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Congenital heart defects

  • By Team TDO

CHDs arise if changes from fetal to extra-uterine circulation are not properly complete. During fetal development, the heart develops as a single tube and later divides into two separate circulations - systemic and pulmonary circulations. Failure of separation leads to atrial and ventricular septal defects. Atrial septal defects occur at the site of foramen ovale. Failure of alignment of great vessels with ventricles leads to tetralogy of Fallot, transposition of great vessels, and truncus arteriosus. Patent ductus arteriosus occurs if ductus arteriosus fails to close after birth.

Some diseases, certain medications used by pregnant mothers, environmental factors, etc., may lead to CHDs in the newborn child. Diseases like diabetes, rubella (German measles) may cause heart defects in fetus. Medications like thalidomide, isotretinoin (used for acne), anti-seizure drugs like phenytoin, valproate (used in epilepsy) if administered during pregnancy, may cause defects in heart in the newborn. Certain lifestyle factors like smoking and alcoholism may contribute towards development of heart defects.

Atrial septal defect (ASD)

ASD is the commonest CHD. It may be located at two sites. One involves fossa ovalis and other involves lower portion of the septum. Most children are free of symptoms for many years and defect is detected during routine clinical examination. However, children with ASD may present with breathlessness, recurrent chest infection, or heart failure. To confirm the diagnosis, chest x-ray, ECG, and echocardiography are done. ASD is treated with surgical closure of the defect. Closure can also be achieved by cardiac catheterisation using an implantable device.

Ventricular septal defect (VSD)

VSD occurs due to incomplete separation of the ventricles. It results in communication between left and right ventricle. Most common site of VSD is the junction of the membranous and muscular portions. The doctor clinically diagnoses VSD by auscultation of pansystolic murmur, an abnormal heart sound. The children may have breathlessness on exertion, heart failure, growth retardation, and recurrent chest infection. Chest x-ray, ECG, and echocardiography are also done to confirm the diagnosis. Small defect requires no treatment; only some steps are required to prevent chest infections. Larger defects require surgical closure.

Patent ductus arteriosus (PDA)

PDA is a communication between pulmonary artery and aortic arch. It occurs due to failure of fetal ductus arteriosus to close after birth. PDA may be present in pre-term infants. PDA increases risk of heart failure. Initially it is treated with diuretics and digitalis. Surgical correction is required for children not responding to medical management or with an absence of spontaneous closure.

Truncus arteriosus

It is a rare CHD characterized by single great vessel arising from heart and contribute to form coronary, systemic, and pulmonary arteries. Oxygenated and deoxygenated blood is ejected into the common great vessel. Both systemic and pulmonary circulations receive mixed venous blood from both ventricles. Surgery is advocated during the first few weeks of life.

Tetralogy of Fallot (ToF)

ToF is characterized by right ventricular outflow obstruction, ventricular septal defect, right ventricular hypertrophy and overriding of aorta. ToF is characterized by cyanosis, often after feeding or crying, and breathlessness. The diagnosis is confirmed by chest x-ray, ECG, and echocardiography. The definitive management is surgical correction of all defects. Surgical corrections may be undertaken in a step wise manner.

Transposition of great vessels

In this defect, the aorta arises from right ventricle and the pulmonary artery arises from left ventricle. Blood flows from right atrium to right ventricle and deoxygenated blood is supplied to the body via aorta. On the other hand, blood flows from left atrium to left ventricle and oxygenated blood is carried to the lungs though pulmonary artery. Surgery is performed within first two weeks of life.

CHDs are frequent causes of death and disability. They are also associated with personal distress and social costs. Although great advances have been made in the diagnosis and treatment of these defects. The pregnant mother should be appropriately screened during their pregnancy to identify any possible risk of CHD in the fetus.