CARDIOVASCULAR FLOW DYNAMICS--IN VIVO STUDIES

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This project has continued studies of intracardiac flow dynamics using newly developing non invasive ultrasonic imaging techniques for quantifying pathophysiologic hemodynamic abnormalities. Based upon hydrodynamic principles (jet flux theory, momentum continuity preservation, centerline acceleration, proximal flow convergence and turbulent/viscous interactions), temporal and spatial quantitation of flow events is possible. In the clinical management of cardiac dysfunction, accurate evaluation of the severity of hemodynamic abnormalities is of major importance. Doppler echocardiographic techniques have enhanced non invasive assessments. However, there have been, heretofore, few studies related to the clinical applicability of these techniques using strictly quantified reference standards for validation. To that end, the current year's efforts have extended previous years' studies to show the following: 1) A new Doppler flow calculation method which semiautomatically integrates digital spatial and temporal color flow velocity data has been validated for determining pulmonary arterial and aortic flows and for calculating intracardiac shunt flows. 2) Real-time three-dimensional imaging permitted determination of ventricular volumes and thus the calculation of stroke volumes and shunt magnitudes. 3) Using real-time three-dimensional imaging, unique en face views were developed for directly imaging the size and shape of atrial septal defects. 4) The color Doppler imaged vena contracta width was shown to correlate closely with the severity of aortic and mitral regurgitation. Non invasive imaging methods for structure and flow, thus validated in vivo, provide reliable information about the severity of cardiac valvular regurgitation to aid patient clinical management.