The Usefulness of Biosynthetic Vascular Graft Omniflow II and Autologous Veins for the Treatment of Massive Infection of Dacron Vascular Graft with Enterococcus faecalis HLAR

A systematic review and meta-analysis of the use of the Omniflow II biosynthetic graft for aortic reconstruction

OBJECTIVE

Despite the improvements in xenogeneic grafts and surgical techniques, management of aortic graft infection has remained challenging. The optimal graft material has remained controversial, with high rates of reinfection using prosthetic grafts and a limited time for venous harvest in an emergent setting. Recent studies have highlighted an increase in the use of Omniflow II biosynthetic vascular grafts (LeMaitre Vascular, Burlington, MA) for aortic reconstruction. The primary aim of the present study was to review the key outcomes for the Omniflow II graft in terms of reinfection and complications.

METHODS

The National Healthcare Service healthcare databases advanced search function was used to search nine databases for the search term "Omniflow." The present study complied with the PRISMA (preferred reporting items for systematic review and meta-analysis) statement. Eligible studies related to aortic graft infection or in situ aortic reconstruction were selected in accordance with prespecified eligibility criteria and included for review. Data on the surgical technique, comorbidities, graft reinfection, mortality, and complications were combined. The data were analyzed using Stata/MP, version 17 (StataCorp, College Station, TX), and the probabilities were pooled using a DerSimonian and Laird random effects model with Freeman-Tukey arcsine transformation.

RESULTS

Six studies with 60 patients (44 men; age range, 29-89 years) were included. Of the 60 patients, 25 had undergone surgical reconstruction because of early graft infection (<4 months after the index procedure), 24 for late graft infection, and 3 because of mycotic aneurysms. Eight high-risk patients had undergone surgical reconstruction for prevention of an initial graft infection. Staphylococcus aureus, Escherichia coli, and S. epidermis were the most common organisms. Early mortality was 8.83% (95% confidence interval [CI], 1.12%-20.53%), and late mortality was 18.49% (95% CI, 5.51%-35.34%). Follow-up varied from 9 months to 2 years. No graft rupture or graft degeneration had occurred during follow-up. However, 6.2% (95% CI, 0.39%-15.81%) had experienced early graft occlusion, and 3.83% (95% CI, 0.00%-16.34%) had developed early graft stenosis. Two cases of postoperative reinfection were reported. The freedom from reinfection was 97.71% (95% CI, 87.94%-100.00%).

CONCLUSIONS

Use of the Omniflow II graft for aortic reconstruction is a feasible alternative with acceptable mortality and low reinfection rates. However, there is a risk of limb occlusion. Although these studies were of low quality, the Omniflow II graft shows promise in this difficult patient cohort, especially when bifurcated reconstruction is required.

Early Graft, Limb and Mortality Outcomes from the Omniflow II Bio-Synthetic Graft

BACKGROUND

Omniflow II biosynthetic grafts are a commonly used alternative to autologous grafts in vascular bypass procedures. They are chosen for their purported resilience to infection, often in instances of existing graft failure or infection. We examined the short term, 1-3 year outcomes of Omniflow grafts in terms of patency, limb survival and mortality in a sample of 24 individuals.

METHODS

This is a single centred retrospective study of Omniflow II grafts implanted between September 23, 2015 and April 05, 2018 in our department. It includes grafts in all anatomical locations. Primary outcome measures were overall patient survival and time to this, primary graft patency (patency with no intervention) and then limb survival at 1 and 3 years. Kaplan-Meier survival analysis was plotted for the 3 primary outcome measures.

RESULTS

A total of 24 grafts from 24 individuals were included with mean age 71.4 ± 11.7. We included 5 female and 19 male patients. The commonest indication was rest pain/claudication (N = 8) followed by graft occlusion (N = 6). Femoro-popliteal bypass (N = 13) and Femoro-distal bypass (N = 5) were the commonest procedures. Kaplan-Meier survival analysis demonstrated that 1 and 3-year primary patency rates were 54.2% and 37.5% respectively with Limb survival probability of 75% at 1 year and 70.8% at 3 years. These rates were all considerably lower than those found in previous comparative studies. Mortality however, compared favourably with 1 and 3-year survival probability 91.7% and 87.5% on average 296 days (range 95-451 days) after graft implantation.

CONCLUSIONS

We found that rates of primary patency and limb salvage for this graft type were markedly lower than in comparable studies. Further work in the form of a RCT is indicated.

Xenogeneic materials for the surgical treatment of aortic infections

Background

The surgical treatment of aortic infections (AIs) is challenging. In situ aortic reconstructions represent nowadays the favored therapy for fit patients and xenogeneic materials are used increasingly. The aim of this study was to present our experience with xenogeneic reconstructions for AI using self-made bovine pericardium tubes and/or the biosynthetic Omniflow^® II graft.

Methods

This retrospective single-center study included all patients undergoing xenogeneic aortic and aortoiliac reconstructions from December 2015 to June 2020. Patient comorbidities, symptoms, procedural characteristics, types of pathogens and postoperative outcomes were analyzed.

Results

Twenty-eight patients [23 male (82%), median age 68 (range, 28–84) years] were included. Ten patients (36%) had native AIs and 18 (64%) had graft infections, including 3 (11%) aortoesophageal and 2 (7%) aortoduodenal fistulas (ADF). Twenty-four patients (86%) were symptomatic, the most common symptoms being contained aortic rupture (n=8) and sepsis (n=4). The surgical procedures were infra- and juxtarenal aortic repairs (n=11, 39% and n=7, 25%), thoracoabdominal aortic repairs (type IV: n=1, 4%; type V: n=3, 11%), descending thoracic aortic repairs (n=4, 14%) and 2 reconstructions (7%) involving the ascending aorta/aortic arch. Most were urgent (n=10, 43%) or emergent operations (n=11, 35%). Identification of pathogen(s), mostly Gram-positive bacteria, was possible in 25 patients (89%). Twelve patients (43%) had polymicrobial infections and 6 (21%) infections with multi-resistant bacteria. In-hospital mortality was 32% (n=9) due to acute cardiac failure (1/9), endocarditis (1/9), bleeding (3/9) and sepsis (4/9). The most frequent complications were transient need for dialysis (n=12, 43%) and persisting sepsis (n=11, 39%). Two early occlusions of Omniflow^® II grafts were observed (7%). Median follow-up (FU), during which 2 patients died of non-aortic causes, was 14 months (95% CI: 9–19 months). Freedom from reoperation was 100%, there was no evidence for reinfection during FU.

Conclusions

Xenogeneic orthotopic reconstructions for AI can be performed at all aortic levels. Combining bovine pericardium and the Omniflow^® II graft can be useful for reconstructing the branched aortic segments and both materials show appropriate early to midterm outcomes. Nonetheless, AIs are serious conditions associated with relevant morbidity/mortality rates, even in a specialized center.

Aortic treatment of native infection by reconstruction with the Omniflow II biologic prosthesis

Aortic infection is a challenging condition. Fortunately, surgical revision of infected aorta with in situ reconstruction can provide long-term cure. The material for aortic repair remains an area of debate. The Omniflow II (LeMaitre Vascular, Burlington, Mass) prosthesis is a biosynthetic graft made to resist long-term degeneration and allows growth of host tissue with reduction of the risk of arterial infection. It has already been used for peripheral bypass with very low infection rates. Herein, we describe an original case of first-line native aorta replacement by a straight Omniflow II biologic prosthesis for infected aortic aneurysm.