RIGHT-VENTRICULAR SIZE IS ACUTELY DECREASED BY INHALED NITRIC-OXIDE IN NEWBORNS WITH PULMONARY-HYPERTENSION

The pressure and volume demands of the right and left ventricles may d ramatically change following selective pulmonary vasodilation in newbo rns with pulmonary hypertension. Thus, ventricular planimetry was perf ormed by two-dimensional echocardiography in 35 newborns with lung dis ease and increased pulmonary vascular resistance who were treated with inhaled nitric oxide to determine the influence of therapy on right a nd left ventricular size and function. The end-diastolic and end-systo lic areas of each ventricle were measured from apical 4-chamber images before, and 30 to 60 minutes after, the onset of 20 parts per million inhaled nitric oxide. Estimates of ventricular function were determin ed by the systolic decrease in ventricular area, (diastolic area - sys tolic area) .100/diastolic area. Heart rate, systemic blood pressure, and left ventricular areas did not change. However, the oxygenation in dex, the proportion of right-to-left ductal shunt (nonrestrictiveductu s arteriosus, n = 22), the systolic pulmonary arterial pressure (close d or restrictive ductus arteriosus, n = 73), and the right ventricular diastolic and systolic areas were decreased after nitric oxide inhala tion. The baseline systolic decrease in left ventricular area was lowe r in a subgroup of patients who developed an increase in left ventricu lar diastolic area following nitric oxide inhalation. Thus, nitric oxi de improves pulmonary hemodynamics and decreases right ventricular siz e in newborns with lung disease and pulmonary hypertension. However, n ewborns may develop an increase in left ventricular size if left ventr icular function is decreased prior to therapy.