Morphology of Abdominal Aortic Aneurysms and Correlation with Biomechanical Tests of Aneurysmal Wall Fragments.

BACKGROUND: Evaluate how specific morphologic aspects of abdominal aortic aneurysms (AAAs), including asymmetries, curvatures, tortuosities, and angulations, among others can influence the intrinsic biomechanical properties of the AAA's wall. This study analyzed the correlation of geometric measurements (1-dimensional, 2-dimensional, and 3-dimensional) of preoperative tomographic images of AAA with uniaxial biomechanical tests of the arterial wall fragments of these AAA obtained in open surgical repair of aneurysms. METHODS: It was a multicenter, experimental, and observational study, and initially 54 individuals were selected who underwent open surgical of AAA, with valid biomechanical tests of the anterior wall of the AAA. Seven individuals were excluded because they had poor preoperative quality computed tomography scans and/or artifacts that impeded image segmentation and extraction of AAA geometric indices. The aortic fragments were subjected to uniaxial biomechanical destructive tests to obtain the following data: maximum load, failure stress, failure tension, failure strain energy, strain, and fragment thickness. In the same patients, preoperative computed tomography scans were performed with the extraction of 26 geometric indices, subdivided into 9 1-dimensional indices, 6 2-dimensional indices, and 11 3-dimensional indices. Data were subjected to statistical analysis using SPSS version 28. RESULTS: Comparing ruptured and unruptured AAA, no statistical difference was observed between the biomechanical and geometric parameters. The fragment thickness of the ruptured AAA was lower than that of the unruptured AAA (P < 0.05). By comparing tomographic geometric indices and biomechanical parameters of the aortic fragments using Pearson's coefficient, positive and linear correlations (P < 0.05) were observed between the geometric variable maximum diameter (Dmax) of the AAA with maximum load (r = 0.408), failure tension (r = 0.372), and failure stress (r = 0.360). Positive and linear correlations were also observed between the variable diameter/height ratio (DHr) and the maximum load (r = 0.360), failure tension (r = 0.354), and failure stress (r = 0.289). The geometric variable DHr was dependent and correlated with Dmax. Simple regression analysis showed that R2 varied between 8.3% and 16.7%, and all models were significant (P < 0.05). CONCLUSIONS: Dmax and DHr were linearly and positively correlated with the resistance parameters (maximum load, failure tension, and failure stress) of the AAA fragments. The DHr variable is dependent and correlated with Dmax. There was no correlation between the other geometric indices and the biomechanical parameters of the AAA wall. The asymmetries did not globally influence the biomechanics of AAA wall; however, they may influence regionally. Larger AAAs were stronger than smaller ones. Therefore, such findings may point toward Dmax is still the main geometric parameter, which influences the anterior wall, and possibly globally in the AAA.

Editor's Choice - In Hospital and Long Term Outcomes After Repair of Subclavian and Axillary Artery Injuries.

OBJECTIVE: To evaluate the in hospital and long term outcomes after open or endovascular repair of subclavian and axillary artery injuries. METHODS: This was a retrospective, single centre study. Data were reviewed from patients with subclavian and or axillary injuries who presented to the authors' centre between January 2009 and December 2022. Outcome data included complications, death, amputations, and re-interventions. A p value < .050 was considered to be statistically significant. RESULTS: Over the study period, 62 patients with subclavian or axillary trauma were admitted to the study hospital. Patients were young (median age 32.5 years, range 12 - 53) and most were men (85%); 32 patients experienced blunt trauma, and 30 penetrating trauma. The median injury severity score was 18 (interquartile range [IQR] 9, 34), and 47% of patients had a brachial plexus injury. The arterial injury was occlusion in 62% of patients, and the median ischaemia time was 12.5 hours (IQR 7.13, 24). All patients with subclavian injuries (n = 37) and 13 of 25 patients with an axillary injury underwent endovascular repair (stent graft placement). Open repair was performed in 12 patients with axillary injury (axillobrachial bypass in seven patients). At hospital discharge, the amputation free survival rate was 82% vs. 92% (p = .67), the mortality rate was 10% vs. 8% (p = 1.0), and the amputation rate was 10% vs. 0 (p = .57) for endovascular and open repair, respectively. The mean follow up time was 4.1 ± 3.5 years. After the seven year follow up, the stent primary patency was 42%. No re-interventions or amputations were performed after hospital discharge. Disability was related to fractures and soft tissue and brachial plexus injuries. CONCLUSION: Endovascular treatment was preferred for patients with subclavian artery injuries. Open repair was preferred for patients with penetrating axillary injuries. In hospital and long term complications were related to fractures and soft tissue and brachial plexus injuries, rather than the treatment of arterial injuries. Measures are needed to reduce ischaemia time and improve brachial plexus injury repair.

The Use of a Low-Fidelity Simulator to Improve Vascular Anastomosis Skills of Residents during the COVID-19 Pandemic.

BACKGROUND: To evaluate a workshop using a low-fidelity simulator for training vascular surgery residents in vascular anastomosis during the COVID-19 pandemic. DESIGN: Prospective, controlled, single-center. METHODS: Vascular surgery residents at the São Paulo University Medical School were enrolled in the COVID Group (five post graduation year 3 residents) or Control Group (five PGY-4 residents). The COVID Group was trained via a vascular anastomosis workshop. The residents were evaluated using Objective Structured Assessment of Technical Skills (OSATS), Final Product Analysis and time to perform the procedure. The number of anastomoses performed by the residents were calculated. Data were subjected to statistical analysis, and P < 0.05 was considered significant. RESULTS: There was a significant reduction in the number of vascular anastomoses performed by the residents between the COVID group and the control group (mean 22.6 ± 7.76 vs. 35.2 ± 3.9, P = 0.01, Student's t-test). Before the workshop, 80% of the residents from the COVID group failed to perform a vascular anastomosis on the simulator. During the workshop, there was improvement in the Objective Structured Assessment of Technical Skills (OSATS) score (initial: 16.5, interquartile range (IQR) 0, under supervision: 25, IQR 5, and at the end of the workshop: 26.5, IQR 2.5; P = 0.049, Friedman's test) and in the Final Product Analysis (initial: 14.5, IQR 6, under supervision: 26.5, IQR 4.625, end of the workshop: 27, IQR 4, P = 0.049, Friedman's test). Time was not significantly different (initial: 35.6, IQR 2.77; under supervision: 25.8 min, IQR 4.53; P = 0.07, Friedman's test). The residents' technical scores were stable 6 months after the training, and there was no difference between their final scores and those of the control group. The residents from the COVID Group reported an improvement in their knowledge, technical skills and confidence after the workshop. CONCLUSIONS: A workshop using a low-fidelity simulator improved vascular surgery residents' skills and confidence in vascular anastomosis during the pandemic year, when they performed fewer surgical procedures.

Natural History of Splanchnic Artery Aneurysms.

INTRODUCTION: Splanchnic artery aneurysms (SAAs) represent a rare and potential life-threatening disease with a documented incidence of 0.1-2.0%. The risk of rupture and the diameter to recommend surgery are still controversial. The purpose of this study was to review surveillance computed tomography scans (CTs) at a high-volume institution in order to better define the natural history of the SAA. METHODS: Between January 2000 and February 2019, all SAAs patients in follow-up at a single center institution were selected for analysis. CTs from patients managed nonoperatively and CTs before surgery from patients submitted to surgery were studied. The first CTs were used to determine aneurysm size, morphology, and anatomic characteristics, and the last CTs performed during nonoperative follow-up were used to compare the diameter with the previous CTs. Primary endpoint included growth rate for all SAAs location, and secondary endpoint included the clinical or anatomical characteristic associated with a faster growth rate. RESULTS: In total, 116 consecutive patients were identified with SAAs and 74 patients with 87 SAAs who had at least 2 CTs during follow-up were analyzed. From those 74 patients, 12 were submitted to surgery and only their preoperative CTs were analyzed. The SAAs' locations were: splenic (55.4%), hepatic (12.2%), superior mesenteric artery (17.6%), celiac trunk (27.0%), gastric and gastroepiploic arteries (1.4%), pancreaticoduodenal and gastroduodenal arteries (4.1%). The median follow-up for all patients was 46.7 months (±35.3), and the median of growth for all aneurysms was 0.63 mm/year (±2.19). Only the splenic aneurysms presented growth with statistic significance of 1.08 mm per/year (±1.99) (P < 0.001). Only portal hypertension showed statistically significance to splenic aneurysm growth (P = 0.002). Multivariate analysis for variables associated with splenic aneurysm growth ≥1 mm/year showed that portal hypertension was the only variable with statistical significance (P < 0.01, IC 95% 2.0-186.9, ß = 19.5). CONCLUSIONS: Although longer-term follow-up and larger sample size are needed to better understand the natural history of SAAs, the majority of SAAs tends to remain stable in size through follow-up. Portal hypertension was the only risk factor found for true splenic aneurysm growth, and so those patients must have a closer follow-up.

Left Common Carotid Artery Biomechanical Properties in Individuals over 80 years: Women Have Stiffer Vessels.

BACKGROUND: Considering the longevity of the worldwide population, the cardiovascular diseases deserve particular attention, especially the carotid artery disease in the ≥80-year-old population. The stiffness of the common carotid artery, for example, has been showed in numerous clinical studies as a marker of increased risk of stroke, dementia, and depression. Besides, with the emergence of new surgical techniques such as the transcarotid artery revascularization that uses the common carotid artery as a workstation, the biomechanical and histological features of this vessel, more than ever, must be detailed. METHODS: Left common carotid artery fragments from 9 cadaver donors (≥80 years old) were evaluated. Biomechanical (failure stress, tension, and strain) and histological (percentage of collagen and elastic fibers) features of these samples were analyzed with special focus on gender differences. RESULTS: Statistically significant differences in biomechanical and histological features between the genders were observed. The percentage of collagen fiber in intima (P = 0.008) and media (P = 0.041) layers was significantly lower in men than in women. A higher elasticity (failure strain) of the specimens in male gender was also observed (P = 0.025). No significant difference was observed in the layers thickness between the genders regardless which part of the arterial wall was considered. CONCLUSIONS: These biomechanical and histological findings could be the responsible for the higher left common carotid artery stiffness observed among ≥80-year-old women when compared with men in numerous clinical studies in literature.