Two methods of measuring stroke volume and cardiac output with pulsed Doppler twodimensional echocardiography were developed and validated against the thermodilution technique in 39 patients, 33 of which were in an intensive care unit. With the use of the apical four-chamber view, a mitral inflow method combined the velocity of left ventricular inflow at the mitral anulus with the crosssectional area of the anulus calculated from its diameter at middiastole (area = z r2). From the apical five-chamber view a left ventricular outflow method combined the velocity of left ventricular outflow with the cross-sectional area of the aortic anulus calculated from its diameter during early systole (parastemal long-axis view). Measurements with the mitral inflow and left ventricular outflow methods were obtained in 35 of 39 (90%) and 39 of 39 (100%) patients, respectively. Validation of the mitral method excluded patients with mitral regurgitation (n = 11) and validation of the left ventricular outflow method excluded those with aortic regurgitation (n = 4). Good correlations were observed between thermodilution and Doppler measurements of stroke volume and cardiac output for both the mitral anulus method (R = .96 and .87, respectively) and the left ventricular outflow method (R = .95 and .91, respectively). The results of the two methods correlated well with each other in patients without regurgitant valve lesions. A greater interobserver variability was observed with the mitral anulus method, which was related solely to greater variability in measuring the annular diameter. In patients with mitral regurgitation, left ventricular inflow volume was always greater than left ventricular outflow stroke volume while the inverse was true in those with aortic regurgitation. Thus, stroke volume and cardiac output can be accurately measured from the cardiac apex with mitral inflow or left ventricular outflow methods when applicable. Comparison of volumes obtained with these two methods may prove valuable in quantitating the severity of mitral or aortic regurgitation. Circulation 70, No. 3, 425-431, 1984. RECENT technological developments have made possible the application of Doppler echocardiography to the measurement of stroke volume and cardiac output. Methods previously validated consist of measuring ascending aortic flow from the suprasternal window or pulmonary arterial flow from the parasternal window.1-' These methods work on the premise that the velocity of blood flow determined from the Doppler

In this autopsy series, HCM represented a common cause of sudden death in young and previously undiagnosed African American male athletes, in sharp contrast with the infrequent clinical identification of HCM in a hospital-based population (i.e., by seven-fold). This discrepancy suggests that many HCM cases go unrecognized in the African American community, underscoring the need for enhanced clinical recognition of HCM to create the opportunity for preventive measures to be employed in high-risk patients with this complex disease.

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In patients with low to moderate risk of cardiac disease, DSE performed as part of an evaluation for liver transplantation is a poor predictor of major perioperative events.

Doppler echocardiographic indices of left ventricular filling may aid in distinguishing between pronounced physiological hypertrophy due to athletic training and pathological hypertrophy associated with hypertrophic cardiomyopathy.