[Diastolic pulmonary forward flow associated with pulmonary regurgitation demonstrated by Doppler echocardiography]

To demonstrate diastolic pulmonary forward flow, pulsed and continuous wave Doppler echocardiograms were recorded in four patients with postoperative residual pulmonary stenosis and regurgitation (Group I). To clarify the mechanism, we further examined 24 patients with pulmonary regurgitation without diastolic pulmonary forward flow, including three patients with surgical correction of tetralogy of Fallot (Group IIa) and 21 patients with functional pulmonary regurgitation (Group IIb), and compared the peak velocity and pressure half time of pulmonary regurgitation among the three groups. Diastolic pulmonary forward flow was characterized as a flow signal which began after the abrupt cessation of pulmonary regurgitation and continued until the beginning of ejection flow. The onset of the flow coincided with that of premature opening of the pulmonary valve, and was following atrial contraction in one, before atrial contraction in two, and mid-diastolic in one. The velocity of diastolic pulmonary forward flow was increased during inspiration and its maximum velocity was 1.3 m/sec. Simultaneous recording of pressures and continuous wave Doppler echo performed in two patients in Group I showed the equalization of right ventricular and pulmonary artery pressures during the flow. There was no significant difference in the peak velocity of pulmonary regurgitation among the three groups of patients. The mean pressure half time was significantly shortened in patients in Group I (90 +/- 11 msec) compared with those in patients in Group IIa (143 +/- 40 msec, p less than 0.05) and Group IIb (310 +/- 71 msec, p less than 0.001). In conclusion, a diastolic pulmonary forward flow seems to be produced by the rapid equalization of right ventricular and pulmonary artery pressures due to severe pulmonary regurgitation in the face of decreased right ventricular compliance.