Precordial contrast echocardiographic detection of patent ductus arteriosus in small preterm infants

Clinical detection of patent ductus arteriosus (PDA) remains an important and challenging problem in the small preterm infant with respiratory distress. In this study, PDA was diagnosed in 28 small preterms using an improved contrast echocardiographic method. In these infants, the injection of saline into the aorta generated echoes which were imaged at the pulmonary valve. This was accomplished using a conventional M-mode ultrasound transducer applied at the usual precordial position. Contrast echo studies were compared with the degree of ductal patency shown by single film aortography. Ductal patency was detected by contrast echo in 29 of 31 instances of aortographically proven PDA. Indirect echo indices commonly used for detection of PDA (cardiac chamber enlargement) may be limited since factors other than left-to-right shunt can cause cardiac enlargement in distressed small preterms. This direct contrast echo technique is an easily performed, sensitive, qualitative method for confirmation of the diagnosis of PDA in small preterm infants.