Causative & risk factors
Atrial septal defect is caused due to a genetic defect, sometimes combined with environmental influences. These environmental factors include the abuse of alcohol or drugs by the mother. Certain diseases affecting the pregnant mother such as diabetes, rubella etc. increase the babies risk of developing ASD.
In-utero babies normally have an opening between the 2 atria so that the blood can bypass the lungs. This opening closes by the time the baby is born. Persistence of this opening even after birth is termed as atrial septal defect.
Because of this opening in the atrial septum, oxygenated blood from the left atrium backflows; and mixes up with the deoxygenated blood from the right atrium. This blood travels back to the lungs for oxygenation. Thus the lungs have to overwork in order to oxygenate the same blood again. Overworked lungs overwork the heart too and eventually ASD results in pulmonary as well as cardiac problems.
Clinical presentation
Even though atrial septal defect is a congenital condition, the symptoms do not occur until decades.
The patient may experience breathlessness and fatigue, even with moderate exertion. Palpitations can be felt by the patient. The skin may acquire a bluish tinge (cyanosis). Recurrent lung infections are common in patients with ASD.
On examination, the physician can detect a heart murmur. There is obvious swelling in the lower limbs and sometimes the abdomen.
Complications of ASD include strokes, pulmonary hypertension, Eisenmenger syndrome and right-sided heart failure.
Investigations
Before birth of the baby, an ultrasound of the womb can detect an atrial septal defect.
A combination of basic investigations such as a chest X-ray, an electrocardiogram and an echocardiogram of the heart can diagnose an atrial septal defect after the baby is born. Specialized investigations such as a heart MRI and cardiac catheterization are done to assess the severity and functional effects of the atrial septal defect.
Treatment
Small asymptomatic atrial septal defects need not be treated. These will be regularly monitored by the physician.
Surgical correction of ASD is recommended for most children, where the defect does not close by itself. The procedure can be performed via cardiac catheterization or as an open heart surgery. Cardiac catheterization involves closing the defect via a mesh or plug; whereas in an open procedure, the defect is closed by sutures.
Medications such as beta-blockers, anti-platelet agents or anti-coagulants are prescribed to relieve the symptoms produced by an ASD.
Statistics
Atrial septal defect is the third most common type of congenital heart defect, accounting for approximately 7 percent of all congenital heart disorders.
