Diastolic forward blood flow in the pulmonary artery detected by Doppler echocardiography.

The etiology of diastolic motion of the pulmonary valve seen on the M-mode echocardiogram has been the subject of much debate. To further investigate diastolic events in the pulmonary artery, the patterns of diastolic pulmonary artery blood flow velocity were studied using pulsed Doppler echocardiography in patients with a normal heart. Two diastolic waveforms were found, one in early diastole related to passive filling of the right ventricle and one in late diastole related to atrial contraction. These waveforms were also related to the two recognized phases of diastolic pulmonary valve motion detected by M-mode echocardiography. The presence of biphasic diastolic blood flow in the pulmonary artery was confirmed by electromagnetic flow velocimetry in four additional patients with various cardiac diseases and normal right heart pressures. It is concluded that both atrial contraction and passive right ventricular filling produce blood flow in the pulmonary artery.