing factors and management. J Vasc Surg. 1990;11:156–63. doi: 10.1067/mva.1990.16918. [DOI] [PubMed] [Google Scholar]
- 7.Illig KA, Rhodes JM, Sternbach Y, Shortell CK, Davies MG, Green RM. Reduction in wound morbidity rates following endoscopic saphenous vein harvest. Ann Vasc Surg. 2001;15:104–109. doi: 10.1007/s100160010005. [DOI] [PubMed] [Google Scholar]
- 8.Illig KA, Rhodes JM, Sternbach Y, Green RM. Financial impact of endoscopic vein harvest for infrainguinal bypass. J Vasc Surg. 2003;37:323–330. doi: 10.1067/mva.2003.2. [DOI] [PubMed] [Google Scholar]
- 9.Black EA, Campbell K, Channon KM, Ratnatunga C, Pillai R. Minimally invasive vein harvesting significantly reduces pain and wound morbidity. Euro J Cardiothorac Surg. 2002;22:381–386. doi: 10.1016/s1010-7940(02)00296-8. [DOI] [PubMed] [Google Scholar]
- 10.Jordan WD, Alcocer F, Voellinger DC, Wirthlin DJ. The durability of endoscopic saphenous vein grafts: a 5-year observational study. J Vasc Surg. 2001;34:434–439. doi: 10.1067/mva.2001.117997. [DOI] [PubMed] [Google Scholar]
- 11.Erdoes LS, Milner TP. Encouraging results with endoscopic vein harvest for infrainguinal bypass. J Vasc Surg. 2005;42:442–8. doi: 10.1016/j.jvs.2005.05.008. [DOI] [PubMed] [Google Scholar]
- 12.Gazoni LM, Carty R, Skinner J, Cherry KJ, Harthun NL, Kron IL, et al. Endoscopic versus open saphenous vein harvest for femoral to below the knee arterial bypass using saphenous vein graft. J Vasc Surg. 2006;44(2):282–7. doi: 10.1016/j.jvs.2006.03.047. [DOI] [PubMed] [Google Scholar]
- 13.Hines GL, Wain RA, Montecalvo J, Feuerman M. Femoral-popliteal bypass with endoscopically harvested saphenous vein in patients with TASC D disease of the superficial femoral artery. Ann Vasc Surg. 2010;24(5):615–20. doi: 10.1016/j.avsg.2009.07.023. [DOI] [PubMed] [Google Scholar]
- 14.Dacey LJ, Braxton JH, Jr, Kramer RS, Schmoker JD, Charlesworth DC, Helm RE, et al. Long-term outcomes of endoscopic vein harvesting after coronary artery bypass grafting. Circulation. 2011;123(2):147–53. doi: 10.1161/CIRCULATIONAHA.110.960765. [DOI] [PubMed] [Google Scholar]
- 15.Pullat R, Brothers TE, Robison JG, Elliott BM. Compromised bypass graft outcomes after minimal-incision vein harvest. J Vasc Surg. 2006;44:289–295. doi: 10.1016/j.jvs.2006.02.072. [DOI] [PubMed] [Google Scholar]
- 16.Lopes RD, Hafley GE, Allen KB, Ferguson TB, Peterson ED, Harrington RA, et al. Endoscopic versus open vein-graft harvesting in coronary-artery bypass surgery. N Engl J Med. 2009;361:235–244. doi: 10.1056/NEJMoa0900708. [DOI] [PubMed] [Google Scholar]
- 17.Julliard W, Katzen J, Nabozny M, Young K, Glass C, Singh MJ, et al. Long-term results of endoscopic versus open saphenous vein harvest for lower extremity bypass. Ann Vasc Surg. 2011;25(1):101–7. doi: 10.1016/j.avsg.2010.10.013. [DOI] [PubMed] [Google Scholar]
- 18.Rutherford RB, Baker JD, Ernst C, Johnston KW, Porter JM, Ahn S, et al. Recommended standards for reports dealing with lower extremity ischemia: revised version. J Vasc Surg. 1997;26:517–538. doi: 10.1016/s0741-5214(97)70045-4. [DOI] [PubMed] [Google Scholar]
- 19.Szilagyi DE, Smith RF, Elliott JP, Vrandecic MP. Infection in arterial reconstruction with synthetic grafts. Ann Surg. 1972;176:321–333. doi: 10.1097/00000658-197209000-00008. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 20.Yun KL, Wu Y, Aharonian V, Mansukhani P, Pfeffer TA, Sintek CF, Kochamba GS, Grunkemeier G, Khonsari S. Randomized trial of endoscopic versus open vein harvest for coronary artery bypass grafting: six-month patency rates. J Thorac Cardiovasc Surg. 2005 Mar;129(3):496–503. doi: 10.1016/j.jtcvs.2004.08.054. [DOI] [PubMed] [Google Scholar]
- 21.Allen K, Cheng D, Cohn W, Connolly M, Edgerton J, Falk V, Martin J, Ohtsuka T, Vitali R. Endoscopic Vascular Harvest in Coronary Artery Bypass Grafting Surgery: A Consensus Statement of the International Society of Minimally Invasive Cardiothoracic Surgery (ISMICS) 2005. Innovations (Phila) 2005;1(2):51–60. doi: 10.1097/01.gim.0000196315.32179.82. Winter. [DOI] [PubMed] [Google Scholar]
- 22.Zenati MA, Shroyer AL, Collins JF, Hattler B, Ota T, Almassi GH, et al. Impact of endoscopic versus open saphenous vein harvest technique on late coronary artery bypass grafting patient outcomes in the ROOBY (Randomized On/Off Bypass) Trial. J Thorac Cardiovasc Surg. 2011;141(2):338–44. doi: 10.1016/j.jtcvs.2010.10.004. [DOI] [PubMed] [Google Scholar]
- 23.Black EA, Guzik TJ, West NEJ, Campbell K, Pillai R, Ratnatunga C, et al. Minimally invasive saphenous vein harvesting: effects on endothelial and smooth muscle function. Ann Thorac Surg. 2001;71:1503–7. doi: 10.1016/s0003-4975(01)02463-8. [DOI] [PubMed] [Google Scholar]
- 24.Rousou LJ, Taylor KB, Lu XG, et al. Saphenous vein conduits harvested by endoscopic technique exhibit structural and functional damage. Ann Thorac Surg. 2009;87:62–70. doi: 10.1016/j.athoracsur.2008.08.049. [DOI] [PubMed] [Google Scholar]
- 25.Hussaini BE, Lu XG, Wolfe JA, Thatte HS. Evaluation of endoscopic vein extraction on structural and functional viability of saphenous vein endothelium. J Cardiothorac Surg. 2011;6:82. doi: 10.1186/1749-8090-6-82. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 26.Meyer DM, Rogers TE, Jessen ME, Estrera AS, Chin AK. Histologic evidence of the safety of endoscopic saphenous vein graft preparation. Ann Thorac Surg. 2000;70:487–91. doi: 10.1016/s0003-4975(00)01503-4. [DOI] [PubMed] [Google Scholar]
- 27.Bonde P, Graham AN, MacGowan SW. Endoscopic vein harvest: advantages and limitations. Ann Thorac Surg. 2004;77:2076–2082. doi: 10.1016/j.athoracsur.2003.11.001. [DOI] [PubMed] [Google Scholar]
- 28.Caprino PA, Khabbaz KR, Bojar RM, Rastegar H, Warner KG, Murphy RE, Payne DD. Clinical benefits in patients with risk factors for saphenectomy wound infections undergoing coronary artery bypass grafting. J Thorac Cardiovasc Surg. 2000 Jan;119(1):69–75. doi: 10.1016/s0022-5223(00)70219-4. [DOI] [PubMed] [Google Scholar]