Graft Explantation Research Articles

Abscess Formation Requiring Extraluminal Arterial Graft Explantation and Bypass Surgery.

Abscess Formation Requiring Extraluminal Arterial Graft Explantation and Bypass Surgery.

Outcomes of patients with aortic vascular graft and endograft infections initially contra-indicated for complete graft explantation.

Complete excision in patients with aortic vascular graft and endograft infections (VGEIs) is a significant undertaking, and many patients never undergo definitive treatment. Knowing their fate is important to be able to assess the risks of graft excision vs alternative strategies. This study analyzed their life expectancy and sepsis-free survival. VGEIs were diagnosed according to the Aortic Graft Infection (MAGIC) criteria, and patients turned down for graft removal from November 2006 to December 2020 were included. Primary endpoints were aortic-related and sepsis-free survival estimated using the Kaplan-Meier method. A Cox proportional hazards regression analysis was used to compute the hazard ratio (HR) and 95% confidence interval (CI) as estimates of survival without sepsis. Seventy-four patients were included, with a median age of 71years (range, 63-79years). The index aortic repair was either open (n= 33; 44.6%), endovascular (n= 19; 25.7%), or hybrid (n= 22; 29.7%). Causative organisms were identified in 56 patients (75.7%). At presentation, 26 patients (35.1%) required salvage surgery, open (n= 22; 29.7%) or endovascular (n= 8; 10.8%), and 17 radiological drainage (23.0%). During follow-up, eight required drainage and 11 (14.9%) graft removal (five complete). Infectious complications included pseudoaneurysms (n= 14; 18.9%), rupture (n= 9; 12.2%), gastro-intestinal bleeding (n= 13; 17.6%), septic embolisms (n= 4; 5.4%), and thrombosis (n= 12; 16.2%). In-hospital mortality was 20.3% (n= 15), freedom from aortic-related death and overall survival was 77.1% (95% CI, 65.2%-85.3%) and 70.4% (95% CI, 58.3%-79.7%) at 1year, and 61.7% (95% CI, 46.1%-74.0%) and 43.1% (95% CI, 29.2%-56.3%) at 5years. Sepsis recurrence occurred in 37 patients (50.0%). Seven (16.3%) developed acquired antimicrobial resistance. Malnutrition (HR, 3.3; 95% CI, 1.4-7.6; P= .005), hemorrhagic shock at presentation (HR, 2.9; 95% CI, 1.0-8.2; P= .048), aorto-enteric fistulae (HR, 3.3; 95% CI, 1.3-8.4; P= .011), fungal coinfection (HR, 3.5; 95% CI, 1.2-11.5; P= .030), and infection with resistant micro-organisms (HR, 3.1; 95% CI, 1.1-8.3; P= .023) were significantly associated with worse survival without sepsis. In-hospital and aortic-related mortality were significant, but with salvage surgery and antibiotic therapy, the median survival was 3years. Sepsis recurrence remained frequent, and further procedures were needed. These outcomes should be considered when graft excision is proposed. Known predictors of adverse outcomes should become important points for discussion in multidisciplinary team meetings.

Referral Centre Experience with Infected Abdominal Aortic Endograft Explantation

The increasing use of endovascular aneurysm repair (EVAR) appears to be associated with the burden of vascular endograft infections. Complete stent graft explantation is recommended but leads to significant mortality. This study aimed to assess the technical challenges, complications, and mortality rate following infected endograft explantation. Patients who underwent abdominal aortic endograft explantation for infection at the Bordeaux University Hospital from July 2008 to December 2020 were included retrospectively in this single centre observational study. The diagnosis was established based on the MAGIC criteria. The primary endpoint was 30 day mortality. Secondary endpoints were 90 day and in hospital mortality, survival, and re-infection. Thirty-four patients were included, median age 69 years (interquartile range [IQR] 65, 76), with four (12%) treated as an emergency. The median time from EVAR to explantation was 17.5 months (4.5 - 36.3). In situ reconstruction was carried out with prosthetic grafts in 24 patients (71%, including 23 antimicrobial grafts combining silver and triclosan), and biological grafts in 10 (five femoral veins, four arterial allografts, three bovine patches, one biosynthetic graft). Seventeen aorto-enteric fistulae (AEnF) were addressed with direct repair of the intestinal tract (n= 10/17; 59%) or resection and anastomosis (n= 7/17; 41%). The culture was polymicrobial in 12 patients (35%) and remained sterile in four (12%). The 30 day and in hospital mortality rates were 21% (n= 7) and 27% (n= 9). Twenty-five patients (73%) presented with early post-operative complications, requiring 16 revision procedures (47%). Over a median follow up of 16.2 months (IQR 8.3, 33.6), the mortality rate was 35% (n= 12; 11 aortic related; 32%), with two re-infections (6%), both after biological reconstruction (one for an AEnF). Early morbidity and mortality remain high after complete infected endograft explantation, even in a high volume centre. Comparison with other treatment modalities in large multicentre cohorts might be of interest.

337.10: Monotherapy With TNX-1500, a Fc-Modified Anti-CD154mAb, Prolongs Cardiac Allograft Survival in Cynomolgus Monkeys

Purpose: Blockade of the CD40/CD154 T cell costimulation pathway is a promising approach to replace conventional clinical immunosuppressive therapy. TNX-1500 (TNX)* is a novel humanized anti-CD154 mAb that contains the hu5c8 Fab region and an Fc region engineered to modulate FcγR2 binding to reduce the risk of thromboembolic events seen with hu5c8 IgG1 in previous clinical trials. Its efficacy was evaluated in cynomolgus monkey heterotopic heart allograft recipients. Methods: Cynomolgus monkey heterotopic cardiac allograft recipients were treated with TNX 30mg/kg iv 2x weekly for 2 weeks, then either a ‘standard-dose’ regimen of 20mg/kg weekly from days 21-180 (sTNX, n=5) or a reduced-dose TNX maintenance regimen (10 mg/kg weekly x6, then 20mg/kg monthly; loTNX), with (loTNX+MMF, n=4) or without mycophenolate mofetil (MMF) at 200mg/d po (loTNX, n=4). In 3 sTNX animals therapy was discontinued on day 175. Results were compared to historical data with hu5c8 monotherapy dosed as for loTNX (n=5). Biopsies or explanted hearts were evaluated at three protocol-defined time-points (d45, d90, d180), at earlier explant. Results: sTNX (MST >232d, range 116-305) significantly prolonged cardiac allograft survival relative to hu5c8 alone (MST 133d; p=0.016), loTNX (MST 99d; p=0.014), or loTNX+MMF (MST 88d; p=0.011). All grafts treated with loTNX () or with loTNX+MMF () exhibited acute rejection histologically within 90 days, and 7 of 8 grafts failed before day 180. One sTNX graft rejected at 116d in association with bacterial infection; one graft was electively explanted at 181d; and three grafts survived for 57, 90, and 130 days after discontinuing TNX-1500. Neither sustained thrombocytopenia nor micro- or macro-vascular thrombosis were observed. At 90 days, loTNX+MMF had a significantly higher median ISHLT score (2.0) than sTNX grafts (0.2; p=0.016); loTNX+MMF also had a significantly higher median CAV score (1.8) at d90 than either loTNX (0.2; p=0.022) or sTNX (0.3; p=0.026). At subsequent graft explant or end-of-study biopsy (180d), loTNX+MMF had a higher median CAV score (2.4) than loTNX (0.4; p=0.002) or sTNX (0.8; p=0.002). sTNX suppressed the rise in Teff/Tregs ratio at the final time-point (180d or <180d if graft failure) more effectively than loTNX+MMF (3.5 ± 0.9 vs 9.5 ± 6.1, p=0.031). sTNX (5/5) but not loTNX (1/4) or loTNX+MMF (2/4) consistently prevented anti-donor antibody elaboration. Conclusions: Blockade of CD154 with sTNX monotherapy was not associated with thrombotic events, well tolerated, and consistently prevented pathogenic alloimmunity in this stringent preclinical model. Lower TNX maintenance dosing, with or without MMF, was less effective. *TNX-1500 is a pre-IND molecule and not approved for any clinical indication. NIH grant P01 HL158504. Tonix Pharmaceuticals. RC is supported by the Benjamin Research Fellowship from the German Research Foundation.

The Use of Negative Pressure Wound Therapy After Arterial Vascular Reconstructions

The Use of Negative Pressure Wound Therapy After Arterial Vascular Reconstructions

Two decades of experience in explantation and graft preserving strategies following primary endovascular aneurysm repair and lessons learned.

We aim to scrutinize our evolving re-intervention strategies following primary endovascular aortic aneurysm repair (EVAR) - EVAR GORE SalvAge Fabric Technique (ARAFAT), aortic sac double breasting with endograft preservation, and stent-graft explantation. We performed 1,555 aortic interventions over the study period, including 910 EVARs. Factors associated with the need for reintervention and the likelihood of chronic fabric fatigue failure (CFFF) were investigated. Using conventional and innovative diagnostic modalities with Prone contrASt enHanced computed tomography Angiography (PASHA), 136 endoleaks (ELs) were identified (15 type I, 98 type II; 18 type III; 5 type IV). Forty-four (4.84%) patients underwent re-intervention post-primary EVAR; 18 ARAFATs, 12 double breastings, and 14 explantations. Choice of re-intervention was based on patient fitness and mode of failure. Mean EL detection duration following primary EVAR was 53.3 ± 6.82 months, while mean time to re-intervention was 70.20 ± 6.98 months. The mean sac size before the primary EVAR and re-intervention was 6.00 ± 1.75 cm and 7.51 ± 1.94 cm, respectively. Polyester (61.40%) was the most commonly employed stent-graft material. Use of more than three modular stent-graft components (3.42 ± 1.31, p = 0.846); with the proximal stent-graft diameter of 31.6 ± 3.80 cm (p = 0.651) and the use of iliac limbs more than 17 mm (p = 0.364), all added together are contributing factors. We had one peri-operative mortality following explantation due to sepsis-induced multiorgan failure. Our re-intervention strategies matured from stent graft explantation to graft preservation with endovascular relining of the stent-graft. Graft preservation with aortic sacotomy and double breasting were used to manage concealed ELs due to aortic hygroma.

First case report of gastric outlet obstruction due to aortofemoral bypass Dacron graft erosion of the duodenum treated with neo aortoiliac system procedure.

IntroductionGastric outlet obstruction is an uncommon complication of surgical treatment of aortoiliac occlusive disease with aortofemoral bypass. The most frequent presenting feature of duodenal erosion due to aortic synthetic graft is upper gastrointestinal bleeding, which can range from a minor “herald” bleed to exsanguinating hemorrhage.Case presentationA 64-year-old male patient with an aortofemoral Dacron bypass due to aortoiliac occlusive disease TASC II D with a chronic graft infection required emergency resection of the right limb of the Dacron graft two years ago. The patient developed abdominal pain, postprandial vomiting and progressive weight loss with an upper gastrointestinal endoscopy that showed Dacron graft material eroding into the fourth portion of the duodenum generating a gastric outlet obstruction without aortoenteric fistula and ulceration in the duodenal mucosa.Clinical discussionThe treatment goals of aortoenteric fistula are to control hemorrhage, treat infection, maintain adequate distal perfusion, graft explantation and aortic reconstructions like in this case. Traditional treatment of aortoenteric fistula is graft excision and establishing an anatomic autologous or an extra-anatomic synthetic bypass. Neo aortoiliac system procedure has shown to be the most effective and safest emerging technique today.ConclusionAortoenteric fistula is a life-threatening condition associated with high morbidity and mortality and it can also pose a diagnostic dilemma. There are many presentations of aortoenteric fistula including gastric outlet obstruction syndrome. The neo aortoiliac system procedure is the ideal curative surgical approach in stable patients.

26. A New Regenerative Paradigm for Interval Autologous Cranioplasty: The Cell-Augmented Scaffold-Enhanced (CASE) Cranioplasty

Purpose: Autologous interval cranioplasty has become the standard of care following decompressive craniectomy. Replantation of the stored bone graft has infection and bone resorption rates upwards of 30%. We propose a new paradigm for autologous cranioplasty incorporating novel regenerative techniques that aims to improve fidelity of grafts and reduce infection and resorption. Methods: An IRB-approved cohort of 11 consecutive patients who underwent Cell-Augmented Scaffold-Enhanced (CASE) regenerative cranioplasty were compared to 14 who underwent traditional autologous cranioplasty. All were followed for at least 6 months postoperatively. For the CASE cranioplasty, frozen autologous bone graft was thawed and washed in accordance with institutional protocol. Tenets of standard interval cranioplasty were followed. Cell-augmentation of the autologous bone graft scaffold was performed; channels were created in the diploic space, then packed with a 1:1 mixture of fresh autologous bone graft harvested from surrounding cranium and bone allograft. Traditional technique followed tenets of cranioplasty but without channeling nor cell augmentation. Primary outcome measures included post-operative graft infection, bone resorption after >6 months and need for graft explantation. Patient demographics and operative data were also collected. Quantitative statistics performed include Student’s independent t-test and Χ2 analysis with a significance level set to p = 0.05. Descriptive statistics include relative risks (RR) with 95% confidence interval (95%CI), means and standard deviations (SD). Results: Clinical evaluation for ≥ 6 months postoperatively demonstrated a bone graft infection rate of 0% for CASE subjects versus 14.3% (n=2) for traditional patients; RR for post-operative infection was 1.17 [95%CI 0.94-1.45]. No patients had bone resorption requiring reoperation or explantation from the CASE cohort, while 2 subjects (14.3%) from the traditional cohort required explantation (RR 1.17, 95%CI 0.94-1.45) due to graft infection. There was no statistically significant difference in gender, etiology, interval time from craniectomy to cranioplasty, nor dimension of defect between the groups. CASE subjects were found to be incidentally older (58 years vs 42, p = 0.02). Mean duration of surgery was 221.3min (SD±52.6min) for CASE subjects vs 119.9 (SD±53.6min) for traditional (p<0.01). Conclusion: Cell-Augmented Scaffold-Enhanced cranioplasty represents a safe novel paradigm modification to standard autologous interval cranioplasty technique with reduced rates of post-operative infection and reoperation for explantation.

Thoracic Aortic Graft Salvage after Sternal Wound Infection with Antibiotic Beads and Flap Coverage.

Summary:Infections involving thoracic aortic grafts are difficult to treat and have devastating consequences. The traditional approaches to surgical management include aggressive debridement with graft explantation and replacement. Despite treatment, the reported morbidity and mortality rates are high. The purpose of this study was to present our experience with an innovative approach to aortic graft salvage in the setting of sternal wound infection using antibiotic impregnated polymethylmethacrylate beads followed by definitive wound closure with flap coverage. A retrospective review identified patients with surgical wounds after aortic graft or cardiac valve placement over a 7-year period at a single institution. Patients were treated using an algorithm consisting of repeated surgical debridement and placement of antibiotic beads followed by flap coverage after suppression of the infection. A total of 20 patients were treated for surgical wounds, including 19 sternal and one thoracotomy wound. Culture positive surgical site infections were documented in 16 patients. One patient required a bead exchange before definitive closure. There were no in-hospital mortalities. All but two patients achieved successful infection suppression and wound closure with flap coverage. The use of antibiotic beads with serial debridement and flap closure may offer a valid option for aortic graft salvage in the setting of infected sternal wounds in the appropriate patient population. The proposed algorithm showed that patients may be successfully treated, and their infection suppressed without the need for graft removal. Mortality rates were lower from those previously reported in the literature.

Percutaneous Drainage for Aortic Graft Infection Post-aneurysm Repair: A Viable Option?

PurposeNon-operative management of aortic graft infection is usually only considered in a palliative context. We describe the safety, efficacy, and clinical outcomes of percutaneous drainage of aortic graft infections (AGI) following either open or endovascular repair of aneurysmal disease.MethodsTwelve consecutive patients (11 males, 1 female, mean age 72.7 ± 10.3 years, age range 52-88 years) between January 2010-July 2020 who underwent percutaneous drain insertion in either an infected aortic sac or periaortic abscess cavity following endovascular or open surgical graft repair were identified. Patient and procedural characteristics as well as clinical outcomes were determined.ResultsOf the 12 patients who underwent percutaneous drain insertion, five (41.7%) had undergone open abdominal aneurysm repair, one (8.3%) open thoracoabdominal aneurysmal repair, and six (50%) endovascular abdominal aneurysm repairs. Drain size ranged from 10-20 French. All were inserted under ultrasound (US), computed tomography (CT), and/or fluoroscopic guidance. Median duration of drain placement was 55.2 days (range 3-174). Five patients (41.7%) had the drain in place as a stabilizing bridge until or after definitive surgical explantation and aortic reconstruction. Seven patients (58.3%) were managed with drain placement and antibiotic therapy without surgical intervention. Six (50%) were alive at the most recent time of follow-up (median, 732 days, range 166-1650 days). Three patients (25%) died during follow-up with causes including erosion of aortic reconstruction into sigmoid colon, unrelated chronic obstructive pulmonary disease exacerbation, and severe clostridium difficile colitis and pseudomonal pneumonia (median 1244 days, range 992-1597 days). Three (25%) patients were lost to follow-up. No drain-related complications were noted.ConclusionPercutaneous drainage of AGI following endovascular or open aneurysm repair is a safe and viable management option either as a temporizing measure as a bridge to surgical graft explantation or as a non-surgical therapy for long term management.

Aortic graft explants - A single institution analysis of incidence and outcomes.

Explantation of both endovascular endovascular aneurysm repair and open aortic grafts is a procedure associated with high peri-operative risk, and the current study sought to determine the outcomes and trends over time in these patients. This study examined data from all patients undergoing explant of an aortic graft (both open and endovascular) between January 2004 and December 2020 at a single centre. Variables analysed included comorbidities, duration to and indication for explantation, type of revascularization, in-hospital complications and mortality, duration of hospital and ICU stay, and out-patient mortality. Of 688 open and 1352 EVARs performed, 46 patients underwent 48 explants. Five were open grafts and 43 were endografts, equating to an explant rate of 0.73% of open and 3.18% EVARs. Average time to explant was 70 months, with patients presenting electively having a significantly longer duration to representation than those presenting emergently (51 vs 44 months, p=0.003). Indication for explant was endoleak in 70%, infection in 23%, and occlusion in 6%. Of the endoleaks, 61% of were Type 1, 22% Type II, 11% Type IV, and 6% Type V. On representation, 17 patients (35%) were symptomatic. Overall mortality rate was 8.3%, with a trend for higher mortality in emergent than elective presentations (11.8 vs 6.5%, p=0.55). There was no change in explant rate over time. Elective aortic graft explantation is associated with low mortality, despite its complexity and patient comorbidities. Patients presenting with symptoms suffered higher mortality and a longer post-operative course, suggesting that aortic graft explantation should be considered sooner rather than later, rather than persisting with repeated endovascular management.

Neoaortoiliac system in treating aortic graft infections: a single center long-term experience and review of the literature.

Aortic graft infection represents one of the most challenging and life-threatening complication of surgical and endovascular treatment of aortic pathologies. The aim of this study was to report the results of a single center with in-situ revascularization for the treatment of aortic graft infections using the neo-aorto-iliac system (NAIS) and to review the literature about this surgical technique. We retrospectively reviewed our aortic graft infection case series and in-situ revascularization using the neo-aorto-iliac system. The study was conducted from January 2009 to June 2020. The primary outcomes analyzed were early mortality (<30 days), late mortality (>30 days), reinfection rate. Secondary outcomes were the primary patency rate, the secondary patency rate, and the lower limb salvage rate. A literature review of the last twenty years was performed on international medical databases Pubmed (Medline), Scopus and Web of Science. During study period, 12 patients, all male (median age of 69 years [range: 52-87 years]), underwent to infected graft explantation and revascularization by NAIS using femoral-popliteal veins. Six cases were complicated by aorto-enteric fistulas, five were duodenal and one was colon. Patients spent the immediate postoperative period in the Intensive Care Unit for a median time of 4 days (range: 0-9 days). The median length of hospital stay was 27.5 days (range: 1-66 days). The mean follow-up was 21.5 months (range: 0-120). The 30-day mortality rate was 25% (3 patients) due to postoperative complications. No patient dropped out of the follow-up protocol. The primary patency rate was 92% while the secondary patency rate was 100%. No patient underwent lower limb amputation. Persistence of infection occurred in 1 case (8.3%). Overall Kaplan-Meier survival estimates were 75% for 30 days, 50% for 1 year, 48% for 5 years. Literature analysis identified 19 case series. The literature regarding NAIS has low statistical evidence due to retrospective design of the studies. Our results are in agreement with retrospective studies in the literature. When the surgical team is confident with NAIS, this technique should be considered the preferred method, considering an acceptable and comparable mortality rate with other techniques and a better rate of patency, resistance to graft degeneration, recurrent infections and amputation rate.

Endovascular Repair Of Delayed Endologix AFX Graft Failure Is Superior To Open Repair With Explant

<h3>INTRODUCTION AND OBJECTIVES</h3> Prior studies have described delayed failure of the Endologix Endovascular AAA System (AFX) with resultant aneurysm sac pressurization and increased risk of rupture. While there is no consensus on operative strategy to deal with this endograft failure, options include re-lining with a contemporary endograft or open graft explant. The purpose of this study is to compare these two surgical treatment options in our own single institution experience. <h3>METHODS</h3> A retrospective review was performed of 122 AFX endografts implanted at our tertiary care center from 2013-2019. Thirty-seven patients were found to have delayed endograft failure and subsequently underwent re-line(n=25) or explant(n=12). All re-interventions were performed for endoleak identified on imaging, sac expansion, and/or rupture. Primary composite outcome was successful aneurysm exclusion without mortality at 30-days. Secondary endpoints included hospital length of stay and operative time. Patients without appropriate follow-up were excluded unless death occurred within the perioperative period. <h3>RESULTS</h3> Thirty-seven patients were identified, of which 25 underwent re-line and 12 explant. There were no differences in age, gender, race comparatively(p>0.05), or reason for re-intervention (presence of endoleak, endoleak type, rupture)(p>0.05) There was no significant difference in the primary composite endpoint of successful aneurysm exclusion without death within 30-days between graft re-line(76.0%) and explant(75.0%) (p=0.95). Graft re-line had a significantly shorter hospital length of stay (2.20±2.25d vs. 8.64±7.38d (p<0.01)) and operative time (164.1±110.4min vs. 272.6±113.7min (p=0.01)). Additionally, operative time for the re-line cohort was not significantly different than that of their original EVAR(p=0.29). There were 3(25%) deaths in the explant cohort compared to zero in the re-line cohort although 2(8%) went on to require explant. <h3>CONCLUSIONS</h3> Endograft re-line, although off IFU, does produce analogous aneurysm exclusion rates when compared to explant in Endologix AFX failures, with a reduction in OR time, hospital length of stay and mortality.

Long-term outcomes and interventions of postoperative type 1a endoleak following elective endovascular aortic aneurysm repair.

This study evaluated the incidence and long-term outcomes of postoperative type 1a endoleak (PT1a) following endovascular aortic aneurysm repair (EVAR). A retrospective review of consecutive aortoiliac EVARs performed at a single institution from June 2006 to June 2012 was conducted. Patients with PT1a were identified by postoperative imaging and compared with those who did not develop a PT1a. Late outcomes were also studied of a subset of patients with PT1a who had persistent intraoperative type 1a endoleak (iT1a) on completion angiogram during EVAR that had resolved on initial follow-up imaging. Three hundred eighty-nine patients underwent EVAR with median follow-up of 87months (interquartile range, 64-111months). The incidence of PT1a was 8.2% (n= 32) with a median follow-up of 74months (interquartile range, 52-138months). Compared with the total cohort, those who developed PT1a were statistically more likely to be female (32% vs 17%; P= .03) and have a higher all-cause mortality (71% vs 40%; P< .01) and aneurysm-related mortality (15.6% vs 1.7%; P< .01). Median time to presentation was 52months. Of the 32 patients with PT1a, five (15.6%) presented with aortic rupture, of which three underwent extension cuff placement, one had open graft explant, and one declined intervention. Six patients in total (18.7%) declined intervention; five of these died of nonaneurysmal causes and one remains alive. Of the 26 patients with PT1a who had intervention, 21 (80.7%) showed resolution of PT1a, and five (19.2%) had recurrence. For patients with recurrent PT1a, two had resulting aneurysm-related mortality, two endoleaks resolved after relining with an endograft, and one patient declined intervention but remains alive. Patients with PT1a who had intervention with resolution showed no significant difference in median survival estimates (140.0months) compared with the remaining EVAR cohort (120.0months; P= .80). Within the PT1a cohort, 6 (18.7%) had also experienced iT1a with a mean time to presentation of the late PT1a of 45months. iT1a was associated with a significantly increased likelihood of developing a PT1a (P< .01) and decreased median survival (P< .01), but there was no known aneurysm-related mortality. Development of PT1a following elective EVAR is associated with increased all-cause and aneurysm-related mortality and presents an average of 52months postoperatively. This underscores the importance of long-term surveillance. Patients with PT1a who had a successful intervention showed no significant difference in median survival. Those with iT1a had a higher risk for PT1a compared with the EVAR cohort overall and had decreased median survival, without increased aneurysm-related mortality.

Open surgical conversion and management of patients with ruptured abdominal aortic aneurysm after previous endovascular aneurysm repair

Introduction/Objective. The objective was to present the results and technical considerations from high-volume center when performing late open surgical conversion (LOSC) after endovascular aneurysm repair (EVAR) in ruptured abdominal aortic aneurysm (RAAA) patients. Methods. This was a single center retrospective study. LOSC was performed whenever eventual endovascular reintervention failed, was not feasible due to hostile anatomy and unavailability of specific endograft materials, or when patient was hemodynamically unstable necessitating emergent surgery. Results. All previously implanted EVARs had bimodular configuration with suprarenal fixation. Total endograft explantation was performed in 40% of patients. Hospital mortality was 20%. Both patients who died had total endograft explantation with supraceliac clamp lasting more than 30 minutes. 30-day mortality was 30%, with one more patient who died from pulmonary embolism after hospital discharge and two hospital deaths were due to myocardial infarction. Conclusion. LOSC due to RAAA after previous EVAR carries greater mortality for the patient, suggesting multifactorial impacts on the outcome. The appropriate choice of surgical method and technical success are of ultimate importance, with total graft explantation having negative impact on patient?s survival.

Abdominal aortic endograft infection with Clostridium difficile.

The increase in endovascular aortic aneurysm repair has led to increasing incidence of aortic endograft infections. Additionally, more atypical organisms are being identified as pathogens. We report on a rare aortic endograft infection to further characterize and understand these infections. We report a Clostridium difficile culture-positive aortic endograft infection in an 82-year-old male 3years after endovascular abdominal aortic aneurysm repair. The patient underwent successful open, complete explant of his endograft and in-situ repair using a rifampin-soaked Dacron graft. He continues to do well. Aortic endograft infections are a complex problem further complicated by rare and virulent infections. Unless the patient is at prohibitive risk, the management of infected aortic endografts is surgical graft explant and in-situ or extra-anatomic reconstruction due to the exceedingly high mortality rate with non-operative management.

EP.WE.962Pre-emptive arterial stenting with covered vascular stents to prevent mycotic haemorrhage in infected fields following failed kidney and pancreas transplants prior to graft explant

Abstract Aims Allograft nephrectomy and pancreatectomy present a significant surgical challenge in contaminated surgical fields, with risks of post-operative pseudoaneurysms and mycotic bleeds. We report on our experience of prophylactic endovascular stenting shortly before or after allograft nephrectoym and pancreatectomy to reduce the risk of subsequent pseudoaneurysm formation from the donor arterial conduit. Methods A retrospective analysis of all patients undergoing arterial stenting by interventional radiology prior to graft explant in our unit was performed. Results Twelve patients were identified, 6 of whom had undergone kidney transplant and 6 simultaneous pancreas kidney transplant (SPK) with an average age of 46. Iliac stenting was prophylactic in 7 patients, for pseudoaneurysm (28%), graft pancreatitis (28%), acute rejection (28%), enteric anastomotic leak (16%) and transplant pyelonephritis (14%). Therapeutic stenting was performed in 5 patients, all of whom had ruptured pseudoaneurysms. Post-operative 30-day mortality occurred in 1 patient resulting from an acute on chronic limb ischaemia and subsequent sepsis and death. Of the remaining patients, none experienced complications from stenting. 9 of the 12 stented patients remain alive, with the 3 mortalities resulting from other pathology not relating to stenting. Conclusion Prophylactic iliac stenting around the time of graft excision in inflamed or infected fields provides a safe and effective technique to completely exclude the donor arterial stump, with no subsequent vascular complications reported within our series. Preventing mycotic aneurysm formation in this way may mitigate the risk of potentially catastrophic post-operative mycotic arterial bleeds.

Histologic Analysis of Porcine Dermal Graft Augmentation in Treatment of Rotator Cuff Tears

Background: Biologic augmentation via extracellular matrix (ECM) scaffolds has been utilized to address rotator cuff tears with poor-quality tissue. Purpose: To evaluate the cellular changes in graft explants taken from patients treated with porcine dermal grafts for rotator cuff tears. Study Design: Case series; Level of evidence, 4 Methods: Four graft biopsy specimens were obtained from patients treated with porcine dermal grafts in an interposition technique for rotator cuff tears and compared with a nonimplanted graft and a normal rotator cuff specimen. Biopsy of the graft site was performed at 18 days, 3 months, 7 months, and 10.5 months after implantation. Hematoxylin and eosin staining was used to evaluate for cellular and vascular changes. Picrosirius red (PSR) stain with 90° polarized light was performed to evaluate collagen fibril size and orientation. All biopsy specimens were analyzed by a pathologist. Results: There was evidence of progressive remodeling of the porcine dermal grafts. The most mature grafts demonstrated vessel infiltration and extensive remodeling without evidence of inflammation, foreign body reaction, or tissue rejection. PSR demonstrated increased organization of collagen domains, resembling normal tendon by 10.5 months postoperatively. Conclusion: This series suggests that ECM grafts may serve as an effective scaffold for host cell infiltration, collagen reorganization, and vascularization as a result of histologic changes demonstrated with retrieval of specimens from patients with rotator cuff tears that were augmented with porcine dermal grafts.

705 Aortic Graft Infection Managed with Bovine Patch, A Case Report and Literature Review

Abstract Aim to describe good outcomes in a case with Aortic graft infection (AGI) managed with Bovine patch and outline management of AGI. Method Literature review utilising keywords ‘’Aortic graft infection’’AND’’Bovine Patch’’ revealed initially 1350 articles, all studies in English were included, all duplicates were removed, screening was performed using the PRISMA flow. To correlate with the findings, we followed up a 72-year-old patient who presented with aortic graft infection followed by graft explantation and a fashioned Bovine graft insertion and followed up for 1 year for any re-infection in the clinics. Results Literature search resulted 73 articles discussing the role of Bovine Patch as a choice in prevention of Aortic graft re-infection. In our case, there was no clinical nor radiological evidence of Bovine patch re-infection for over a year. Literature review showed that AGI is a rare but serious complication with mortality up to 60%.The main management is IV antibiotics, followed by graft explantation and consideration of re-implantation of various types of grafts. The European society of vascular surgery (ESVS) guidelines recommend re-implantation with an aortic antibiotic soaked graft, yet re-infection rate is quoted at 20%. however, in our case Bovine graft was free from re-infection at 1 year follow up. Conclusions IV anitbioics and explantation remain the mainstay for treatment of aortic grafts infection, however, there is increasing evidence that Bovine grafts show excellent freedom from re-infection at follow up. Hence, this might be the conduit of choice when performing such surgeries; however, more evidence is needed.

Prediction of Major Adverse Events After Endovascular Aneurysm Repair Using a Machine Learning Model

Predicting major adverse events (MAE), including type I and III endoleaks (ELs), after endovascular aneurysm repair (EVAR) is essential for clinical decision-making. No clinical decision instruments can reliably predict for MAE after EVAR. We developed a machine learning model (MLM) for predicting MAE within 3 years after elective EVAR using preoperative demographic information and aneurysm geometry. MLMs infer complex interaction without prespecification, possibly increasing the prediction accuracy compared with logistic regression models (LRMs). Patients with intact infrarenal abdominal aortic aneurysms who had undergone EVAR with preoperative M2S reconstruction from 2010 to 2017 at a single institution were analyzed. The MAEs included aneurysm- or intervention-related death within 30 days, aneurysm rupture, the development of type I or III ELs, greater than three reinterventions, or EVAR explantation. Patients with <3 years of follow-up were excluded. Seventy-four preoperative predictors were evaluated. Of these, 30 were geometric factors derived from M2S models. The remaining factors were demographic. The performance of LRMs, random forest models (RFMs), and gradient-boosted models (GBMs) were evaluated using a 75% and 25% training and testing split, fivefold cross-validation, and receiver operating characteristic performance metric. A total of 250 patients were included (mean age, 71.9 ± 8.6 years; 86% male). The abdominal aortic aneurysm diameter was 56.0 ± 10.6 mm, and the infrarenal neck length was 24.6 ± 4.5 mm. Of the 250 patients, 40 (16%) had experienced MAE: 11 had died within 30 days, 3 had experienced aneurysm rupture, 10 had developed a type I EL, 10 had developed a type III EL, 10 had required graft explantation, and 4 had undergone four or more reinterventions. The most significant 45 predictive variables are shown in the Fig. All discrimination and calibration metrics favored the MLM over the LRM. The area under the curve for the LRM was 0.70 compared with 0.83 for the RFM and 0.77 for the GBM. The LRM classification accuracy was 68% compared with 84% for the RFM and GBM. The GBM showed superior calibration performance (Hosmer-Lemeshow P = .201). The removal of the geometric parameters significantly degraded the performance for all the models (likelihood ratio P < .001). The MLM displayed superior discrimination and calibration compared with the LRM in predicting MAE for the first 3 years after elective EVAR, possibly owing to the complex interaction terms in the predictive factors. The anatomic characteristics were more influential than the demographic data in predicting for MAE. Our MLM might predict for MAE after EVAR and thereby aid in selecting patients for EVAR, nonoperative observation, or open repair.