Analysis of Failure-mechanisms of Cryopreserved Vascular Allografts in Peripheral Reconstructions

Abstract

Introduction: Cryopreserved vascular allografts represent a well known option in the treatment of vascular infections. Moreover several groups also suggested their use in case of patients with no suitable veins requiring an infragenicular bypass. The aim of the present study was to evaluate the failure mechanisms of cryopreserved allografts in peripheral reconstructions in a cohort of patients treated at a single Institution. Methods: We retrospectivly analized a prospectively collected database comprising all patients undergoing a peripheral reconstruction with cryopreserved arterial or venous allografts between August 2010 and January 2019. The composite result of graft failure (occlusion + degeneration + any graft-related complication) was calculated as a primary endpoint. In case of reintervention hystological analysis of a segment of allograft was performed. Results: A total of 20 patients [mean age 66.1 +/- 10.3 yy, M 66% (12/18)] underwent 25 vascular in-situ reconstruction with cryopreserved arterial or venous allografts. Indication for treatment was infection of a previous prosthetic graft in 12 cases, critical limb ischemia in 8, allograft degeneration in 3 and mycotic pseudoaneurym in 2. Type of reconstruction are reassumed in table I Table I. Type o.... In 17 cases an arterial allograft was used (11 single segment, 6 multiple segments) and in 8 cases a vein allograft (6 single segment, 2 multiple segments). At 30 days there were 3 deaths (1 myocardial infarction, 1 rupture of thoracic aortic aneurysm, 1 anastomotyc disrupture) with 2 additional deaths during follow up (1 drug overdose, 1 intestinal ischemia). Mean follow-up was 31 months (min 1 - max 81) with no patients lost to follow up. Overall graft failure occurred in 7 cases (28%) (3 aneurysmal degenerations, 2 occlusions, 2 anastomotyc disrupture) with reintervention with allograft performed in 4 cases. There was no statistical difference in the incidence of the composite endpoint between venous and arterial grafts [OR 0.71 (0.098 - 5.2), p 1], between patients with infection and without infection [OR 1.8 (0.26 - 12), p 0.66] and between single and multiple segments grafts [OR 2.8 (0.42 - 2.9), p 0.34], although occlusions occurred only in veins (2/8, 25%) and aneurismal degeneration only in arterial allografts (3/17, 17%). Hystological analysis was available for 5 allografts: 2 anastomotyc disruptures showing wall necrosis due to infection, 3 aneurysmal degenerations showing a chronic flogistic pattern suggestive of immune-mediated rejection. Kaplan-Meier estimates showed an overal 26% of freedom from graft failure at 60 months, with no difference between patients with and without infection and venous and arterial allografts (Logrank test p: 019 and 0.26 respectively). Conclusion: In our series the failure rate of allografts was not low, although their use was limited to very high risk situations. Accurate follow up is mandatory as the risk of aneurysmal degeneration is not negligible with arterial allografts, although they seem to offer a better patency rate compared to veins. Immune-mediated rejection plays a role in aneurysmal degeneration while uncontrollable infection greatly hinders the early postoperative outcome.Table IType of peripheral reconstruction with allografts and type of allografts usedType of ReconstructionN (%)Type of allografts (N)Composite axillo-femoral bypass1 (4%)Single Arterial (1)Femoral tibial bypass4 (16%)Multiple Arterial (2) Single Venous (1) Multiple Venous (1)Femoral femoral crossover bypass2 (8%)Single Arterial (2)Below knee femoral popliteal bypass5 (20%)Single Arterial (1) Multiple Arterial (3) Single Venous (1)Above knee femoral popliteal bypass2 (8%)Single Arterial (1) Single Venous (1)Iliac femoral bypass3 (12%)Single Arterial (2) Multiple Arterial (1)Femoral truncal bypass2 (8%)Single Venous (1) Multiple Venous (1)Common femoral reconstruction4 (16%)Single Arterial (3) Single Venous (1)Bypass of a dilated segment of a previous allograft2 (8%)Single Arterial (2) Open table in a new tab Disclosure: Nothing to disclose