Introduction to congenital heart disease

Congenital heart disease

Introduction to congenital heart disease

Definition

Developmental abnormalities of the heart.

Prevalence

Up to 1% of live born infants are affected by some form of congenital heart disease.

Age

Congenital.

Sex

M > F

Aetiology

The aetiology of most congenital heart disease is un-known, and associations are as follows:

Genetic factors: Down, Turner, Marfan syndromes. Environmental factors: Teratogenic effects of drugs

and alcohol.

Maternal infections such as rubella, toxoplasmosis.

Pathophysiology

Normally in postnatal life the right ventricle pumps de-oxygenated blood to lungs and the left ventricle pumps oxygenated blood at systemic blood pressure to the aorta, with each ventricle morphologically adapted for its task. The pulmonary circulation normally has low resistance.

Congenital heart lesions can be considered according to one or more of

·        Abnormal shunting of blood back to the lungs (left to right). Blood from the left side of the heart is returned to the lungs instead of going to the systemic circulation.

·        Abnormal shunting of blood from the lungs (right to left) in which deoxygenated blood bypasses the lungs and enters the systemic circulation.

·        Narrowed cardiac outflow channels or valves.

·        Abnormal connections or positions of chambers.

Clinically lesions can be divided into two categories:

·        Acyanotic heart disease, which include the left to right shunts (atrial septal defects, ventricular septal defects and persistent ductus arteriosus) and obstructive lesions (aortic stenosis, right ventricular outflow tract obstruction, coarctation of the aorta and mitral stenosis).

·        Cyanotic heart disease including tetralogy of Fallot and transposition of the great arteries.