Subclavian Pulse Tracings

Background Evaluation of regional aortic elastic properties in humans has been hampered by the need for invasive techniques to access instantaneous aortic pressure, wall thickness, and cross-sectional area or diameter. In this study, a new noninvasive method is presented for quantification of regional aortic elastic properties. Methods and Results Twenty-five patients were studied during transesophageal echocardiographic procedures. Measurements of instantaneous aortic cross-sectional area were obtained with an automated border detection algorithm applied to short-axis transesophageal two-dimensional echocardiographic images of the proximal descending thoracic aorta. Instantaneous aortic wall thickness was derived from combined two-dimensional targeted M-mode end-diastolic wall thickness and instantaneous aortic area measurements. Instantaneous aortic pressures were estimated from calibrated subclavian pulse tracings recorded simultaneously. Data were digitized to generate aortic area-pressure loops. Regional aortic mechanical properties were quantified in terms of compliance per unit length (C is the slope of the area-pressure