Effects of assisted ventilation on echocardiographic findings in two infants with patent ductus arteriosus.

Echocardiography is a useful means of determining whether or not to ligate the patent ductus arteriosus (PDA) in premature infants with respiratory distress syndrome and PDA. The magnitude of the left-to-right ductal shunt can be gauged by measuring the diameter of the left atrium (LA) and aortic root (AO) echocardiographically and by determining the LA/AO ratio. An increase in this ratio during weaning from assisted ventilation is an indication for ligation of the PDA. We recently used this criterion in treating 2 infants with respiratory distress syndrome and PDA.