A 10-Year Experience with Complementary Distal Arteriovenous Fistula and Deep Vein Interposition for Infrapopliteal Prosthetic Bypasses

Polyester vascular patches acquire arterial or venous identity depending on their environment

Polyester is commonly used in vascular surgery for patch angioplasty and grafts. We hypothesized that polyester patches heal by infiltration of arterial or venous progenitor cells depending on the site of implantation. Polyester patches were implanted into the Wistar rat aorta or inferior vena cava and explanted on day 7 or 30. Neointima that formed on polyester patches was thicker in the venous environment compared to the amount that formed on patches in the arterial environment. Venous patches had more cell proliferation and greater numbers of VCAM-positive and CD68-positive cells, whereas arterial patches had greater numbers of vimentin-positive and alpha-actin-positive cells. Although there were similar numbers of endothelial progenitor cells in the neointimal endothelium, cells in the arterial patch were Ephrin-B2- and notch-4-positive while those in the venous patch were Eph-B4- and COUP-TFII-positive. Venous patches treated with an arteriovenous fistula had decreased neointimal thickness; neointimal endothelial cells expressed Ephrin-B2 and notch-4 in addition to Eph-B4 and COUP-TFII. Polyester patches in the venous environment acquire venous identity, whereas patches in the arterial environment acquire arterial identity; patches in the fistula environment acquire dual arterial-venous identity. These data suggest that synthetic patches heal by acquisition of identity of their environment. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3422-3431, 2017.

Compositions Including Synthetic and Natural Blends for Integration and Structural Integrity: Engineered for Different Vascular Graft Applications

Tissue engineering approaches for small-diameter arteries require a scaffold that simultaneously maintains patency by preventing thrombosis and intimal hyperplasia, maintains its structural integrity after grafting, and allows integration. While synthetic and extracellular matrix-derived materials can provide some of these properties individually, developing a scaffold that provides the balanced properties needed for vascular graft survival in the clinic has been particularly challenging. After 30 years of research, there are now several scaffolds currently in clinical trials. However, these products are either being investigated for large-diameter applications or they require pre-seeding of endothelial cells. This progress report identifies important challenges unique to engineering vascular grafts for high pressure arteries less than 4 mm in diameter (e.g., coronary artery), and discusses limitations with the current usage of the term "small-diameter." Next, the composition and processing techniques used for generating tissue engineered vascular grafts (TEVGs) are discussed, with a focus on the benefits of blended materials. Other scaffolds for non-tissue engineering approaches and stents are also briefly mentioned for comparison. Overall, this progress report discusses the importance of defining the most critical challenges for small diameter TEVGs, developing new scaffolds to provide these properties, and determining acceptable benchmarks for scaffold responses in the body.

The Use of Arteriovenous Fistulae as an Adjunct to Peripheral Arterial Bypass: A Systematic Review and Meta-analysis

BACKGROUND

Peripheral arterial bypass is an effective procedure for the management of patients with critical limb ischaemia. However, it is commonly associated with high rates of graft occlusion and subsequent limb loss. This is particularly apparent when the distal anastomosis is to the below-knee arterial segment. A number of studies have suggested that an arteriovenous fistula (AVF) sited at the distal anastomosis may reduce afterload, improve graft patency, and boost subsequent limb salvage. The aim of this study was to assess the effects of adjuvant AVF on the outcomes of peripheral arterial bypass.

METHODS

The following databases were searched up to May 2015: Medline through Pubmed; the Cochrane Library; EMBASE; and reference lists of articles.

STUDY ELIGIBILITY

All randomised controlled and observational studies that assessed the role of AVF as an adjunct to peripheral arterial bypass were included. Studies were required to include at least one pre-defined outcome. Data were extracted and assessed by two reviewers with any disagreements adjudicated on by the senior author. Pooled risk ratios were calculated using a random effects model. Additional subgroup analyses were performed.

RESULTS

Two randomised controlled trials and seven retrospective cohort studies comprising 966 participants were included. Pooled standardized data showed no difference in primary graft patency (pooled RR = 1.25, 95% CI 0.73-2.16), secondary patency (pooled RR = 1.16, 95% CI 0.82-1.66), or limb salvage at 12-months (pooled RR = 1.13, 95% CI 0.80-1.60) for the peripheral bypass with AVF group compared with peripheral bypass alone. Subgroup analysis indicated a reduction in reintervention rates associated with AVF when performed in conjunction with a synthetic graft (pooled RR = 0.55, 95% CI 0.30-0.98).

CONCLUSION

Although adjuvant AVF is not associated with additional operative complication there is little evidence to support its use. The evidence assessing its merits is weakened by small, retrospective studies with heterogeneous cohorts.

Update on the role of the distal arteriovenous fistula as an adjunct for improving graft patency and limb salvage rates after crural revascularization

BACKGROUND

Critical ischemia of the lower limb continues to challenge the ingenuity of all interventionalists in achieving reliable, predictable, and durable patency. The objective of this study was to investigate the role of the distal arteriovenous fistula (dAVF) to enhance crural revascularization patency rates particularly when prosthetics are used.

METHODS

All patients who underwent crural bypass with dAVF since 1979 were included. Graft patency was assessed periodically by clinical examination and Doppler studies. Results were analyzed by life-table methodology to obtain primary and secondary patency rates and limb salvage rates.

RESULTS

A total of 502 crural bypass plus dAVF procedures were studied within 4 consecutive periods. Primary patency rates at 1 and 3 years for each of the 4 consecutive periods were (1) 36% and 10%, (2) 52% and 15%, (3) 54% and 31%, and (4) 70% and 46%. Corresponding secondary patency rates were (1) 43% and 17%, (2) 60% and 29%, (3) 60% and 44%, and (4) 72% and 50%. There was a statistically significant improvement for primary and secondary patency rates when comparing the last 2 periods with the first 2. Limb salvage rates also showed significant improvement for the same periods.

CONCLUSIONS

Creation of a dAVF should be considered as a component of crural revascularization when prosthetics are used. The altered hemodynamics associated with dAVF prevents overload and as a consequence, potential bypass closure. The contribution of dAVF for enhancing patency rates when autologous vein is used with compromised runoff requires further study.

Basic data related to surgical infrainguinal revascularization procedures: a twenty year update

In 1990, Dalman and Taylor published a compilation of reported data that were identified by them as related to infrainguinal revascularization procedures in peripheral vascular surgery during the decade of the 1980s. The intervening 20 years has seen revolutionary advances in the field of peripheral vascular surgery, especially in the adoption of endovascular techniques, and an explosion of data related to emerging technologies in the field of infrainguinal revascularization. The tables in this manuscript reflect the evolution of our surgical knowledge during the turn of the 21st century. The superior patency of autologous saphenous vein in all positions is reaffirmed.