Continuous wave Doppler echocardiography in patent ductus arteriosus

A patent ductus arteriosus (PDA) may be clinically 'silent' in the preterm infant. Two-dimensional and pulsed Doppler echocardiography have increased the sensitivity of noninvasive diagnosis of PDA, but they require considerable skill and expensive equipment. The purpose of this study was to evaluate continuous wave Doppler echocardiography as a rapid and relatively inexpensive method for the detection of PDA in preterm and critically ill infants. Continuous wave Doppler examination was performed 'blindly' with a 2 or 2.5 mHz nonimaging transducer from multiple echocardiographic windows. Standard combined 2-D and pulsed Doppler echocardiographic examination was then performed and compared to the continuous wave Doppler results. Two hundred thirty-three studies were performed in 137 infants (age 1-60 days), weight 0.5-5.6 kg, mean 1.5 kg). PDA was present by 2-D and/or pulsed Doppler in 116 studies (50%). Continuous wave Doppler correctly detected 109 of those 116 (94% sensitivity) with no false positives in the remaining 117 studies (100% specificity). Diagnostic errors occurred in two infants with persistent pulmonary hypertension of the newborn and large PDA with low velocity left to right diastolic ductal flow. The other errors occurred in five very low-birthweight infants with small PDA. Continuous wave Doppler echocardiography is a sensitive and specific tool for the detection of PDA in critically ill and preterm infants. It can be used for early screening for PDA and, following 2-D and pulsed Doppler study to exclude underlying structural heart disease, continuous wave Doppler can be used for serial assessment of ductal patency.