This independent study consists of:

1. General notes on congenital heart disease

2. Three case studies

3. Three case discussions with links to WebPath.

CONGENITAL HEART DISEASE

Incidence and Clinical features:

• Malformations of the heart are the commonest of all congenital anomalies

• Ventricular septal defect is the commonest congenital heart disease

• Clinical features include: Failure to thrive, cyanosis, clubbing, infective endocarditis, polycythemia (® cerebral thrombosis), thromboemboli

Pathogenesis of congenital heart disease: Majority are due to idiopathic developmental errors however there is an increased incidence in association with some factors

i) Environmental Factors:

• Intra-uterine infections e.g. Rubella during first trimester

• Radiation

• Metabolic disorders: Maternal diabetes mellitus

• Drugs: alcohol abuse, smoking, thalidomide, phenytoin

• Geographical: High altitude

 

ii) Genetic Factors: Chromosomal abnormalities account for < 5% of all cardiac anomalies e.g. Down’s syndrome with atrial septal defects

A. Left to Right shunts with Late Cyanosis

• These defects are initially acyanotic as they allow oxygenated blood from the Lt®Rt side of the heart

• Eventually the  ­ volume load and pressures in the Right side of the heart  ® thickening of pulmonary arteries with ­ pulmonary vascular resistance (pulmonary hypertension) leading to Right ventricle hypertrophy. When the pressures in the Rt ventricle exceed those in the Lt ventricle, reverse shunting will occur (Eisenmenger’s complex) with de-oxygenated blood entering into the systemic circulation and late onset cyanosis

Ventricular Septal Defect:

• Defect in the interventricular septum

• Spontaneous closure can occur with small defects

 

Atrial Septal Defect:

• Defect in the interatrial septum

 

Patent Ductus Arteriosus:

• Normally patent in the fetus. Functional closure occurs within 1-2 days of birth

• May remain patent at high altitude or with hypoxemia

B. Right to Left Shunts with Early Cyanosis

Poorly oxygenated blood from the Right side of the heart bypass the lungs and enters the systemic circulation leading to early cyanosis

 

Tetralogy of Fallot:

• Commonest type of cyanotic congenital heart disease

• Ventricular septal defect + overriding aorta + Pulmonary stenosis + Rt ventricular hypertrophy

 

Transposition of the great arteries:

• The Rt ventricle pumps into the aorta and the Lt ventricle into the pulmonary artery. Survival is only possible with an associated atrial / ventricular septal defect or ductus arteriosus

C. Obstructive Non-Cyanotic Anomalies

Coarctation of the aorta:

• Upper extremity hypertension, collaterals ® rib notching

• Heart failure, infective aortitis, proximal dissection / rupture