Persistent pulmonary hypertension of the newborn: echocardiographic assessment

Twenty seven newborn infants with persistent hypoxemia in the first 3 days after birth were enrolled for hemodynamic assessment using echocardiography. Measurements included pulmonary arterial pressure (peak velocity of tricuspid regurgitation (TR), patent ductus arteriosus (PDA) flow pattern, interatrial shunting flow pattern and pulmonary flow velocity ratio (the time to peak velocity/right ventricle ejection time ratio (TPV/RVET)) and left ventricular ejection fraction. The estimated systolic pulmonary arterial pressure and the systemic arterial pressure determined via an indwelling arterial line were recorded at the time of echocardiographic examination, and pulmonary arterial pressure/systemic arterial pressure was calculated. Nineteen infants (70.4%) had a TR sufficient to estimate systolic pulmonary arterial pressure. The median value of pulmonary arterial pressure/systemic arterial pressure was 1.02 (range, 0.68 to 1.78). Twenty two infants (81.5%) had a PDA and flow patterns indicating pulmonary arterial pressure above or approaching systemic arterial pressure. All infants had a foramen ovale and flow patterns were bi-directional or pure right-to-left. TPV/RVET had a wide range of values (0.23 to 0.55), and only 44.5% of infants had high pulmonary arterial pressure as reflected by low TPV/RVET ratio. Eleven infants (40.7%) had an ejection fraction below the normal range. Results of 17 survivors were compared with 8 deceased infants (2 infants of birth weight less than 1000 gm were excluded who died of massive pulmonary hemorrhage). There were no significant differences for any parameter of pulmonary arterial pressure, but ejection fraction was significantly lower in deceased infants. This study has demonstrated that it is possible to evaluate pulmonary arterial pressure noninvasively by using echocardiography in most newborn infants with clinical evidence of persistent pulmonary hypertension of the newborn (PPHN). Ejection fraction is an echocardiographic parameter which can significantly predict mortality.