Doppler echocardiographic assessment of changes in pulmonary artery pressure associated with vasodilating therapy in patients with congestive heart failure. Transpulmonic pressure gradient and pulmonary artery pressures can be estimated from the Doppler pulmonary regurgitant flow velocities by applying the simplified Bernoulli equation. In this study, continuous-wave Doppler echocardiography was used to assess changes in pulmonary regurgitant flow velocities associated with administration of vasodilators in 10 patients with congestive heart failure. M-Mode echocardiographic parameters such as left ventricular end-systolic and end-diastolic dimension and fractional shortening did not change with administration of vasodilators. Pulmonary regurgitant flow velocity at end diastole decreased from 1.9 +/- 0.6 to 1.3 +/- 0.3 m/sec (p less than 0.01), and Doppler-estimated transpulmonic pressure gradient at end diastole decreased from 16 +/- 11 to 8 +/- 4 mm Hg (p less than 0.01). Doppler-estimated transpulmonic pressure gradient at end diastole was compared with catheterization-determined pulmonary arterial end-diastolic pressure before and after administration of vasodilators in three patients, and there was a good agreement between these measurements. Thus noninvasive and sensitive assessment of the effect of vasodilators on pulmonary arterial end-diastolic pressure in patients with congestive heart failure is possible with continuous-wave Doppler echocardiographic measurement of pulmonary regurgitant flow velocities. 