Systematic Review and Meta: Analysis of Aortic Graft Infections following Abdominal Aortic Aneurysm Repair

Transplantation of cryopreserved cardiovascular homografts

Due to degeneration, homografts were since the 1950s only used strictly for replacement of complex arterial segments and lesions incl. the aortic valve, replacement of infected arterial prostheses, and vascular access for patients on haemodialysis. During the 1990s, rate-differentiated freezing methods and anti-crystallization agents proved to prevent crystallisation, and more widespread use with expanded indications incl. coronary and lower limb bypasses began justified by promising midterm results. In 2021, the first Scandinavian homograft biobank was founded in Odense in Denmark. This review summarises the history and the experiences from this biobank.

[Silver Ion Decreases Foreign Body Reaction and Venous Neointimal Hyperplasia through the Inhibition of Interleukin-33 Expression]

INTRODUCTION

Vascular prosthetic grafts are widely used in vascular surgery; however, graft infection remains a major concern. Silver-coated vascular grafts have demonstrated anti-infection properties in clinical settings; however, whether the silver irons influence foreign body reaction or neointimal hyperplasia remains unclear.

METHODS

Sodium alginate and hyaluronic acid (SA/HA) hydrogel patches loaded with rhodamine, with or without silver, were fabricated. Patches were implanted in the subcutaneous or abdominal cavity and inferior vena cava of rats. Samples were harvested on day 14 and examined via immunohistochemical and immunofluorescence analyses.

RESULTS

Silver hydrogel was found to decrease the foreign body reaction; after subcutaneous and abdominal cavity implantation in rats, the capsule was found to be thinner in the silver hydrogel group than in the control hydrogel group. The silver hydrogel group had fewer CD68-positive cells and proliferating cell nuclear antigen and interleukin-33 (IL-33) dual-positive cells than the control hydrogel group. Additionally, the silver hydrogel patch reduced the neointimal thickness after patch venoplasty in rats, and the number of IL-33- and IL-1β-positive cells was lower than that in the control patch.

CONCLUSION

Silver-loaded SA/HA hydrogel patches decreased the foreign body reaction and venous neointimal hyperplasia in rats by the inhibition of IL-33 expression.

Utility of multimodal molecular imaging in the diagnosis and decision-making in arterial diseases

Arterial diseases are prevalent in the general population, particularly in the elderly, and they are among the main causes of morbidity and mortality worldwide. Nuclear imaging is a useful tool in diagnosis and follow-up in different areas of medicine, and over the last 2 decades, these study modalities have become more relevant in the field of angiology and vascular surgery due to their potential benefit in the interpretation of pathophysiological mechanisms associated with the natural history and severity of diseases that affect the circulation such as vasculitis, degenerative aortic aneurysms (AA), peripheral arterial disease (PAD), and complications following reconstructive procedures such as graft infections. The literature has shown evidence of an important number of radiotracers for specific molecules involved in the activity of these entities and their utility as predictors during surveillance and possible therapeutic targets. The present narrative review aims to describe the use of nuclear medicine, imaging methods, and radiotracers that have been applied in arterial diseases, as well as the advantages and considerations, their importance in the diagnosis and follow-up of these complex groups of patients, and future perspectives.

Surgical management of abdominal aortic graft infection: network meta-analysis

BACKGROUND

A paucity of evidence exists regarding the optimal management for abdominal aortic graft infection. The aim of this paper was to assess short- and long-term outcomes following different surgical options in aortic graft infection patients.

METHODS

Medline, Embase and the Cochrane Library were searched from inception to February 2023. Network meta-analysis was performed using a frequentist method. Patients were divided into four treatment groups: complete graft removal with in situ repair, complete graft removal with extra-anatomic repair, partial graft removal with in situ repair and partial graft removal with extra-anatomic repair. The mortality rate at 30-days and 1-year was the primary outcome. Secondary outcomes were longer-term mortality rate, primary patency and reinfections. For included RCTs, the Cochrane risk-of-bias tool was utilized to assess the risk of bias. The methodological quality of cohort studies was evaluated using the Newcastle-Ottawa scale.

RESULTS

Among 4559 retrieved studies, 22 studies with 1118 patients (11 multi-arm and 11 single-arm studies) were included. Patients received complete graft removal with in situ repair (N = 852), partial graft removal with in situ repair (N = 36), complete graft removal with extra-anatomic repair (N = 228) and partial graft removal with extra-anatomic repair (N = 2). Both network meta-analysis results and pooled results of multi- and single-arm cohorts indicated that partial graft removal with in situ repair has the lowest 30-day and 1-year mortality rates (0% and 6.1% respectively), followed by complete graft removal with in situ repair (11.9% and 23.8% respectively) and complete graft removal with extra-anatomic repair (16.6% and 41.4% respectively). In addition, complete graft removal with in situ repair had a lower 3-year (complete graft removal with in situ repair versus complete graft removal with extra-anatomic repair: 32.1% versus 90%) and 5-year (complete graft removal with in situ repair versus complete graft removal with extra-anatomic repair: 45.6% versus 67.9%) mortality rate when compared with complete graft removal with extra-anatomic repair. Patients in the complete graft removal with in situ repair group had the lowest reinfections (8%), followed by partial graft removal with in situ repair (9.3%) and complete graft removal with extra-anatomic repair (22.4%).

CONCLUSION

Partial graft removal with in situ repair was associated with lower 30-day and 1-year mortality rates when compared with complete graft removal with in situ repair and complete graft removal with extra-anatomic repair. Partial graft removal with in situ repair might be a feasible treatment for specific aortic graft infection patients.

Clinical outcome of graft removal versus preservation in abdominal aortic graft infection: a systematic review and meta-analysis

Purpose

The purpose of this study was to compare the clinical outcomes of abdominal aortic graft infection (AGI) treated with removal of the graft vs. graft preservation.

Methods

The electronic databases PubMed, Embase, and Cochrane Library for studies that reported on AGI were searched. Observational studies and case series of at least 10 cases that reporting on the prevalence, microbiology, and outcomes of AGI were included.

Results

Our search identified 23 studies that met our inclusion criteria, reporting on a total of 873 patients who underwent open surgical repair (OSR) or endovascular aneurysm repair (EVAR). Of these patients, 833 received graft removal, and 40 received graft preservation. The prevalence of AGI was reported to be 1.0% (95% confidence interval [CI], 0.5%-1.8%) after OSR and 0.4% (95% CI, 0%-1.1%) after EVAR. The pooled estimates of 1-year, 2-year, and 5-year mortality were 28.7% (95% CI, 19.4%-38.8%), 36.6% (95% CI, 24.6%-49.5%), and 51.8% (95% CI, 38.4%-65.1%) in the graft removal group and 16.1% (95% CI, 4.1%-32.2%), 18.5% (95% CI, 5.7%-35.1%), and 50.0% (95% CI, 31.6%-68.4%) in the graft preservation group. The 30-day mortality rate's risk ratio (RR) for graft removal vs. preservation was 0.98 (95% CI, 0.40-2.38), while the 1-year mortality rate's RR was 3.44 (95% CI, 1.60-7.42).

Conclusion

The 30-day mortality rate of AGI treatment was found to be high, whether using graft removal or preservation. In selected patients, implementing antibiotics with graft preservation as an initial management may be helpful in reducing the mortality rate.

Management and Outcome of Non-Aneurysmal Primary Aortic Infection

INTRODUCTION

Aortic infection without prior intervention or aneurysm is exceedingly rare. We report the presentation, diagnosis, management, and outcome of patients with this unusual entity.

METHODS

Retrospective chart and imaging review of patients with primary aortic infection.

RESULTS

5 patients (3 male, mean age 71.2 years) presented between 2014 and 2022. All had abdominal, back, or flank pain. Four had constitutional symptoms. All were evaluated with a complete blood count; 3 had leukocytosis. Both serum C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) were elevated in the 4 patients evaluated with these tests. All were studied with peripheral blood culture on the first hospital day prior to any antibiotic administration. Blood culture was positive in only 1 patient. Computed tomography (CT) scan showed periaortic inflammation without aneurysm in all. Fluorodeoxyglucose positron emission tomography (PET) was obtained in 3 and a radiolabeled leukocyte single-photon emission CT (SPECT) scan was performed in 2. All demonstrated periaortic concentration of the radioisotope consistent with inflammation or infection. Intraoperative cultures were positive in 3. One patient who had a negative intraoperative culture was examined with broad range polymerase chain reaction (PCR) and DNA sequencing which identified a causative bacterium. The other patient with a negative intraoperative culture had periaortic abscess but was on antibiotics preoperatively, potentially confounding the culture. All patients underwent in-situ repair with rifampin impregnated polyester (N = 2), cryopreserved aortic allograft (N = 2), or autogenous femoral vein (N = 1). No patient developed recurrent infection or aortic related complications following surgery with an average follow up of 31.8 months (range 8-88 months).

CONCLUSIONS

Patients with primary aortic infection present similarly with the triad of abdominal or back pain, laboratory markers of infection, and imaging demonstrating periaortic inflammation. Patients were treated successfully with in-situ repair. Preoperative identification of a causative organism was difficult, and PCR may be useful to help identify an organism.

Robotic-assisted closed-chest management of a fungal-infected prosthetic aortic graft: a case report

Background

Fungal prosthetic graft infections are associated with high mortality, typically requiring aggressive surgical debridement. We present an alternative, minimally invasive approach to address these challenging clinical cases.

Case presentation

A 76-year-old Caucasian male with prior aortic root and arch replacement presented with localized chest wall tenderness after being hit by a car door. Computed tomography angiogram incidentally identified fluid in the anterior mediastinum, surrounding his ascending aortic graft. Rather than undertaking a high-risk reoperative sternotomy and redo complex aortic reconstruction, we elected to proceed with a robotic-assisted, minimally invasive debridement of the aortic graft, coupled with an omental wrap, entirely within the closed chest. Microbiology was positive for Aspergillus species. The patient made an uncomplicated recovery and was discharged home on antifungal therapy, likely to continue indefinitely.

Conclusions

Infected prosthetic aortic grafts can be successfully managed with debridement and pedicled omental flap coverage via a minimally invasive approach within the closed chest, obviating the morbidity of a complex reoperative open procedure.

Aortitis - An Interdisciplinary Challenge

The term 'aortitis' comprises a heterogeneous spectrum of diseases, with varied etiology and clinical presentations, whose common characteristic is the inflammation of the aortic wall. Since aortitis can mimic almost all common cardiovascular disorders, its clinical recognition remains a challenge. Some cases of aortitis remain undetected for a long time and may be diagnosed after severe life-threatening complications have already arisen. The diagnosis of aortitis is based on the presence of homogeneous circumferential thickening of the aortic wall detected on aortic imaging, or typical histological features in combination with clinical findings and laboratory parameters. Management of aortitis is usually conservative (immunosuppressive drugs in noninfectious aortitis; antimicrobial drugs in infectious). However, if vascular complications such as aortic aneurysm, rupture, or steno-occlusive events appear, aortic surgery or endovascular therapy may be required. This review article summarizes the current knowledge regarding the etiology, clinical presentation, diagnosis, and treatment of inflammatory diseases of the aorta to promote better clinical management of these entities.

Abdominal aortic aneurysms part two: Surgical management, postoperative complications and surveillance

Large, symptomatic and ruptured abdominal aortic aneurysms are usually treated surgically if patients are deemed fit enough. This may be achieved through endovascular or open surgical repair. The type of treatment that a patient receives is dependant on many factors, such as the rupture status of the aneurysm. Each approach is also associated with different risks and postoperative complications. Multiple guidelines exist to inform the surgical management of abdominal aortic aneurysms. This literature review combines these recommendations and explores the evidence upon which they are based. In addition, it highlights the key perioperative considerations that need to be considered in cases of unruptured and ruptured abdominal aortic aneurysms.

Surgical and medical interventions for abdominal aortic graft infections

BACKGROUND

Abdominal aortic graft infections are a major complication following abdominal aortic aneurysm surgery, with high morbidity and mortality rates. They can be treated surgically or conservatively using medical management. The two most common surgical techniques are in situ replacement of the graft and extra-anatomical bypass. Medical management most commonly consists of a course of long-term antibiotics. There is currently no consensus on which intervention (extra-anatomical bypass, in situ replacement, or medical) is the most effective in managing abdominal aortic graft infections. Whilst in emergency or complex situations such as graft rupture surgical management is the only option, in non-emergency situations it is often personal preference that influences the clinician's decision-making.

OBJECTIVES

To assess and compare the effects of surgical and medical interventions for abdominal aortic graft infections.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase, and CINAHL databases and WHO ICTRP and ClinicalTrials.gov trials registers to 2 December 2019. We also reviewed the bibliographies of the studies identified by the search and contacted specialists in the field and study authors to request information on any possible unpublished data.

SELECTION CRITERIA

We aimed to include all randomised controlled trials that used surgical or medical interventions to treat abdominal aortic graft infections. The definitions of abdominal aortic graft infections were accepted as presented in the individual studies, and included secondary infection due to aortoenteric fistula. We excluded studies presenting data on prosthetic graft infections in general, unless data specific to abdominal aortic graft infections could be isolated.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed all studies identified by the search. We planned to independently assess risk of bias of the included trials and to evaluate the quality of the evidence using the GRADE approach. Our main outcomes were overall mortality, amputation, graft re-infection, overall graft-related complications, graft-related mortality, acute limb ischaemia, and re-intervention.

MAIN RESULTS

We identified no randomised controlled trials to conduct meta-analysis.

AUTHORS' CONCLUSIONS

There is currently insufficient evidence to draw conclusions to support any treatment over the other. Multicentre clinical trials are required to compare different treatments for the condition.