Pulse wave patterns in patent ductus arteriosus.

Pulse wave patterns were analysed in 10 term and 10 preterm infants with patent ductus arteriosus (PDA) and in 2 matched control groups. A non-invasive technique was used to record the pulse waves from the axillary artery. The pulsatile ratio was calculated as the quotient between the amplitude of the incisural notch and the peak of the pulse wave above the end diastolic baseline. The pulsatile ratio was considerably lower in preterm and term infants with PDA compared with the ratio after closure of the ductus and the ratio in control infants. A pulsatile ratio less than 0.50 indicates the presence of a large PDA whereas a ratio over 0.55 is normal. The technique may be used to document and evaluate arterial pulse wave patterns and may be a useful diagnostic tool.