Date of Award

January 2021

Document Type

Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

Cassius I. Ochoa Chaar

Abstract

Rupture of abdominal aortic aneurysms (rAAA) is typically associated with large sac diameter. However, a number of patients experience rupture below the size thresholds for elective AAA repair, referred to in this thesis as “small rAAA”. We aim to investigate the characteristics and outcomes of patients who experience small rAAA in two national databases. The Vascular Quality Initiative (VQI) and American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) targeted files for open AAA repair and endovascular aneurysm repair (EVAR) were reviewed for all surgeries performed for rAAA. Based on the 2018 Society for Vascular Surgery guidelines on operative size thresholds for elective repair, patients with infrarenal aneurysms <5.0cm in women or <5.5cm in men were categorized as “small rAAA,” while those at or above thresholds were considered “large rAAA.” Among the VQI data, patients with iliac aneurysms above the operative threshold of 3.5 cm were considered among the “large rAAA” group. Patient characteristics and perioperative as well as long-term outcomes were compared via univariate regression. Multivariable analysis was used to examine size as an independent risk factor for mortality. Each database was analyzed separately. There were 1,192 rAAA cases in ACS-NSQIP and 3,962 rAAA cases in VQI. The percentage of small rAAA was 12% and was consistent in the 2 databases. In both the VQI and ACS-NSQIP data, patients in the small rAAA group were significantly more likely to be younger, African American, have lower BMI, and had significantly higher rates of hypertension. Small rAAA were more likely to be repaired via EVAR (p<0.01) and less likely to present with hypotension compared to large rAAA. Patients with large rAAA had significantly increased morbidity and mortality compared to small rAAA. However, after adjusting for baseline characteristics, hemodynamic factors, and type of repair, small rAAA was not independently correlated with mortality. Patients presenting with small rAAA represent 12% of all rAAA and are more likely to be African American with hypertension. Patients with small rAAA are less likely to present with hypotension and more likely to be treated with EVAR. There was no statistically significant association of small rAAA with mortality.

Comments

This thesis is restricted to Yale network users only. This thesis is permanently embargoed from public release.

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