Congenital heart defects occur in approximately 1% of live births.
The VSD is the most common congenital heart defect (34%) (Table 4.12). Atrial septal defect (ASD) is second in frequency (15%) and patent ductus arteriosus is third (9%); thus, the common left to right shunts comprise 58% of the total.
The common right to left shunts comprise 12% of defects, while the common obstructive defects such as pulmonary artery stenosis, aortic stenosis, and coarctation of the aorta comprise 18%.
All the rest of the less common and complex cardiac defects make up the remaining 12%.