Evaluation of the responsiveness of elevated pulmonary vascular resistance in children by Doppler echocardiography.

Changes in the Doppler indexes, acceleration time (AcT), right ventricular ejection time (RVET), AcT/RVET ratio and pulmonary artery peak velocity were measured as were changes in pulmonary artery pressure and pulmonary vascular resistance in 21 children with pulmonary hypertension due to a large interventricular communication. In 11 children pulmonary vascular resistance was greater than 4.6 U/m2 (mean 8.6 +/- 1.6), whereas in 10 it was less than 4.5 U/m2 (mean 3.4 +/- 0.2). Although both groups demonstrated acceleration time and AcT/RVET values above normal, there were no significant differences in these values between the groups with high and low pulmonary vascular resistance. With administration of a pulmonary vasodilator pulmonary vascular resistance decreased in 11 responders by greater than 50% of baseline values (from 5.3 +/- 0.7 to 1.6 +/- 0.3 U/m2), whereas in the 10 nonresponders mean pulmonary vascular resistance decreased from 7.0 +/- 1.9 to 4.9 +/- 1.1 U/m2. There was no significant change in the Doppler indexes except for an increase in pulmonary artery peak velocity in the responders from 1.34 +/- 0.07 to 1.66 +/- 0.06 m/s (p less than 0.001). The results indicate that Doppler echocardiography cannot predict either the level of increased pulmonary vascular resistance or the degree of responsiveness sufficiently to obviate the need for cardiac catheterization in patients with interventricular communication and pulmonary hypertension.