Circulatory adjustments after birth: effects on ventricular septal defect.

The haemodynamic effects and clinical manifestations of congenital heart lesions may be greatly influenced by developmental changes in the circulation. The sequential changes associated with abnormal communications between the systemic and pulmonary circulations are well typified by the effect on ventricular septal defect. The possible influences of ventricular septal defect on the foetal circulation are first presented, and the interrelationship between ventricular septal defect and postnatal adjustments of the circulation are discussed.