Venous Conduits Have Superior Patency Compared with Prosthetic Grafts for Femorofemoral Bypass

Evaluation of vascular repair by tissue-engineered human acellular vessels or expanded polytetrafluoroethylene grafts in a porcine model of limb ischemia and reperfusion

BACKGROUND

This study evaluated performance of a tissue-engineered human acellular vessel (HAV) in a porcine model of acute vascular injury and ischemia. The HAV is an engineered blood vessel consisted of human vascular extracellular matrix proteins. Limb reperfusion and vascular outcomes of the HAV were compared with those from synthetic expanded polytetrafluoroethylene (ePTFE) grafts.

METHODS

Thirty-six pigs were randomly assigned to four treatment groups, receiving either the HAV or a PTFE graft following a hind limb ischemia period of either 0 or 6 hours. All grafts were 3-cm-long interposition 6-mm diameter grafts implanted within the right iliac artery. Animals were not immunosuppressed and followed for up to 28 days after surgery. Assessments performed preoperatively and postoperatively included evaluation of graft patency, hind limb function, and biochemical markers of tissue ischemia or reperfusion injury. Histological analysis was performed on explants to assess host cell responses.

RESULTS

Postoperative gait assessment and biochemical analysis confirmed that ischemia and reperfusion injury were caused by 6-hour ischemia, regardless of vascular graft type. Hind limb function and tissue damage biomarkers improved in all groups postoperatively. Final patency rates at postoperative day 28 were higher for HAV than for ePTFE graft in both the 0-hour (HAV, 85.7%; ePTFE, 66.7%) and 6-hour (HAV, 100%; ePTFE, 75%) ischemia groups, but these differences were not statistically significant. Histological analyses identified some intimal hyperplasia and host reactivity to the xenogeneic HAV and also to the synthetic ePTFE graft. Positive host integration and vascular cell infiltration were identified in HAV but not ePTFE explants.

CONCLUSION

Based on the functional performance and the histologic profile of explanted HAVs, this study supports further investigation to evaluate long-term performance of the HAV when used to repair traumatic vascular injuries.

Early Outcomes of Complex Vascular Reconstructions in Lower Extremities Using Spiral and Panel Vein Grafts

BACKGROUND

Spiral saphenous vein grafts (SSVG) or paneled vein grafts (PVG) can be used when the diameter of the autologous great saphenous vein does not match the vessel that needs to be repaired. This study aimed to present early results of complex vascular reconstruction with SSVGs and PVGs in the lower extremities.

METHODS

From May 2019 through January 2021, 6 SSVGs and 3 PVGs were used for vascular reconstruction in 9 patients. Patient data were collected retrospectively, including age, gender, cause of vascular pathology, target vessels, concomitant injury, surgical method, additional surgical methods, and hemodynamic status. The Kaplan-Meier method was used to calculate the rate of freedom from reintervention.

RESULTS

Among these patients, 7 had trauma, 1 had graft infection, and 1 had vascular reconstruction after tumor excision. The mean duration of follow-up was 6 ± 6.6 months (range 1-19 months). The rate of freedom from reintervention for any reason was 77.8% at 1 year. Two patients underwent amputation after vascular reconstruction with patent vascular reconstructions. One of the 2 amputations was performed because of infection, and the other was due to ischemia >24 hr. The success rate of reconstruction was 100%, and the primary patency rate was 100%. The rate of limb salvage was 77.8%. There was no death, bleeding, embolism, skin ulcers, graft-related complication, or aneurysmal dilation during follow-up.

CONCLUSIONS

SSVG and PVG were associated with low infection rates and satisfactory short-term patency rates. Both 2 grafts may be good choices when there is a diameter mismatch in vascular reconstructions.

Contemporary Use of the Femoropopliteal Vein in Vascular Reconstructions

INTRODUCTION

Current practice patterns favor endovascular treatment, resulting in fewer open procedures. When needed, greater saphenous vein and/or prosthetic conduits are considered the first choice for open vascular bypass. However, there is a cohort of patients in which these conduits are either not available or not suitable to address the surgical requirements. One alternative is to use femoropopliteal vein (FPV), an often-overlooked conduit. We report on the contemporary use of FPV in a tertiary vascular institution.

METHODS

All patients who underwent FPV harvest, as defined by CPT code 35572, between 2005 and 2019 were identified. Patient demographics (sex, age, baseline laboratory values, medical co-morbidities), indication for use of FPV, complications specific to vein harvest, operative details, post-operative course, and outcomes were recorded.

RESULTS

Ninety patients had harvest of FPV for creation of 123 conduits. In this study, a conduit was defined as a segment of vein used to perfuse a distinctly separate vascular bed. We identified four cohorts in which FPV was used: aorto-iliac reconstruction in 38 patients for infected graft (19), occlusive disease (8), aortitis (5), mycotic aneurysm (5), and malignancy (1); peripheral artery revascularization in 26 patients for ilio-femoral reconstruction (15), femoropopliteal reconstruction (4), upper extremity/cerebrovascular reconstruction (6), and coronary bypass (1); mesenteric revascularization in 20 patients for acute or acute on chronic ischemia (12), chronic ischemia (7) or aneurysm (1); and dialysis access in 6 patients. There was a high incidence of pre-existing comorbid conditions in all groups, but most notably those patients who underwent aorto-iliac reconstruction. Harvest-related or conduit-related complications included compartment syndrome, graft-associated hemorrhage, surgical site infection, and lymphatic complications. Primary graft patency at 3 years was 83% ± 4% (aorto-iliac), 83% ± 6% (peripheral), 100% (mesenteric), and 23% ± 19% (dialysis access, P < 0.001).

CONCLUSIONS

While use of FPV has potential significant harvest-related, conduit-related, or systemic complications, FPV is useful for a variety of needs, almost universally available, and durable. In the current era where endovascular approach is the focus, FPV should not be forgotten as a potential conduit that can be used for a variety of vascular reconstruction indications.

Can concomitant above-knee femoropopliteal bypass with artificial graft affect the outcome of femorofemoral bypass with artificial graft?

OBJECTIVES

Few have studied the effect of concomitant femoropopliteal (FEM-POP) bypass surgery on the outcome of femorofemoral (FEM-FEM) bypass in patients with peripheral arterial disease (PAD). This study was aimed to analyze the risk relationship of concomitant FEM-POP bypass on the patency of FEM-FEM bypass.

METHODS

From March 2009 to April 2020, a total of 27 patients who underwent FEM-FEM bypass surgery using polytetrafluoroethylene grafts were retrospectively analyzed according to concomitant FEM-POP bypass surgery. The mean follow-up duration was 38.20 ± 34.56 months.

RESULTS

The overall primary patency of the FEM-FEM bypass grafts in all 27 patients was 83.7, 78.5, and 72.0 at one, two, and 3 years, respectively. The overall limb salvage rate was 100, 94.1, and 86.9 at one, two, 3 years, respectively. Among them, ten patients underwent FEM-FEM bypass only (group 1). The other 17 patients needed a concomitant FEM-POP bypass and these patients were classified into three groups (group 2, ipsilateral FEM-POP, n = 5; group 3, crossover FEM-POP, n = 6; and group 4, bilateral FEM-POP, n = 6) The comparison of the primary patency of group 1 with the concomitant FEM-POP groups (sum of groups 2, 3, and 4, that is, group 5, n = 17) revealed a statistically significant improved patency for FEM-FEM bypasses not requiring concomitant infra-inguinal bypass (p = .036). Among the concomitant FEM-POP groups, group 2 had the lowest primary patency of the FEM-FEM bypass significantly (p = 0.07). The limb salvage rate of group 4 was significantly low.

CONCLUSIONS

A concomitant FEM-POP bypass influenced the outcome of FEM-FEM bypass surgery. In conclusion, compromised infra-inguinal runoff at either extremity requiring concomitant FEM-POP bypass significantly worsens long-term FEM-FEM bypass patency. In addition, a concomitant bilateral FEM-POP bypass is a risk factor affecting the limb salvage rate in FEM-FEM bypass.

Factors associated with long-term graft patency after lower extremity arterial bypasses

Purpose

This study was conducted to determine factors associated with long-term graft patency after lower extremity arterial bypass (LEAB).

Methods

Database of LEABs for patients with chronic arterial occlusive disease (CAOD) at a single institution was retrospectively reviewed. To determine the factors we compared demographic, clinical, and procedural variables between 2 patient groups; group I (graft patency < 2 years) and group II (graft patency ≥ 5 years after LEAB) using univariable and multivariable analyses.

Results

Among 957 LEABs, 259 limbs (group I, 125 limbs and group II, 134 limbs) in 213 patients were included for the analysis. On a univariable analysis, younger age (69 years vs. 66 years, P = 0.024), hypertension (60.8% vs. 74.6%, P = 0.017), claudication (51.2% vs. 70.9%, P = 0.001), absence of prior intervention (50.4% vs. 73.9%, P < 0.001), common femoral artery based bypass (57.6% vs. 70.1%, P = 0.035), above-the knee bypass (36.8% vs. 64.2%, P < 0.001), postoperative graft salvage procedure (3.2% vs. 14.8%, P = 0.001), and statin use (75.2% vs. 88.8, P = 0.004) were associated with long-term patency. On a multivariate analysis hypertension (odds ratio [OR], 1.91; P = 0.038), claudication (OR, 2.08; P = 0.032), no prior intervention (OR, 2.48; P = 0.001), vein graft (OR, 4.36; P = 0.001), above-the knee bypass (OR, 4.68; P < 0.001), and graft salvage procedures (OR, 7.70; P < 0.001) were identified as independent factors.

Conclusion

These factors can be considered in decision making before treatment of patients with CAOD.

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.

Biomimetic modification of poly(vinyl alcohol): Encouraging endothelialization and preventing thrombosis with antiplatelet monotherapy

Poly(vinyl alcohol) (PVA) has shown promise as a biomaterial for cardiovascular application. However, its antifouling properties prevent in vivo endothelialization. This work examined the endothelialization and thrombogenicity of modified PVA with different concentrations of proteins and adhesion peptides: collagen, laminin, fibronectin, GFPGER, YIGSR, and cRGD. Material surface properties were quantified, and the endothelialization potential was determined with human endothelial colony forming cells. Additionally, platelet attachment was assessed in vitro with human platelet rich plasma, and promising samples were tested in an ex vivo shunt model. This well-established arteriovenous shunt model was used with and without clinically-relevant antiplatelet therapies, specifically acetylsalicylic acid (ASA) with and without clopidogrel to examine the minimum necessary treatment to prevent thrombosis. Collagen, laminin, and GFPGER biomolecules increased endothelialization, with GFPGER showing the greatest effect at the lowest concentrations. GFPGER-PVA tubes tested under whole blood did exhibit an increase in platelet (but not fibrin) attachment compared to plain PVA and clinical controls. However, application of ASA monotherapy reduced the thrombogenicity of GFPGER-PVA below the clinical control with the ASA. This work is significant in developing cardiovascular biomaterials-increasing endothelialization potential while reducing bleeding side effects by using an antiplatelet monotherapy, typical of clinical patients. STATEMENT OF SIGNIFICANCE: We modified the endothelialization potential of synthetic, hydrogel vascular grafts with proteins and peptides of the vascular tissue matrix. Cell attachment was dramatically increased with the GFPGER peptide, and while some additional platelet attachment was seen under flow with whole blood, this was completely knocked down using clinical antiplatelet monotherapy. This indicates that long-term patency of this biomaterial could be improved without the associated bleeding risk of multiple platelet therapies.