Congenital heart disease can be broadly classified into cyanotic and acyanotic. Acyanotic congenital heart disease can be further subdivided into left to right shunts, obstructive lesions and a miscellaneous group. Cyanotic congenital heart disease can be classified into those with decreased pulmonary blood flow and those with increased pulmonary blood flow.
Left to right shunts include atrial septal defect, ventricular septal defect, patent ductus arteriosus and aortopulmonary window. One person can have more than one of these shunts. Large left right shunts can induce the development of pulmonary hypertension and lead to reversal of shunt later. Thus they develop cyanosis and are called Eisenmenger syndrome. Left to right shunts are subdivided into pre tricuspid and post tricuspid shunt. Pre tricuspid shunts are atrial septal defects and partial anomalous pulmonary venous drainage, though the latter is often associated with atrial septal defect. Post tricuspid shunts are ventricular septal defect, patent ductus arteriosus and aortopulmonary window. Of these aortopulmonary window has the highest chance of early development of pulmonary hypertension and Eisenmenger reaction.
Obstructive lesions include pulmonary stenosis, aortic stenosis and coarctation of aorta.
Miscellaneous group of acyanotic lesions include anomalous origin of left coronary artery from pulmonary artery (ALCAPA), congenital mitral stenosis, congenital mitral regurgitation etc.
Cyanotic congenital heart disease with reduced pulmonary blood flow are those with tetralogy of Fallot like physiology. Basically all these conditions have reduced pulmonary blood flow due to subpulmonic obstruction. Other conditions in this group are double outlet ventricle with ventricular septal defect and pulmonary stenosis, transposition of great arteries with ventricular septal defect and pulmonary stenosis, and single ventricle with pulmonary stenosis.
Cyanotic congenital heart disease with increased pulmonary blood flow include transposition of great arteries without pulmonary stenosis, double outlet right ventricle without pulmonary stenosis, truncus arteriosus, and single ventricle without pulmonary stenosis. These cases rapidly develop pulmonary hypertension.
Congenital heart disease occur at a rate of 0.8 per thousand live birth. They are more common in premature babies, with most of them having a patent ductus arteriosus. In mature babies the commonest congenital heart disease is ventricular septal defect if bicuspid aortic valve is excluded. Maternal diseases like rubella can contribute to congenital heart disease. Peripheral pulmonary stenosis and patent ductus arteriosus are associated with congenital rubella syndrome. Ebstein’s anomaly of the tricuspid valve has been described in infants of mothers who receive lithium therapy during pregnancy.