Contrast echocardiography in pulmonary hypertension: observations explaining the early closure of the pulmonic valve.

We studied pulmonary artery flow patterns in 11 patients with pulmonary hypertension and 11 normal volunteers, by means of peripheral intravenous injections of 5% dextrose solution during M-mode echocardiography. Most of the patients had moderate to severe pulmonary hypertension. All normal subjects had antegrade flow throughout systole until just prior to pulmonic valve closure; none of the patients with pulmonary hypertension had continued antegrade flow throughout systole. The seven with early closure of the pulmonic valve showed abnormal retrograde flow of contrast in mid- to late systole; this was never observed in normal subjects. We conclude that early closure of the pulmonic value is seen in patients with early systolic retrograde flow in the pulmonary artery. A hypothesis for the pathogenesis of this flow is presented. Contrast M-mode echocardiography is a valuable new tool for the study of flow characteristics over the pulmonic valve. In patients with poor quality pulmonic valve echograms during systole, retrograde flow during midsystole imaged by contrast echocardiography may substitute for early closure as a sign of pulmonary hypertension.