Echocardiographic evaluation of pulmonary embolism and its response to therapeutic interventions.

Imaging and Doppler echocardiography permits assessment of right ventricular size and systolic function and of pulmonary arterial pressures, and it may facilitate detection of thromboemboli within the heart or pulmonary artery. In patients with acute pulmonary embolism of sufficient severity to appreciably increase right ventricular afterload, the right ventricle becomes dilated and hypokinetic. Tricuspid regurgitation is generally apparent, but in the absence of preexisting pulmonary arterial or left heart pathology, the regurgitant flow velocity suggests only mild to mild-moderate elevation of pulmonary arterial systolic pressure. The absence of a greater degree of pulmonary hypertension reflects the inability of the previously normal, nonhypertrophied right ventricle to generate a mean pulmonary arterial pressure in excess of about 40 mm Hg. The echocardiographic abnormalities resolve during recovery from pulmonary embolism. Currently being investigated is the question of whether right heart abnormalities resolve more rapidly with thrombolytic therapy than with heparin therapy alone.