The Transition from Fetal to Postnatal Life: Normal and Abnormal Hearts

Abstract

At no other time in life does the human cardiovascular system undergo changes as profound as those changes that occur at birth. The circulation switches from one that is in parallel to one that is in series, systemic afterload increases suddenly, and pulmonary afterload decreases. The fetal shunts - the patent ductus arteriosus (PDA) and the patent foramen ovale (PFO) - close. The infant with a cardiovascular anomaly dependent on the parallel circulation and the fetal shunts will not survive the transition to stable postnatal life without intervention. This chapter will first review the prenatal hemodynamics and flow patterns in the normal and abnormal fetal heart. Second, it will describe the circulatory changes accompanying birth and explain the consequences of the extrauterine life to the neonate with cardiac anomalies.