[Hemodynamic determinants of late systolic reversed flow in the main pulmonary artery in pulmonary hypertension: a pulsed Doppler echocardiographic study].

Pulsed Doppler echocardiograms of the main pulmonary artery were evaluated in 46 cases including 23 cases with valvular heart disease, 13 with an intracardiac shunt, two with severe right ventricular failure and low cardiac output state, and eight healthy normals. In each Doppler echocardiogram the sample volume was placed at well defined nine locations within the main pulmonary artery. Among 23 cases with valvular heart disease, 10 cases with pulmonary hypertension showed a late systolic reversed flow ("rebound" pattern : type B) in all nine sample volumes examined. This pattern was neither detected in any cases with normal pulmonary arterial pressure, cases with an intracardiac shunt, cases with low cardiac output state, nor healthy normals. A comparative study of 10 cases with "rebound" pattern (type B) and 13 cases without it disclosed that the former had a significantly increased pulmonary arterial pressure (30.9 + 15.1 mmHg vs 17.8 +/- 9.0 mmHg, p less than 0.001), an increased total pulmonary resistance (789 +/- 496 dynes X cm X sec-5 vs 285 +/- 170 dynes X cm X sec-5, p less than 0.001) and a decreased pulmonary arterial compliance expressed as stroke volume divided by pulmonary arterial pulse pressure (1.75 +/- 0.94 ml/mmHg vs 3.80 +/- 1.65 ml/mmHg, p less than 0.01). Mean acceleration of the pulmonary ejection expressed as peak flow velocity divided by acceleration period was also significantly larger in cases with "rebound" pattern (type B) than in cases with "normal" pattern (938 + 255 cm X sec2 vs 675 +/- 160 cm X sec2, p less than 0.01). In conclusion, "rebound" pattern (type B) in pulmonary hypertension is not simple swirl formation, but a totally reversed late systolic flow in the main pulmonary artery, which is caused by sudden interruption of the distal run-off due to markedly elevated total pulmonary resistance under normal right ventricular ejection.