DEFINITIONCongenital heart disease is defined as the structural, functional or positional defect of the heart in isolation or in combination, present from birth, but may manifest at any time after birth or may not manifest at all.
Congenital heart disease remains a problem of major importance particularly for the family physician, who is first in the line of medical professionals, to diagnose and counsel the patients and the family. It is the most common single group of congenital abnormalities accounting for about 30 percent of the total.
INCIDENCE The general reported incidence varies from 8-10 per 1000 live newborn population. There are eight common lesions, which account for 85 percent of all cases. They are:
- ventricular septal defect (VSD)
- patent ductus arteriosus (PDA)
- atrial septal defect (ASD)
- pulmonary valve stenosis
- aortic valve stenosis
- coarctation of the aorta
- Tetralogy of Fallot
- Transposition of great arteries
The remaining 15 percent account for a variety of more rare and complex lesions. Congenital heart disease as a whole, occurs with an equal frequency in males and females but some lesions such as aortic stenosis, coarctation of the aorta are more common in males, while patent ductus arteriosus and atrial septal defects are more common in females. About 13 percent of patients with one heart defect, will have an additional cardiac defect. About 10 to 15 percent of patients with heart defect will have another non-cardiac deformity. The risk of siblings being affected by congenital heart disease is between 2 and 4 percent. So, parents who have had one child with congenital heart disease should, if they wish, be advised by a genetic counselor.
ETIOLOGYNo specific causes are found in most cases of congenital malformations of the heart. In a minority cases, clear-cut single causes, either environmental or genetic, are responsible. No good evidence is available implicating interaction of specific genetic and exogenous factors in the causation of cardiac malformation in man, though experiments on animals suggest such an interaction.
A few families are reported in which defect follows dominant pattern of inheritance, e.g. atrial septal defect, supravalvular aortic stenosis, cardiomyopathy. Recessive autosomal inheritance confined to heart is exceptional.
About 5 percent of
patients with congenital heart disease are associated with some chromosomal abnormalities (Table 1).
Incidence of Congenital Heart Disease with chromosomal abnormalities
A-V canal defect
VSD, PDA, DORV
Coarctation of aorta,
Increased incidence of congenital heart defect has been noted with intrauterine viral infections, maternal drug consumption during first trimester of pregnancy and pregnancy-induced systemic maternal diseases. (Table 2)
Table 2: Incidence of Congenital Heart Disease with environmental factors.
- Rubella: PDA, pulmonary stenosis, VSD, ASD
- Mumps: Endocardial Fibroelastosis
- Phenytoin: Variable
- Vitamin D: Supravalvular aortic stenosis
- Diabetes: Transposition of great arteries
- Systemic Lupus Erythematosus: Congenital Heart Block
The most acceptable theory for the genetic
basis of congenital heart disease is multifactorial hypothesis. It suggests that the abnormalities of genes may not be enough to cause cardiac malformations, but may manifest in presence of above mentioned adverse environmental hazards.
CLASSIFICATION Congenital heart diseases are basically divided into the following groups:
- Structural heart defects
- Functional heart defects, e.g. congenital cardiac arrhythmias
- Positional heart defects, e.g. dextrocardia
Structural heart defects are divided into two main groups:
- Acyanotic defects
- Cyanotic defects
Each group is subdivided according to:
- pulmonary blood flow: increased, decreased or normal
- dominant ventricle - left or right
- pulmonary hypertension - present or absent
The clinical diagnosis of congenital heart is complex when first considered but with sound anatomy and physiologic principles and proper understanding of clinical manifestations, it may become simple. If information is handled with the framework of following figures, the clinical diagnosis becomes simple.
Associated Anomalies with Congenital Heart DiseaseMusculoskeletal- 8.8%
Specific Syndromes- 8.5%
Central Nervous- 6.9%
Recurrence Risks Given One Sibling Who Had a Cardiovascular AnomalyVSD - 3%
PDA - 3%
ASD - 2.5%
TF - 2.5%
PS - 2%
CoA - 2%
AS - 2%
D-TGA - 2%
AV Canal- 2%
EFE - 4%
TA - 1%
Ebstein's Anomaly -1%
Truncus Arteriosus - 1%
PA - 1%
HLHS - 2%