Four years' results of a prospective, randomized clinical trial comparing polytetrafluoroethylene and modified human umbilical vein for below-knee femoropopliteal bypass

Lower Extremity Bypass Using Bovine Carotid Artery Graft (Artegraft): An Analysis of 124 Cases with Long-Term Results

INTRODUCTION

Although biological grafts have been utilized as a vascular conduit in leg bypass for many years, reports of a bovine carotid artery graft (BCAG) in lower extremity revascularization have been scarce. This study analyzed the outcome of lower leg bypass using BCAG.

METHODS

A retrospective review of a prospectively collected database of all patients undergoing lower extremity bypass using BCAG from 2002 to 2017 was performed. Clinical outcomes including graft patency and limb salvage were evaluated.

RESULTS

A total of 124 BCAG (Artegraft, North Brunswick, NJ) were implanted in 120 patients for lower extremity revascularization. Surgical indications included disabling claudication in 12%, rest pain in 36%, tissue loss in 48%, and infected prosthetic graft replacement in 3%. Autologous saphenous vein was either inadequate or absent in 72% of patients. BCAG was used in 46 patients (37%) who had a prior failed ipsilateral leg bypass. Distal anastomosis was performed in the above-knee popliteal artery, below-knee popliteal artery, and tibial artery in 30 cases (25%), 32 cases (26%), and 48 cases (39%), respectively. Distal anastomotic patch was created in all tibial artery to allow BCAG-tibial reconstruction. The yearly primary patency rates in 5 years were 86.5, 76.4, 72.2, 68.3, and 67.5%, respectively. The corresponding yearly secondary patency rates were 88.5, 84.7, 82.4, 78.5, and 75.6%, respectively. The limb salvage rate at one year was 83.6% and at five years was 86.2% for patients with critical limb ischemia. Multivariate analysis showed poor runoff score (P = 0.03, 95% CI, 1.3-5.3; OR, 1.6) was independently associated with graft occlusion.

CONCLUSION

BCAG is an excellent vascular conduit and provides good long-term results in lower extremity bypass.

Endovascular rescue of long-term vascular graft implants and need for continuous surveillance

We present two cases of vascular graft degradation after long-term implantation. In both patients, endovascular techniques were employed to effect continued graft patency and function. Furthermore, these cases lend further credence to the doctrine of lifelong surveillance of all vascular interventions regardless of graft material. Postoperative surveillance of vascular interventions is generally recommended to avoid failures by identifying “the failing graft”¹ at the earliest possible time to facilitate corrective procedures. There is a tendency that with continued function, over time, surveillance methods are spread farther apart and in fact often discontinued. Recent experiences with two cases illustrate the vital importance of lifelong continuous surveillance regardless of the site, graft material, or absence of symptoms. Clearly, the patient's compliance is essential. Both patients consented to the publication of their cases.

Graft type for femoro-popliteal bypass surgery

BACKGROUND

Femoro-popliteal bypass is implemented to save limbs that might otherwise require amputation, in patients with ischaemic rest pain or tissue loss; and to improve walking distance in patients with severe life-limiting claudication. Contemporary practice involves grafts using autologous vein, polytetrafluoroethylene (PTFE) or Dacron as a bypass conduit. This is the second update of a Cochrane review first published in 1999 and last updated in 2010.

OBJECTIVES

To assess the effects of bypass graft type in the treatment of stenosis or occlusion of the femoro-popliteal arterial segment, for above- and below-knee femoro-popliteal bypass grafts.

SEARCH METHODS

For this update, the Cochrane Vascular Information Specialist searched the Vascular Specialised Register (13 March 2017) and CENTRAL (2017, Issue 2). Trial registries were also searched.

SELECTION CRITERIA

We included randomised trials comparing at least two different types of femoro-popliteal grafts for arterial reconstruction in patients with femoro-popliteal ischaemia. Randomised controlled trials comparing bypass grafting to angioplasty or to other interventions were not included.

DATA COLLECTION AND ANALYSIS

Both review authors (GKA and CPT) independently screened studies, extracted data, assessed trials for risk of bias and graded the quality of the evidence using GRADE criteria.

MAIN RESULTS

We included nineteen randomised controlled trials, with a total of 3123 patients (2547 above-knee, 576 below-knee bypass surgery). In total, nine graft types were compared (autologous vein, polytetrafluoroethylene (PTFE) with and without vein cuff, human umbilical vein (HUV), polyurethane (PUR), Dacron and heparin bonded Dacron (HBD); FUSION BIOLINE and Dacron with external support). Studies differed in which graft types they compared and follow-up ranged from six months to 10 years.Above-knee bypassFor above-knee bypass, there was moderate-quality evidence that autologous vein grafts improve primary patency compared to prosthetic grafts by 60 months (Peto odds ratio (OR) 0.47, 95% confidence interval (CI) 0.28 to 0.80; 3 studies, 269 limbs; P = 0.005). We found low-quality evidence to suggest that this benefit translated to improved secondary patency by 60 months (Peto OR 0.41, 95% CI 0.22 to 0.74; 2 studies, 176 limbs; P = 0.003).We found no clear difference between Dacron and PTFE graft types for primary patency by 60 months (Peto OR 1.67, 95% CI 0.96 to 2.90; 2 studies, 247 limbs; low-quality evidence). We found low-quality evidence that Dacron grafts improved secondary patency over PTFE by 24 months (Peto OR 1.54, 95% CI 1.04 to 2.28; 2 studies, 528 limbs; P = 0.03), an effect which continued to 60 months in the single trial reporting this timepoint (Peto OR 2.43, 95% CI 1.31 to 4.53; 167 limbs; P = 0.005).Externally supported prosthetic grafts had inferior primary patency at 24 months when compared to unsupported prosthetic grafts (Peto OR 2.08, 95% CI 1.29 to 3.35; 2 studies, 270 limbs; P = 0.003). Secondary patency was similarly affected in the single trial reporting this outcome (Peto OR 2.25, 95% CI 1.24 to 4.07; 236 limbs; P = 0.008). No data were available for 60 months follow-up.HUV showed benefits in primary patency over PTFE at 24 months (Peto OR 4.80, 95% CI 1.76 to 13.06; 82 limbs; P = 0.002). This benefit was still seen at 60 months (Peto OR 3.75, 95% CI 1.46 to 9.62; 69 limbs; P = 0.006), but this was only compared in one trial. Results were similar for secondary patency at 24 months (Peto OR 4.01, 95% CI 1.44 to 11.17; 93 limbs) and at 60 months (Peto OR 3.87, 95% CI 1.65 to 9.05; 93 limbs).We found HBD to be superior to PTFE for primary patency at 60 months for above-knee bypass, but these results were based on a single trial (Peto OR 0.38, 95% CI 0.20 to 0.72; 146 limbs; very low-quality evidence). There was no difference in primary patency between HBD and HUV for above-knee bypass in the one small study which reported this outcome.We found only one small trial studying PUR and it showed very poor primary and secondary patency rates which were inferior to Dacron at all time points.Below-knee bypassFor bypass below the knee, we found no graft type to be superior to any other in terms of primary patency, though one trial showed improved secondary patency of HUV over PTFE at all time points to 24 months (Peto OR 3.40, 95% CI 1.45 to 7.97; 88 limbs; P = 0.005).One study compared PTFE alone to PTFE with vein cuff; very low-quality evidence indicates no effect to either primary or secondary patency at 24 months (Peto OR 1.08, 95% CI 0.58 to 2.01; 182 limbs; 2 studies; P = 0.80 and Peto OR 1.22, 95% CI 0.67 to 2.23; 181 limbs; 2 studies; P = 0.51 respectively)Limited data were available for limb survival, and those studies reporting on this outcome showed no clear difference between graft types for this outcome. Antiplatelet and anticoagulant protocols varied extensively between trials, and in some cases within trials.The overall quality of the evidence ranged from very low to moderate. Issues which affected the quality of the evidence included differences in the design of the trials, and differences in the types of grafts they compared. These differences meant we were often only able to combine and analyse small numbers of participants and this resulted in uncertainty over the true effects of the graft type used.

AUTHORS' CONCLUSIONS

There was moderate-quality evidence of improved long-term (60 months) primary patency for autologous vein grafts when compared to prosthetic materials for above-knee bypasses. In the long term (two to five years) there was low-quality evidence that Dacron confers a small secondary patency benefit over PTFE for above-knee bypass. Only very low-quality data exist on below-knee bypasses, so we are uncertain which graft type is best. Further randomised data are needed to ascertain whether this information translates into an improvement in limb survival.

Clinical results of biologic prosthesis: A systematic review and meta-analysis of comparative studies

Background

Biologic prosthesis (BP) has been reported as a safe alternative to polytetrafluoroethylene (PTFE) in vascular reconstruction. However, efficacy of BP remains controversial. We, therefore, conducted a systematic review to summarize previous available evidences comparing the BP and PTFE in terms of clinical outcomes.

Materials and methods

A literature search of the MEDLINE and Scopus was performed to identify comparative studies reporting outcomes of BP, PTFE, and/or autologous veins graft (VG) in vascular access for hemodialysis or femoropopliteal bypass. The outcome of interest was graft patency. Two reviewers independently extracted data. Meta-analysis with a random-effect model was applied to pool a risk ratio (RR) across studies.

Results

Among 584 articles identified, 11 studies (4 randomized controlled trials (RCT) and 7 cohorts) comprising 2627 patients were eligible for pooling. Seven studies compared BP with PTFE and 3 studies compared PTFE with VG. Among BP vs PTFE, pooling based on 3 RCTs yielded the pooled RR of 1.54 (95% CI: 1.10, 2.16), indicating 54% higher graft patency in VG than PTFE. Adding the 7 cohorts in this pooling yield similar results with the pooled RR of 1.29 (95% CI: 1.15, 1.45). The pooled RR of graft patency for BP vs VG was 0.74 (95% CI, 0.55, 1.00), indicating 26% lower graft patency in BP than VG.

Conclusions

Our first meta-analysis indicated that the biosynthetic prosthesis might be benefit over PTFE by increasing graft patency. An updated meta-analysis or a large scale randomized control trial is required to confirm this benefit.

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This study summarized the gap of knowledge of clinical outcome when compare with biologic prosthesis and PTFE.

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This first meta-analysis was shown clearly about results and high performance of study were collected.

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For the conclusion, high efficacy of alternative treatment was shown, however, further study needed to confirm the results.

Optimal management of infrainguinal arterial occlusive disease

Peripheral arterial occlusive disease is becoming a major health problem in Western societies as the population continues to age. In addition to risk of limb loss, the complexity of the disease is magnified by its intimate association with medical comorbidity, especially cardiovascular and cerebrovascular disease. Risk factor modification and antiplatelet therapy are essential to improve long-term survival. Surgical intervention is indicated for intermittent claudication when a patient’s quality of life remains unacceptable after a trial of conservative therapy. Open reconstruction and endovascular revascularization are cornerstone for limb salvage in patients with critical limb ischemia. Recent advances in catheter-based technology have made endovascular intervention the preferred treatment approach for infrainguinal disease in many cases. Nevertheless, lower extremity bypass remains an important treatment strategy, especially for reasonable risk patients with a suitable bypass conduit. In this review, we present a summary of current knowledge about peripheral arterial disease followed by a review of current, evidence-based medical and surgical therapy for infrainguinal arterial occlusive disease.

Proliferation of endothelial cell on polytetrafluoroethylene vascular graft materials carried VEGF gene plasmid

OBJECTIVE

To investigate whether vascular endothelial growth factor (VEGF) gene plasmid carried by polytetrafluoroethylene (PTFE) vascular graft materials could transfect endothelial cells (ECs) and promote their growth.

METHODS

PTFE vascular graft materials carried with pCDI-hVEGF(121), pCDI or pEGFP were incubated in Tris-buffer solution and the values of optical density of 260 nm at different time were plotted, then the DNA controlled release curve was made. ECs derived from human umbilical vein were seeded on the pCDI-hVEGF(121)/pCDI/pEGFP-PTFE materials or tissue culture plates, ECs numbers were counted and VEGF protein concentrations at different time were measured by enzyme-linked immunoadsorbent assay method. Green fluorescent protein (GFP) expression in ECs on pEGFP-PTFE materials was examined with fluorescence microscopy.

RESULTS

The controlled release curve showed that the gene released from PTFE materials was rapid within 8 h, then slowed down and that the gene released continuously even after 72 h. At 24, 72 and 120 h, ECs number and proliferation rate of pCDI-hVEGF(121)-PTFE materials were higher than those of pCDI or pEGFP-PTFE materials (P<0.05). VEGF protein concentration of pCDI-hVEGF(121)-PTFE materials was higher than that of pCDI or pEGFP-PTFE materials at 6, 24, 72 and 120 h (P<0.01). GFP expression in ECs on the pEGFP-PTFE materials could be detected by fluorescence microscopy.

CONCLUSION

PTFE graft can be used as a carrier of VEGF gene plasmid, VEGF gene carried by PTFE can transfect ECs and promote ECs growth.

Pulsed excimer laser versus continuous-wave Nd:YAG laser versus conventional angioplasty of peripheral arterial occlusions: prospective, controlled, randomised trial

Early clinical studies of coronary and peripheral laser angioplasty showed that arterial occlusions could be recanalised by continuous-wave lasers delivered with contact probes and by pulsed lasers applied with multifibre catheters. However, whether laser-assisted angioplasty improves success rates in reopening occlusions and in long-term patency rates is unclear. We have compared the primary recanalisation and long-term patency rates after laser-assisted and conventional percutaneous transluminal angioplasty (PTA) of femoropopliteal artery occlusions in 116 consecutive symptomatic patients (excimer laser 37, Nd:YAG laser 40, PTA 39). Primary recanalisation was achieved in 81 patients (70%). The primary recanalisation rate achieved with the excimer laser was significantly lower than that with the Nd:YAG laser (49% vs 78%, p < 0.01) or with PTA (82%, p < 0.003). The overall angiographic recanalisation rate (primary and secondary recanalisation) after laser and PTA was 89%. After 3 months, clinical improvement was recorded in 76% of patients. Clinical long-term results were available in 94 (91%), and angiographic long-term results in 77 (75%), of 103 successfully recanalised patients. Life-table analysis of the long-term results revealed no significant difference of the restenosis rate between the three treatment groups. The 12-month patency rate was 60% as assessed clinically and 39% as judged by angiography. Primary and secondary recanalisation rates and long-term patency rates were significantly correlated with length of the occlusion. Our results suggest that PTA of femoropopliteal artery occlusions is only indicated if the occlusion is short (< 8 cm) and that laser-assisted angioplasty should only be used after failure of conventional PTA.

In vivo evaluation of four chemically processed biological grafts implanted as infrarenal arterial substitutes in dogs

Four chemically processed grafts implanted as arterial substitutes in dogs were evaluated as blood conduits in terms of patency rates, healing characteristics and biostability. Omniflow, Biopolymeric, Dardik-Biograft of the second generation and BIMA grafts were implanted as infrarenal aortic substitutes for 4, 24 and 48 h (short-term), 1, 2 and 4 wk (medium-term), 3 and 6 month (long-term), each type of graft being implanted for a complete series. The explanted grafts were evaluated macroscopically and processed for light and scanning electron microscopy. One Omniflow graft was occluded at 6 months and two Dardik-Biografts were thrombosed, one at 24 h and one at 1 month. All explanted grafts in the Biopolymeric series and in the BIMA were patent at the animals' death. Histological studies revealed frequent subintimal fibrosis in the Biopolymeric and Omniflow grafts. A peripheral inflammatory reaction was present in most grafts explanted. Scanning electron microscopy showed an aggravation of flow surface irregularities, after implantation of Omniflow, Biopolymeric and Dardik-Biograft, compared to virgin prostheses. These grafts presented an internal capsulae on the graft flow surface along the anastomoses. The capsulae slightly extended towards the centre of the graft after long-term implantation, (6 month) and corresponded to the pannus. Endothelial-like cells covered this pannus. The BIMA graft performed the most satisfactorily and retained its blood compatibility best, that is, the luminal surface was smooth with only minor thrombotic deposits and a thin pannus along the anastomotic lines.