Ligation of the PDA in premature infants is well tolerated when there is no underlying pulmonary or CNS hemorrhage or bronchopulmonary dysplasia. Many premature infants require interruption of the large left-to-right shunting PDA in the management of intractable cardiorespiratory failure. Prompt interruption of large left-to-right shunts through the PDA in mechanically ventilated premature infants with severe RDS may prevent the development of severe bronchopulmonary dysplasia, a major cause of mortality among these infants.