Clinical evaluation of atherosclerosis and mechanical properities of the thoracic aorta

To evaluatate the aortic wall atherosclerosis, X-ray CT and ECG gated racionuclide angiography were preformed in 25 subjects. They were classified into 17 normotensive group (N) and 8 hypertensive group (HT). The time-activity curve was generated using radionuclide angiography in the portion of the thoracic aorta. The aortic wall distensibility was expressed as 100ΔV/V_0/PP, where ΔV was difference between maximum and minimum (V_0) counts of the aorta, and PP was pluse pressure. The degree of the aortic wall atherosclerosis was evaluated by X-ray CT. The aortic wall CT-score was calculated from the CT-scores measured within the region of interest of the other margin of the aorta and of the background by X-ray CT. There was a significant correlation between aortic wall CT-score and systolic blood pressure (r＝0.59, p＜0.01) or aortic wall distensibility (r＝-0.74, p＜0.01), but no correlation exsisted between aortic wall CT-score and diastolic blood pressure (r＝0.11, p : NS). The aortic wall distensibility was higher and the aortic wall CT-score was lower in N-group than in HT-group, whereas there was no difference of the radius of the aorta between both groups. These results suggested that the aortic wall atherosclerosis advanced progvessively in hypertensive patients, and systolic blood pressure was a good predictor of the degree of the aortic atherosclerosis.