A pulsed Doppler echocardiographic method for calculation of pulmonary and systemic flow: accuracy in a canine model with ventricular septal defect.

This study was designed to assess the accuracy of a quantitative, two-dimensional, range-gated, Doppler echocardiographic method for estimating systemic and pulmonary flows by comparing them with simultaneous electromagnetic (EM) flow-meter determinations in an open-chest canine model with a ventricular septal defect, the size of which was varied.With each step-by-step variation in defect size, systemic and pulmonary flows were estimated by the Doppler method and matched to simultaneous pulmonary and aortic EM flow-meter recordings.The Doppler value for systemic blood flow was obtained by measuring the size of the aorta on a two-dimensional echocardio- graphic image and sampling blood flow velocity in the ascending aorta.Because of high flow velocities and spectral broadening on the pulmonary artery Doppler flow curves in the presence of ventricular septal defects, pulmonary blood flow was measured as pulmonary venous return through the mitral valve orifice, with the size of the mitral orifice measured on the short axis by two-dimensional echocardiography and with transflow curves obtained from apical views.For a total of 32 left-to-right shunt magnitudes obtained in 10 dogs, excellent correlations were found between ascending aortic Doppler and EM flow-meter values (r = .91,SEE = 0.1 1), between Doppler mitral valve flow and EM flow-meter main pulmonary artery flow values (r = .93,SEE = 0.32), and between Doppler and EM flow-meter determinations of the ratio of pulmonary to systemic flow (r = .93,SEE = 0.52).Our study demonstrates the accuracy of this two-dimensional echocardiographic Doppler method for measuring pulmonary and systemic flows and their ratios in the presence of ventricular septal defects.Circulation 68, No. 3, 597402, 1983.RECENTLY PUBLISHED STUDIES have demon- strated that estimates of cardiac output by two-dimen- sional echocardiographic Doppler methods are reason- ably accurate in the presence of normal or nearly normal circulatory physiology.' -Other preliminary reports have suggested that even in the presence of small intracardiac shunts, Doppler determinations of systemic and pulmonary flows may also be close to those measured by simultaneous invasive techniques.'The purpose of our study was to assess the accuracy of systemic and pulmonary flow values measured with a quantitative two-dimensional, range-gated, echocar-