A Unique Case of an Expanded Polytetrafluoroethylene Graft Rupture 14 Years after Abdominal Aortic Aneurysm Open Repair Managed with Placement of a Thoracic Endograft

We report a unique case of expanded polytetrafluoroethylene (ePTFE) tube graft rupture that occurred 14 years after abdominal aortic aneurysm (AAA) repair. Endovascular repair with a thoracic endograft was performed. Postoperatively, an increase in the size of the existing hematoma with active extravasation occurred and was managed with iliolumbar artery embolization. Τo the best of our knowledge, rupture of ePTFE graft used for AAA repair has not been reported in the literature.

Silk fibroin vascular graft: a promising tissue-engineered scaffold material for abdominal venous system replacement

No alternative tissue-engineered vascular grafts for the abdominal venous system are reported. The present study focused on the development of new tissue-engineered vascular graft using a silk-based scaffold material for abdominal venous system replacement. A rat vein, the inferior vena cava, was replaced by a silk fibroin (SF, a biocompatible natural insoluble protein present in silk thread), tissue-engineered vascular graft (10 mm long, 3 mm diameter, n = 19, SF group). The 1 and 4 -week patency rates and histologic reactions were compared with those of expanded polytetrafluoroethylene vascular grafts (n = 10, ePTFE group). The patency rate at 1 and 4 weeks after replacement in the SF group was 100.0% and 94.7%, and that in the ePTFE group was 100.0% and 80.0%, respectively. There was no significant difference between groups (p = 0.36). Unlike the ePTFE graft, CD31-positive endothelial cells covered the whole luminal surface of the SF vascular graft at 4 weeks, indicating better endothelialization. SF vascular grafts may be a promising tissue-engineered scaffold material for abdominal venous system replacement.

Femoral Pseudoaneurysm in IV Drug Abusers: Single-center Study Experience

Background: Pseudoaneurysm of the femoral artery is the most common complication among IV drug abusers who inject drugs in groin. These are usually infective and potentially fatal so it requires astute clinical recognition and prompt treatment, possessing a significant challenge to vascular surgeons. Methods: We present a retrospective descriptive study and the prevalent practice of their management covering the period from 2013 July- December 2019 at our center. Data regarding demography, presentation, surgical management, and the outcome was analyzed. Results: Among 368 femoral pseudoaneurysm operated during the period, groin swelling with pulsatile mass was the most frequent presentation accounting 304 (82.61%) patients. About 67.12% (247 patients) of the pseudoaneurysm has purulent discharge and 60.07% (221 patients) had bleeding at presentation out of which 211patients had hepatitis C (HCV), hepatitis B (HBsAg) and/or Human Immunodeficiency virus (HIV) status positive. Thirty six patients (9.78%) presented with femoral pseudoaneurysm in both groins. Ligation and excision of the pseudoaneurysm were done in all cases while delayed revascularization was done in eight patients with expanded Polytetrafluoroethylene (ePTFE) graft in one patient and venous bypass grafts in other 7 cases. All patients after bypass had no major limb loss and two patients had a patent graft at five years follow up. There were nine mortalities and thirty two patients underwent amputation. Conclusions: Infected femoral pseudoaneurysm can be managed by ligation of the involved artery with delayed revascularization if required without major limb and life loss. Keywords: Delayed revascularization; drug abuser; infected pseudoaneurysm; ligation

Patency of ePTFE Arteriovenous Graft Placements in Hemodialysis Patients: Systematic Literature Review and Meta-Analysis

Arteriovenous grafts (AVGs) are an appropriate option for vascular access in certain hemodialysis patients. Expanded polytetrafluoroethylene (ePTFE) has become the dominant material for such grafts, due in part to innovations in graft design and surgical interventions to reduce complications and improve patency rates. Comprehensive evidence syntheses have not been conducted to update AVG performance in an era in which both access choice and ePTFE graft functioning may have changed. We conducted a systematic review and meta-analysis summarizing outcomes from recent studies of ePTFE AVGs in hemodialysis, following PRISMA standards. Literature searches were conducted in multiple databases to identify observational and interventional studies of AVG patency and infection risk. Primary, primary-assisted, and secondary patency rates were analyzed at 6, 12, 18, and 24 months postplacement. Kaplan–Meier graft survival plots were digitized to recreate individual patient-level data. Patency rates were pooled using a random effects model. We identified 32 studies meeting our selection criteria that were published from 2004 through 2019. A total of 38 study arms of ePTFE grafts were included, representing 3381 AVG accesses placed. The mean primary, primary-assisted, and secondary patency rates at 1 year were 41% (95% CI, 35% to 47%), 46% (95% CI, 41% to 51%), and 70% (95% CI, 64% to 75%), respectively. Mean 24-month patency rates were 28% (95% CI, 22% to 33%), 34% (95% CI, 27% to 41%), and 54% (95% CI, 47% to 61%), respectively. A high degree of heterogeneity across studies was observed. Overall risk of infection was not consistently reported, but among available studies the pooled estimate was 9% per patient-year (95% CI, 6% to 12%). This meta-analysis provides an up-to-date estimate of the performance of ePTFE AVGs, within the context of improved graft designs and improved interventional techniques.

Computational study on the haemodynamic and mechanical performance of electrospun polyurethane dialysis grafts

Compliance mismatch between an arteriovenous dialysis graft (AVG) and the connected vein is believed to result in disturbed haemodynamics around the graft–vein anastomosis and increased mechanical loading of the vein. Both phenomena are associated with neointimal hyperplasia development, which is the main reason for AVG patency loss. In this study, we use a patient-specific fluid structure interaction AVG model to assess whether AVG haemodynamics and mechanical loading can be optimised by using novel electrospun polyurethane (ePU) grafts, since their compliance can be better tuned to match that of the native veins, compared to gold standard, expanded polytetrafluoroethylene (ePTFE) grafts. It was observed that the magnitude of flow disturbances in the vein and the size of anastomotic areas exposed to highly oscillatory shear ($$\hbox {OSI} >0.25$$OSI>0.25) and very high wall shear stress ($$>40 \hbox { Pa}$$>40Pa) were largest for the ePTFE graft. Median strain and von Mises stress in the vein were similar for both graft types, whereas highest stress and strain were observed in the anastomosis of the ePU graft. Since haemodynamics were most favourable for the ePU graft simulation, AVG longevity might be improved by the use of ePU grafts.

Amnion-derived mesenchymal stem cells improve viability of endothelial cells exposed to shear stress in ePTFE grafts

Purpose: Blood vessel reconstruction is an increasing need of patients suffering from cardiovascular diseases. For the development of microvascular prostheses, efficient endothelialization is mandatory to prevent graft occlusion. Here, we assessed the impact of amnion-derived mesenchymal stem/stromal cells (hAMSC), known for their important angiogenic potential, on the integrity and stability of endothelial cells exposed to shear stress in vascular grafts. Methods: Human placental endothelial cells (hPEC) were cultured at the inner surface of an expanded polytetrafluoroethylene (ePTFE) graft positioned within a bioreactor and exposed to a minimal shear stress of 0.015 dyne/cm2 or a physiological shear stress of 0.92 dyne/cm2. hAMSC attached to the outer graft surface were able to interact with human placental endothelial cells by paracrine factors. Results: Microscopical analysis and evaluation of glucose/lactate metabolism evidenced successful cell seeding of the graft: hPEC formed a stable monolayer, hAMSC showed a continuous growth during 72 h incubation. hAMSC improved the viability of hPEC exposed to 0.015 dyne/cm2 as shown by a decreased lactate dehydrogenase release of 13% after 72 h compared to hPEC single culture. The viability-enhancing effect of hAMSC on hPEC was further improved by 13% under physiological shear stress. Angiogenesis array analysis revealed that hPEC exposed to physiological shear stress and hAMSC co-culture reduced the secretion of angiogenin, GRO, MCP-1, and TIMP-2. Conclusion: hAMSC exerted best survival-enhancing effects on hPEC under exposure to physiological shear stress and modulated endothelial function by paracrine factors. Our data support further studies on the development of grafts functionalized with hAMSC–derived secretomes to enable fast clinical application.