Expansion rate of thoracic aortic aneurysms and influencing factors.

The risk of rupture of an aortic aneurysm increases with size and rapid expansion rate. We studied the expansion rate of thoracic aortic aneurysms and the factors influencing expansion rate, and compared the results with those of abdominal aortic aneurysms. Forty thoracic aortic aneurysms and 25 abdominal aortic aneurysms were serially examined with enhanced and nonenhanced computed tomography. The mean expansion rate of thoracic aortic aneurysms was 1.3 +/- 1.2 mm/yr and was significantly lower than 3.9 +/- 3.2 mm/yr of abdominal aortic aneurysms. The factors increasing expansion rate of thoracic aortic aneurysms were initial size of aneurysms, diastolic blood pressure, and presence of renal failure by univariate analysis. Multivariate analysis concerning the entire aortic aneurysms also revealed that the large size of the aneurysm and the presence of the aortic aneurysm in the abdomen increased expansion rate of aneurysms.