Aortic wall tension as a predictive factor for abdominal aortic aneurysm rupture: improving the selection of patients for abdominal aortic aneurysm repair.

Aortic wall tension was determined in 40 patients to assess its predictive value in abdominal aortic aneurysm (AAA) rupture. A 3-year retrospective analysis of 243 patients with ruptured AAAs and 45 patients with intact AAAs was conducted. The 288 patient sample was limited to the 40 patients with an abdominal CT scan investigation. Aortic wall tension was calculated using blood pressure data and measurements from computerized tomographic (CT) images of 26 patients with intact AAAs and 14 patients with ruptured AAAs in accordance with LaPlace's Law for wall tension: P x R/W, where P = mean arterial pressure (MAP), R = radius of the vessel, and W = wall thickness of the vessel. The wall tension was approximated with the more readily accessible patient parameters of AAA diameter, MAP, height, and weight. This approximation was termed the body mass index (BMI)-pressure approximation for tension (BPAT), which is AAA diameter/BMI x MAP. Data were analyzed using one-sided t-tests, chi-squared tests, and a regression analysis for the relationship between aortic wall tension and the BPAT. AAA wall tension is a significant predictor of pending rupture. BPAT used to approximate the actual tension in the AAA wall is a more sensitive predictor of rupture than aneurysm diameter alone. A prospective study has been initiated to validate these conclusions.