Cardiovascular Flow Dynamics - IN Vivo Imaging Studies

Jones, M.

Abstract

This project emphasizes studies using newly emerging robust non invasive ultrasonic imaging technologies for quantifying structural and functional cardiovascular pathology. Using hydrodynamic principles, temporal and spatial aspects of cardiac structural abnormalities and pathophysiologic flow events are described and their quantification validated. In the clinical management of cardiac dysfunction, quantitativelyaccurate assessment is of major importance for diagnosis, prognosis and therapy. Non invasive assessment is, in addition, economically desirable. To these ends, the current year's efforts have extended previous years' studies to include: 1) In ex vivo animal studies, a strong correlation was validated between actual left ventricular volumes and those calculated with real-time, three-dimensional echocardiography. 2) In vivo, apically rotated 6 plane measurement methods with real-time, three-dimensional echocardiography correlated well with reference standards for calculating left ventricular volumes when compared with electromagnetic flow probe methods and magnetic resonance imaging. 3) Real-time, three-dimensional echocardiography was also validated for quantifying left ventricular volumes in the presence of left ventricular asymmetry, i.e. in the presence of left ventricular aneurysms. 4) Using real-time, three-dimensional color Doppler with its unique c-plane, which is perpendicular to flow, the cross-sectional spatial velocity distributions in the left ventricular outflow tract were imaged. 5) Peak flow rates were obtained by spatially integrating the velocity data from the cross-sectional color images of the left ventricular outflow tract. Thus, estimations of peak flow rates were possible without any assumptions about flow velocity geometric distribution. 6) By applying a temporal averaging factor to correct for underestimation, there was an excellent agreement between reference flow rate by electromagnetic flow meter and real-time, three-dimensional color Doppler echocardiography. These studies have been published or are in press. On-going studies using three-dimensional structural imaging and three-dimensional Doppler flow imaging use animal models of chronic aortic and mitral regurgitation.