Mycotic Abdominal Aortic Aneurysms - A Tertiary Centre Experience and Formulation of a Management Protocol

Prognostic factors after open and endovascular repair for infected native aneurysms of the abdominal aorta and common iliac artery

OBJECTIVE

Infected native aneurysms (INAs) of the abdominal aorta and iliac arteries are uncommon, but potentially fatal. Endovascular aneurysm repair (EVAR) has recently been introduced as a durable treatment option, with outcomes comparable to those yielded by conventional open repair. However, owing to the rarity of the disease, the strengths and limitations of each treatment remain uncertain. The present study aimed to separately assess post-open repair and post-EVAR outcomes and to clarify factors affecting the short-term and late prognosis after each treatment.

METHODS

Using a nationwide clinical registry, we investigated 600 patients treated with open repair and 226 patients treated with EVAR for INAs of the abdominal aorta and/or common iliac artery. The relationships between preoperative or operative factors and postoperative outcomes, including 90-day and 3-year mortality and persistent or recurrent aneurysm-related infection, were examined.

RESULTS

Prosthetic grafts were used in >90% of patients treated with open repair, and in situ and extra-anatomic arterial reconstruction was performed in 539 and 57 patients, respectively. Preoperative anemia and imaging findings suggestive of aneurysm-enteric fistula were independently associated with poor outcomes in terms of both 3-year mortality (hazard ratio [HR], 1.62; 95% confidence interval [CI], 1.01-2.62; P = .046, and HR, 2.24; 95% CI, 1.12-4.46; P = .022, respectively) and persistent or recurrent infection (odds ratio [OR], 2.16; 95% CI, 1.04-4.49; P = .039, and OR, 4.96; 95% CI, 1.81-13.55; P = .002, respectively) after open repair, whereas omental wrapping or packing and antibiotic impregnation of the prosthetic graft for in situ reconstruction contributed to improved 3-year survival (HR, 0.60; 95% CI, 0.39-0.92; P = .019, and HR, 0.53; 95% CI, 0.32-0.88; P = .014, respectively). Among patients treated with EVAR, abscess formation adjacent to the aneurysm was significantly associated with the occurrence of persistent or recurrent infection (OR, 2.24; 95% CI, 1.06-4.72; P = .034), whereas an elevated preoperative white blood cell count was predictive of 3-year mortality (HR, 1.77; 95% CI, 1.00-3.13; P = .048).

CONCLUSIONS

Profiles of prognostic factors differed between open repair and EVAR in the treatment of INAs of the abdominal aorta and common iliac artery. Open repair may be more suitable than EVAR for patients with concurrent abscess formation.

A Comparison of Surgical Techniques and Outcomes for Primary Infected Abdominal Aortic Aneurysms

BACKGROUND

Primary infected abdominal aortic aneurysms (PIAAAs) are associated with high morbidity and mortality. Three repair approaches include open in-situ repair (OIR), extra-anatomic repair (EAR), and endovascular abdominal aortic aneurysm repair (EVAR). This study is one of the largest single-center case series comparing the outcomes of the different surgical approaches for PIAAA.

METHODS

This is a retrospective cohort study of all patients treated surgically for PIAAA between 2000 and 2021. PIAAA diagnosis was defined as the presence of an abdominal aortic aneurysm with evidence of infection on clinical presentation, laboratory markers, radiology, or surgically. Patients with prior aortic surgery were excluded from this study. Basic demographics were compared across the 3 surgical groups using standard statistical methods. Our primary outcomes included mortality at 1 and 5 years. Kaplan-Meier curves were generated and compared using log-rank testing. Multivariate Cox proportional hazards models were created to assess determinants of mortality.

RESULTS

A total of 43 patients were included in the full cohort. Patients undergoing EVAR more often had diabetes, end-stage renal disease, and coronary artery disease. EVAR was also more often done in patients with a saccular aneurysm rather than fusiform. (93% vs. 70% in EAR and 42% in OIR; P = 0.015). All-cause mortality rates at 1 year were not significantly different between the 3 groups. Survival at 5 years did show a significant benefit of OIR over EVAR and EAR: OIR had an 8% mortality rate with EAR having a 53% rate and EVAR having the highest (72%) mortality rate at 5 years (P = 0.03). Multivariable Cox regression analysis showed that EVAR (aHR 12.1, (95% CI 1.42 to 103.9), P = 0.02) and EAR (aHR 15.1, (95% CI 1.59 to 143.3), P = 0.0.02) had an increased 5-year mortality risk when compared to OIR.

CONCLUSIONS

Repair of primary infected aortic aneurysm is associated with high complication and mortality rates regardless of the approach. In our studied sample, OIR offered an improved long-term survival without added benefits in terms of complication rates. In infected AAA, EVAR should be considered bridging stage between the urgent situation and eventual open repair.

Contemporary Outcomes of Endovascular and Open Surgical Repair for Mycotic Aortic Aneurysms: A Systematic Review

BACKGROUND

To perform a systematic review on contemporary outcomes of endovascular repair and open surgical repair (OSR) for the treatment of mycotic aortic aneurysm (MAA).

METHODS

A comprehensive literature search on the management of MAAs with endovascular repair or OSR was performed between January 1998 and January 2023. Patient demographics, early and late outcomes were analyzed with respect to treatment modality and MAA location.

RESULTS

Forty-eight articles were included, encompassing a total of 1,358 patients (75.8% male; mean age 66.9 years; 1,372 aneurysms) treated by open (49.8%) or endovascular (50.2%) repair. Salmonella spp., and Staphylococcus spp. were the most prevalent pathogens in Asian and European countries respectively. An increasing number of descending thoracic MAAs were managed by endovascular repair (27.9% vs. 12.8%). Early mortality rates for supra- and infra-renal MAAs managed by endovascular repair were lower than OSR (suprarenal 5.4% vs. 43.2%; infrarenal 1.8% vs. 16.7%). Overall, endovascular repair demonstrated lower intraoperative (1.0% vs. 1.8%) and early mortality (6.5% vs. 15.9) rates than OSR. However, endovascular repair was associated with higher late sepsis rate (5.7% vs. 0.9%) and reintervention rate (17.6% vs. 7.3%). Pooled survival rates at 1- and 5-year were similar between the 2 groups.

CONCLUSIONS

Current literature suggest that endovascular repair is an effective and safe alternative to OSR for descending thoracic, suprarenal, and infrarenal MAAs. However, endovascular repair is associated with higher risk of infection-related complications and reintervention during follow-up.

Surgical Outcomes of Infective Native Aortoiliac Aneurysms in a Chilean Academic Center

BACKGROUND

Infective native aortic aneurysms (INAAs), formerly called mycotic aneurysms, remain an uncommon disease with significant heterogeneity among cases; hence, there is lack of solid evidence to opt for the best treatment strategy. The present study aims to describe a 20-year experience at a single institution treating this uncommon condition.

METHODS

Retrospective study of all patients treated for INAA at a single academic hospital in Santiago, Chile, between 2002 and 2022. Clinical characteristics are described, as well as operative outcomes per type of treatment. Nonparametric Mann-Whitney U-test or Kruskal-Wallis tests were performed when appropriate, and results were reported as median and ranges. Survival at given timeframes was determined by a Kaplan-Meier curve, with analysis performed through a Cox regression model.

RESULTS

During the study period, 1,798 patients underwent aortic procedures at our center, of which 35 (1.9%) were treated for INAA. Of them, 25 (71.4%) were male. One patient had 2 INAAs. Median age was 69.5 years (range: 34-89 years). Of the 36 INAAs, the most frequent location was the abdominal and thoracic aorta in 20 (55.5%) and 11 (30.5%) cases, respectively, followed by the iliac arteries in 4 (11.1%) cases. One (2.7%) patient presented a thoracoabdominal INAA. Overall, endovascular treatment associated with long-term antibiotics was used in 20 (57.1%) patients: 4 of them underwent hybrid treatment. Fifteen (42.8%) patients underwent direct aortic debridement followed by in situ or extra anatomic revascularization. There was a significant difference in age between both treatment strategies (a median of 76.5 years for endovascular versus a median of 57 years for open, P = 0.011). The median hospital stay was 15 days (range: 2-70 days). The early complications rate (<30 postoperative days) was 20% (n = 7). Early mortality rate (inhospital or before postoperative 30 days) was 14.2% (n = 5). Median follow-up was 33 months (range: 6-216 months). The overall survival rates at 1, 3, and 5 years were 69.9% (standard error [SE] 8.0), 61.7% (SE 9.8), and 50.9% (SE 11.8), respectively. Five-year survival rate of patients undergoing endovascular treatment compared with open approach was 45.9% (SE 15.1) versus 80.0% (SE 17.8), respectively (P = 0.431). There were no significant differences in survival between open and endovascular treatment, hazard ratio 3.58 (confidence interval 95%: 0.185-1.968, SE ± 0.45 P = 0.454).

CONCLUSIONS

Patients treated by endovascular approach were older than patients treated by open approach. Even though, the open group had a higher 5-year survival rate than the endovascular group, not statically significance differences were found between treatments.

Abdominal Aortic Occlusion and the Inflammatory Effects in Heart and Brain

Background

Abdominal aortic occlusion (AAO) occurs frequently and causes ischemia/reperfusion (I/R) injury to distant organs. In this study, we aimed to investigate whether AAO induced I/R injury and subsequent damage in cardiac and neurologic tissue. We also aimed to investigate the how length of ischemic time in AAO influences reactive oxygen species (ROS) production and inflammatory marker levels in the heart, brain, and serum.

Methods

Sixty male C57BL/6 mice were used in this study. The mice were randomly divided into either sham group or AAO group. The AAO group was further subdivided into 1-4 hr groups of aortic occlusion times. The infrarenal abdominal aorta was clamped for 1-4 hr depending on the AAO group and was then reperfused for 24 hr after clamp removal. Serum, hippocampus, and left ventricle tissue samples were then subjected to biochemical and histopathological analyses.

Results

AAO-induced I/R injury had no effect on cell necrosis, cell apoptosis, or ROS production. However, serum and hippocampus levels of malondialdehyde (MDA) and lactate dehydrogenase (LDH) increased in AAO groups when compared to sham group. Superoxide dismutase and total antioxidant capacity decreased in the serum, hippocampus, and left ventricle. In the serum, AAO increased the level of inducible nitric oxide synthase (iNOS) and decreased the levels of anti-inflammatory factors (such as arginase-1), transforming growth factor- β1 (TGF-β1), interleukin 4 (IL-4), and interleukin 10 (IL-10). In the hippocampus, AAO increased the levels of tumor necrosis factor (TNF-α), interleukin 1β (IL-1β), interleukin 6 (IL-6), IL-4, and IL-6, and decreased the level of TGF-β1. In the left ventricle, AAO increased the level of iNOS and decreased the levels of TGF-β1, IL-4, and IL-10.

Conclusions

AAO did not induce cell necrosis or apoptosis in cardiac or neurologic tissue, but it can cause inflammation in the serum, brain, and heart.

Endovascular Treatment for Isolated Infected Iliac Artery Aneurysms

PURPOSE

Isolated infected iliac artery aneurysms (IIIAAs) are extremely rare, life-threatening, and intractable. This study aimed to evaluate the outcomes of endovascular treatment in patients with IIIAAs.

METHODS

A retrospective study was conducted for all patients who underwent endovascular treatment for IIIAAs between June 2012 and June 2022 in 3 hospitals. The clinical data and follow-up outcomes were reviewed and assessed.

RESULTS

Fifteen patients were included in this study. The median age was 69 years, 12 patients (80%) were men, and 8 (53%) had hypertension. Most of the patients presented with abdominal or lumbar pain (87%) and fever (60%). The offending pathogen was identified in 11 patients (73%). Fifteen patients had a total of 16 IIIAAs, with 12 (75%) involving the common iliac artery. The immediate technical success rate was 100%, and the 30-day mortality was 7%. Infection-related complications occurred in 2 patients (13%) during hospitalization who were treated by open surgery at a later stage. The median follow-up was 23 months (range: 6-80 months, mean: 32 ± 25 months). Aneurysm recurrence was identified in one patient (7%) 5 months after endovascular repair. It was managed by endovascular stent-graft repair with percutaneous catheter drainage. No patients died during the follow-up period.

CONCLUSION

Endovascular treatment is feasible, safe, and effective for patients with IIIAAs, achieving acceptable clinical outcomes. Infection surveillance with essential reintervention should be considered for potential infection-related complications.

CLINICAL IMPACT

This study first reported that 15 patients underwent endovascular treatment for primary isolated infected iliac artery aneurysms (IIIAAs). It showed a good early and midterm outcomes. This is the first and largest multi-center study and the first literature review of IIIAAs. It provides an evidence that endovascular treatment is feasible, safe, and effective to treat IIIAAs. It suggests endovascular treatment is a promising alternative or a bridge to conventional open surgery for IIIAAs. This may promote endovascular therapy in the management of IIIAAs. It would help clinicians to make an appropriate treatment choice for IIIAAs.