CAUSATION

INCIDENCE OF CONGENITAL HEART DISEASES

PATENT DUCTUS ARTERIOSUS (PDA)

No underlying cause id found in most of the cases of congenital heart disease. However, the following factors are possibly responsible for it.

1. Maternal Rubella, maternal lupus and other viral infections in the first 2-3 months of pregnancy. These may result in PDA and peripheral type of Pulmonary stenosis.
2. Genetic defects <5% like mongolism, Turner’s syndrome, Marfan’s syndrome and others.
3. Hypercalcaemia and excessive Vitamin D intake by mother.
4. Nutritional and vitamin deficiencies of mother during pregnancy.
5. Gestation at high altitude possibly due to associated anoxia.
6. Sex: Both sexes are affected but in males coarctation of aorta and some other anomalies are common, while in females patent ductus arteriosus , artrial septal defect, etc. are common.
7. Drugs and agents: Some drugs particularly thalidomide taken within 5^th to 8^th weeks of pregnancy, ionising radiation, progesterone – oestrogen preparations, lithium, hypoglycaemic agents.
8. Heredity: Autosomal recessive or autosomal dominance.
9. Pregnancy at older age.
10. Foetal alcohol syndrome.

CLASSIFICATION: PATENT DUCTUS ARTERIOSUS (PDA)

Congenital heart diseases may be classified into the following three groups.

PATENT DUCTUS ARTERIOSUS (PDA)

1. Communications between systemic and pulmonary circulation.
2. Predominant left to right shunt, e.g., atrial septal defect, ventricular septal defect, patent ductus arteriosus, etc.
3. Predominant right to left shunt, e.g., ASD, VSD and PDA with shunt reversal (Eisenmenger’s syndrome), fallot’s tetralogy.
4. Obstructive lesions, atresia or chamber atresia, e.g., coarctation of aorta, pulmonary stenosis, aortic stenosis, pulmonary atresia, right ventricular hypoplastic syndromes.
   

   PATENT DUCTUS ARTERIOSUS (PDA)

5. Displacement of chambers, vessels or valves. These may be associated with (1) or (2), e.g. dextracardia, right-sided aorta, taussig-bing syndrome, anomalous pulmonary venous drainage, etc.

PATENT DUCTUS ARTERIOSUS (PDA)

Ductus arteriosus in normally present in the intrauterine life but closes soon after birth. When it does not close, this condition develops. Maternal Rubella may account for the incidence of PDA in many cases, Here blood from the aorta is shunted to the pulmonary artery both during systole and diastole.Thus volume overload is imposed on the left ventricle as it pumps blood blood both into systemic and pulmonary circulation. Significant haemodynanic changes are not seen in small shunt but there is a threat to endocarditis. Moderate shunt will lead to volume load on the left atrium and ventricle with left ventricular dilatation and atrial fibrillation.

PATENT DUCTUS ARTERIOSUS (PDA)