Patency and limb salvage for polytetrafluoroethylene bypasses with vein interposition cuffs

Safety of limb-salvaging surgery for sarcomas compromising major vessels: A 15-year single-centre outcomes study

INTRODUCTION

Limb-threatening sarcomas invading major vessels present an oncological and reconstructive challenge. Curative resection involves either performing an amputation or an immediate reconstruction of the invaded vessels. We present our 15-year experience of these cases at the North of England Bone and Soft Tissue Tumour Service.

MATERIALS AND METHODS

A Strengthening the Reporting of Observational studies in Epidemiology (STROBE) compliant retrospective review of our prospective database was performed including patients who required major vessel reconstruction following sarcoma excision from 2003 until 2018. Patient demographic data along with tumour and histological subtypes, treatment modality, complications and outcomes were inquired. Autologous and prosthetic vessel reconstruction approaches were compared.

RESULTS

Nineteen patients were identified with the most common tumour locations being the thigh and groin areas. Five cases involved recurrent tumours. Clear resection margins were obtained in 15 cases. Autologous vein grafts were preferred over polytetrafluoroethylene (PTFE) prosthesis in 17 cases. A pedicled flap or free flap was required to achieve adequate soft tissue cover in six patients, while the rest underwent primary closure. Five patients lost the patency of the reconstructed vessels with one of these requiring an amputation. The estimated disease-specific survival at 5 years was 58%.

DISCUSSION

Limb-preservation surgery in the context of vessel compromise is not only safe, but also a functionally and psychosocially beneficial means of avoiding an amputation. We believe that careful pre-operative planning and discussion in a multidisciplinary setting is key for obtaining positive outcomes.

Long-Term Results of Infrapopliteal Bypass Using Polytetrafluoroethylene and Taylor Vein Patch for Critical Lower Extremity Ischemia

Although distal anastomotic vein patch and cuff techniques have been advocated to improve the patency of lower extremity bypass grafts with polytetrafluoroethylene (PTFE), use of this approach in the infrapopliteal position remains unproven. The purpose of this study is to evaluate the results of infrapopliteal bypass grafting using PTFE and Taylor vein patch for critical lower extremity ischemia. All patients undergoing infrapopliteal bypass grafting with PTFE and Taylor vein patch for ischemic rest pain or tissue loss were identified from the vascular surgery registry. This report describes results for surgical morbidity and mortality, patency, limb salvage, and survival for procedures performed from 1993 through 1998. Forty-two infrapopliteal bypass grafts with PTFE and Taylor vein patch were placed for critical lower extremity ischemia during the 6-year period. Surgical indications were rest pain in 25 (60%) patients and ischemic tissue loss in 17 (40%). Distal arterial anastomosis included 17 (40%) anterior tibial, 10 (24%) peroneal, eight (19%) posterior tibial, and seven (17%) tibioperoneal arteries. Follow-up ranged from 1 to 52 months (mean 17 months). Life-table primary patency, secondary patency, limb salvage, and survival at 3 years were 25%, 31%, 44%, and 66%, respectively. Infrapopliteal bypass with PTFE and Taylor vein patch for critical lower extremity ischemia has poor long-term results that are comparable to those reported for PTFE without Taylor vein patch.

Systematic review and meta-analysis of vein cuffs for below-knee synthetic bypass

BACKGROUND

The aim was to investigate the possible benefit of vein cuffs for femoral to below-knee popliteal and femorodistal vessel synthetic bypass grafts.

METHODS

PubMed, the Cochrane library, Embase and ClinicalTrials.gov were searched for all studies on any clinical effect of vein cuffs on synthetic grafts. Outcomes were selected based on inclusion in two or more studies: primary patency and limb survival. The data were subjected to meta-analysis by outcome.

RESULTS

Three cohort and two randomized studies were selected for inclusion, involving 885 patients. Meta-analysis of five studies examining below-knee popliteal bypass showed a significant improvement for primary patency in cuffed grafts at 2 years, but not at 1 or 3 years (odds ratio at 2 years 0·46, 95 per cent confidence interval 0·22 to 0·97; P = 0·04). Limb salvage was significantly improved in cuffed grafts up to 2 years. Limb survival was also improved for cuffed distal grafts at 2 years (odds ratio 0·29, 0·11 to 0·75; P = 0·01) but showed no difference at any other time interval. Study quality was generally poor, with conflicting results.

CONCLUSION

There was a small but significant benefit for vein cuffs on synthetic grafts used for femoral to below-knee popliteal anastomoses, but little benefit for femorodistal anastomoses.

Revascularization of a specific angiosome for limb salvage: does the target artery matter?

Ischemic wounds of the lower extremity can fail to heal despite successful revascularization. The foot can be divided into six anatomic regions (angiosomes) fed by distinct source arteries arising from the posterior tibial (three), anterior tibial (one), and peroneal (two) arteries. This study investigated whether bypass to the artery directly feeding the ischemic angiosome had an impact on wound healing and limb salvage. Retrospective analysis was performed for 52 nonhealing lower extremity wounds (48 patients) requiring tibial bypass over a 2-year period. Preoperative arteriograms were reviewed to determine arterial anatomy relative to each wound's specific angiosome and bypass anatomy. Patients were divided into two groups; direct revascularization (DR, bypass to the artery directly feeding the ischemic angiosome) or indirect revascularization (IR, bypass unrelated to the ischemic angiosome). Wound outcome was analyzed with regard to the endpoints of complete healing, amputation, or death unrelated to the wound. Time to healing was also noted for healed wounds. Based on preoperative arteriography, 51% (n = 27) of the wounds received DR to the ischemic angiosome, while 49% (n = 25) underwent IR. There were no statistically significant differences in the comorbidities of the two groups. Revascularization was via tibial bypass using the saphenous vein (n = 34, 65%) or polytetrafluoroethylene with a distal vein patch (n = 18, 35%). Bypasses were performed to the anterior tibial (n = 22, 42%), posterior tibial (n = 17, 33%), or peroneal (n = 13, 25%) arteries based on the surgeon's judgment. One bypass failed in the perioperative period and was excluded from the analysis. The remaining bypasses were patent at the time of wound analysis. Due to a 17% mortality rate during follow-up, 43 wounds were available for endpoint analysis. This analysis demonstrated that 77% of wounds (n = 33) progressed to complete healing and 23% of wounds (n = 10) failed to heal with resultant amputation. In the DR group, there was 91% healing with a 9% amputation rate. In the IR group, there was 62% healing with a 38% amputation rate (p = 0.03). In those wounds that did heal, total time to healing was not significantly different--DR 162.4 days versus IR 159.8 days (p = 0.95). Revascularization plays a crucial role in the treatment of ischemic lower extremity wounds. We believe that direct revascularization of the angiosome specific to the anatomy of the wound leads to a higher rate of healing and limb salvage. Although many factors must be considered in choosing the target artery for revascularization, consideration should be given to revascularization of the artery directly feeding the ischemic angiosome.

Early Results for Below-Knee Bypasses Using Distaflo

In patients who require lower extremity revascularization, prosthetic graft is a reasonable alternative in the absence of a suitable autologous vein conduit. However, prosthetic bypass grafts have limited patency, especially for infrageniculate reconstruction. Polytetrafluoroethylene grafts were geometrically modified at the distal end to increase their patency. The authors reviewed their experience with the Distaflo graft in patients who required lower extremity below-knee popliteal and tibial bypasses when no suitable autologous vein conduit was available. Chart review was conducted of the 57 patients who underwent 60 lower extremity bypasses over a 3-year period between June 2003 and April 2006. Twenty-four revascularizations were constructed to the tibial outflow sites, whereas the remaining grafts were placed to the below-knee (28) and above-knee (8) popliteal artery, respectively. Study endpoints were primary, assisted primary, secondary patency, and limb salvage at the time of follow-up. Distaflo bypass was performed at the infrageniculate level in 86.7% of cases (28 below-knee popliteal, 24 tibial). Mean follow-up time was 12 months (range, 0.5-37.5 months). At 1 year, primary, assisted primary, and secondary patencies and limb salvage rates for below-knee popliteal bypasses were 83.5%, 89.5%, 94.7%, and 94.4%, respectively. Primary, assisted primary, and secondary patencies and limb salvage rates for tibial bypasses were 44.4%, 44.4%, 63.2%, and 74.9%, respectively. Distaflo precuffed graft is a good alternative conduit for below-knee popliteal and tibial lower extremity reconstructions in the absence of an autologous vein and appears to have promising early patency and limb salvage rates even when used for tibial bypasses.

Infragenicular Bypass Graft for Limb Salvage Using Polytetrafluoroethylene and Distal Vein Cuff as the First Alternative in Patients Without Ipsilateral Greater Saphenous Vein

The objectives of this study were to evaluate the results of polytetrafluoroethylene infragenicular bypass grafts with a distal interposition vein cuff in patients with critical limb ischemia in the absence of ipsilateral greater saphenous vein. From January 1997 to June 2002, 58 consecutive below-knee bypass grafts with PTFE and distal interposition vein cuff were performed in 57 patients with a median age of 70.8 years. The distal anastomosis was located at the infragenicular popliteal artery in 18 cases and at tibial vessels in 40. Primary patency, secondary patency, and limb salvage were analyzed using the Kaplan-Meier method. During a median follow-up of 14.4 months (range, 1-50) 26 cases of graft occlusion and 19 major amputations were registered. The primary and secondary patency rates at 12, 24, and 36 months were 57%, 54%, and 47% and 61%, 58%, and 50%, respectively. Limb salvage rates reached 69%, 69%, and 59% at 12, 24, and 36 months. When below-knee revasculanzation is required in patients with limb-threatening ischemia, in the absence ipsilateral greater saphenous vein, PTFE grafts with a distal vein cuff are a reasonable substitute with acceptable long-term patency and limb salvage rates.

Experimental comparison of four methods of end-to-side anastomosis with expanded polytetrafluoroethylene

Background

Four established techniques of distal end-to-side anastomosis (direct anastomosis, Linton patch, Taylor patch and Miller cuff) were compared to investigate the local distribution of anastomotic intimal hyperplasia. The study aimed to elucidate whether mechanical factors or flow alterations are mainly responsible for the improved patency rates reported for vein cuff interposition techniques in infrainguinal arterial reconstructions using prosthetic graft material.

Methods

Thirty-two expanded polytetrafluoroethylene (ePTFE) femoropopliteal bypass grafts were implanted in 16 sheep using the four anastomotic techniques. After 6 months the grafts were explanted and examined histologically. The local distribution of intimal hyperplasia was determined, particularly for areas of material transition and of high and low shear stress.

Results

The mean amount and distribution of intimal hyperplasia were similar for all anastomotic types. Intimal hyperplasia was greatest along all transitions between ePTFE and venous patches, and between ePTFE and recipient artery. It was lower along the transitions between venous patches and artery, and was lowest at the host artery floor.

Conclusion

Vein interposition did not reduce anastomotic intimal hyperplasia and did not change the distribution patterns of hyperplasia, which were influenced mainly by mechanical factors. The effect of vein interposition is to move areas of maximum intimal hyperplasia away from the small recipient artery up to the more capacious graft-patch anastomosis.

On the Existence of an Optimum End-to-side Junctional Geometry in Peripheral Bypass Surgery—A Computer Generated Study

BACKGROUND

To investigate hemodynamic flow changes associated with vein cuffs and patches that may be responsible for improved patency of prosthetic infrainguinal grafts.

METHODS

The role of the graft-artery junction angle was examined by computational fluid dynamics to assess the influence of anastomotic geometry on wall shear stress (WSS) distributions. Three geometrically different junction configurations were studied and the WSS and WSS gradient (WSSG) values were compared.

RESULTS

The inclusion of a patch or a cuff moves the bed stagnation point (BSP) distally, increasing the area on the bed of the junction which experiences a BSP and reducing the strength of the recirculation region opposite the heel of the junction by 54.8 and 50.8%, respectively. The patched geometry promotes earlier recovery of the flow in the distal outflow segment (DOS) than for the unpatched model. Also, the helical flow patterns in the DOS associated with the cuffed geometry are stronger. The net effect of these changes are that peak WSSG values for the patched and cuffed geometries are three times lower than those for the uncuffed geometry.

CONCLUSION

This study provides some additional insights into the hemodynamics of graft-artery junction geometry which may influence future clinical practice.

Meta-analysis of polytetrafluoroethylene bypass grafts to infrapopliteal arteries

CONTEXT

Reports of polytetrafluoroethylene (PTFE) bypass grafting to the infrapopliteal arteries have often used survival analysis of acceptable quality to describe a wide range of long-term results. In theory, these results may be combined if variability between series and time intervals is considered.

OBJECTIVE

Meta-analysis was performed to gain insight into long-term graft patency and foot preservation after PTFE bypass grafting to infrapopliteal arteries.

DATA SOURCE

Studies published from 1982 through 2001 were identified from the PubMed database and pertinent original articles.

STUDY SELECTION

Three investigators selected 43 studies that used survival analysis, reported 2-year patency rates, and included at least 15 bypass procedures. Data extraction and transformation: Based on standard life-tables or survivor curves, an interval success rate was calculated for each month in each series. The monthly success rates were combined across series, enabling construction of pooled survivor curves.

DATA SYNTHESIS

Random-effects meta-analysis yielded 5-year pooled estimates (SE) of 30.5% (7.6%) for primary graft patency, 39.7% (5.5%) for secondary graft patency, and 55.7% (5.0%) for foot preservation. During the entire follow-up, pooled estimates were slightly higher for series of PTFE grafts with adjunctive procedures compared with series of PTFE grafts only. Sensitivity analysis: A simulation using only unfavorable assumptions showed a decrease of less than 5% at 5 years for all outcomes, and smaller differences at subgroup meta-analysis. Funnel plots suggested that publication bias was unlikely.

CONCLUSION

This meta-analysis indicated moderate success for PTFE bypass grafts to infrapopliteal arteries, but the role of adjunctive procedures at the distal anastomosis remains uncertain.

Long-term results of infrageniculate bypass grafting using all-autogenous composite vein

Infrageniculate (below-knee) bypass using all-autogenous composite vein requires multiple incisions, venovenostomy, and prolonged operating time. The purpose of this study was to evaluate the long-term results of this procedure, with comparisons to grafts created from single-segment greater saphenous vein (GSV) or polytetrafluoroethylene (PTFE). A total of 362 consecutive infrainguinal bypass grafts with infrageniculate distal target arteries were created in 283 patients in a single institution between January 1995 and December 2000. Comorbid conditions were common, including diabetes (58%), coronary artery disease (56%), prior lower extremity revascularization (41%), end-stage renal failure (20%), and prior coronary artery bypass grafting (18%). The indication for revascularization was limb salvage in 93% of cases. The grafts were constructed from single segments of GSV (n = 239), from two or more vein segments resulting in an all-autogenous composite graft (n = 61), or from PTFE (n = 62). All-autogenous composite grafts were constructed using segments of ipsilateral or contralateral GSV (n = 49), upper extremity vein (n = 23), superficial femoral vein (n = 7), or lesser saphenous vein (n = 5). Infrageniculate all-autogenous composite vein grafts exhibited similar long-term results to those of GSV grafts, and far superior results to those of PTFE grafts. For patients with available autogenous segments, the all-autogenous composite vein graft is the conduit of choice.

Tibial bypass using complex autologous conduit: patency and limb salvage

Over an 8-year period, we performed 93 lower extremity bypasses using complex autologous conduits, which included (1) contralateral greater saphenous vein (GSV), (2) composite GSV, (3) superficial femoral vein, (4) lesser saphenous vein, (5) cephalic or basilic veins, and (6) composite-sequential (PTFE and vein) grafts. These grafts represented 16% of all infrainguinal bypasses during this period, and all grafts were performed to treat limb-threatening ischemia. Survival, patency, and limb salvage were examined by the life-table method. Primary graft patency was 46 and 38% at 3 and 5 years. Assisted-primary patency was 62 and 59%, and secondary graft patency rates were 68 and 64% at 3 and 5 years. Twenty-nine bypasses (31%) required revision to restore or maintain patency. The 3-year limb salvage rate was significantly better when revision was performed for graft stenosis than for graft thrombosis (90% vs. 46%, p < 0.05). Overall limb salvage rate was 73% at 5 years. The mortality rate was 5.4% and the 5-year survival was 51%. Complex autologous tibial bypasses provided acceptable long-term limb salvage in patients with severe ischemia and inadequate ipsilateral GSV. The increased operating time and complexity required did not produce prohibitive operative risks. Postoperative graft surveillance in these complex vein bypasses allowed revision in many cases before graft occlusion occurred and significantly improved long-term limb salvage.

Tibial bypass for limb salvage using polytetrafluoroethylene and a distal vein patch

OBJECTIVE

Tibial artery bypass for limb salvage may be required in patients without adequate autogenous vein. The interposition of venous tissue at the distal anastomosis has been advocated to improve the results of prosthetic grafts to tibial arteries. Having reported on technical feasibility and an early experience with polytetrafluoroethylene (PTFE) and a distal vein patch (DVP), we examine the results of this technique with 4-year follow-up.

METHODS

From July 1993 to July 1999, 514 tibial bypass grafts were performed, with 80 bypass grafts in 79 patients with PTFE/DVP as the conduit. Patient demographics included 39 men and 40 women (mean age, 67 years); 42 had diabetes mellitus (53%), 16 had renal failure (20%), and 48 had Eagle criteria for increased cardiac risk (60%). Indications for revascularization were rest pain in 39 (49%) and tissue loss in 41 (51%). Lack of adequate vein resulted from previous failed lower extremity bypass graft (47 [59%]), previous coronary bypass graft (21 [26%]), unsuitable vein (8 [10%]), and absent vein due to ligation and stripping (4 [5%]). Follow-up ranged from 1 to 48 months. Results are reported as primary patency or limb salvage +/- SE.

RESULTS

Bypass grafts originated from the common femoral artery (40 [50%]), the superficial femoral artery (6 [8%]), and the external iliac artery (34 [43%]). Recipient arteries included anterior tibial (17 [21%]), posterior tibial (28 [35%]), and peroneal (35 [44%]). Four-year primary patency and limb salvage rates were 62.89% +/- 10.6% and 79.21% +/- 8.45%, respectively. There was a 24% mortality rate during the follow-up period. Acute failure occurred in 7 grafts with 5 immediate amputations and 2 revisions. A total of 17 grafts failed during the follow-up period, leading to 11 amputations.

CONCLUSION

The DVP technique allows PTFE bypass grafts to tibial arteries with acceptable long-term patency and limb salvage.

Vein interposition cuffs decrease the intimal hyperplastic response of polytetrafluoroethylene bypass grafts

PURPOSE

The modification of the distal anastomosis of polytetrafluoroethylene (PTFE) bypass grafts with vein interposition cuffs (VCs) has been reported to increase graft patency. However, the mechanisms that are responsible for this improved patency are unclear. Because intimal hyperplasia (IH) is a primary cause of prosthetic graft failure, we hypothesized that VCs affect the distal anastomosis by decreasing the IH response of the outflow artery.

METHODS

Twenty-three female domestic Yorkshire pigs (mean weight, 35 kg) underwent 42 femoral PTFE bypass grafting procedures. The PTFE bypass grafts were separated into the following three groups according to distal anastomotic configuration: end-to-side anastomoses (ES), VCs, and cuffs constructed with PTFE (PCs). Four femoral arteries from two pigs served as healthy controls. At sacrifice, the grafts were perfusion fixed, and the distal anastomoses harvested at 1 and 4 weeks. The specimens were hemisected and serially sectioned to identify the heel, toe, and mid-anastomotic regions. The sections were cut into 5-microm segments and analyzed for intima and media thickness and area, intima/media area ratio, and the distribution of IH in the vein cuff. The roles of transforming growth factor-beta1 and platelet-derived growth factor-BB in IH development were assessed with immunohistochemistry.

RESULTS

IH development was significantly lower at all areas of the anastomosis, with VCs compared with ES and PCs at 4 weeks (P </=.001). IH decreased in VCs from 1 to 4 weeks in all areas of the anastomosis (P </=.001). PCs showed pronounced IH at the mid-anastomosis as compared with VCs and ES (P </=.001). IH was most pronounced at the toe with ES and PCs (P </=.001). Qualitatively, VCs altered the site of IH development, sparing the recipient artery with preferential thickening of the vein cuff and formation of a pseudointima at the vein-PTFE interface. Immunohistochemistry results showed positive staining for transforming growth factor-beta1, platelet-derived growth factor-BB, and smooth muscle alpha-actin in the hyperplastic intima.

CONCLUSION

PTFE bypass grafts with VCs had less IH develop than did grafts with ES and PC anastomoses. IH regression in VCs at 4 weeks suggests compensatory vessel wall remodeling mediated by the presence of the VC. Furthermore, VCs caused a redistribution of hyperplasia to the vein-PTFE interface, delaying IH-induced outflow obstruction in the recipient artery. The marked increase in IH with PCs, despite a similar geometric configuration to VCs, suggests that the biologic properties of autogenous tissue dissipate IH development. Similarly, the flow patterns in PCs and VCs should be identical, which suggests a less important role of hemodynamic forces in VC-mediated protection.