Abnormal cerebral blood flow patterns in preterm infants with a large patent ductus arteriosus.

To determine whether there are significant alterations in cerebral blood flow patterns in infants with a patent ductus arteriosus and whether these alterations correlate with alterations in aortic blood flow, we performed range-gated pulsed-Doppler examinations of the aorta and cerebral arteries in 20 infants. Ten infants had a PDA and ten control infants did not. We analyzed these flow patterns quantitatively by calculating the pulsatility index (peak systolic frequency minus trough diastolic frequency)/peak systolic frequency. In the ten control infants and in three infants with a small PDA, there was no significant diastolic flow in the descending aorta; flow in the cerebral arteries was antegrade throughout systole and diastole (PI = 0.75 +/- 0.03 for control infants and 0.73 +/- 0.07 for small PDA infants). In seven infants with a large PDA, there was retrograde diastolic flow in the descending aorta. This pattern was not seen after PDA closure. In the cerebral arteries of the seven infants with a large PDA, diastolic flow was retrograde in three and decreased or absent in four, and PI was significantly higher (PI = 0.96 +/- 0.06. P less than 0.001 vs controls). After PDA closure, cerebral diastolic flow was antegrade in all seven infants (PI = 0.74 +/- 0.04). We conclude that a large PDA can cause abnormal flow patterns in the descending aorta and cerebral arteries. These flow patterns may predispose these infants to CNS ischemia or intraventricular hemorrhage.