WHAT IS AN ATRIAL SEPTAL DEFECT (ASD)?
The human heart is a muscle pump working continuously day in and day out to ensure that all the body parts get blood and nutrient required for their functioning. The heart has four chambers, two on top called the ATRIUM and two below the atrium called the VENTRICLES. Inter atrial septum (IAS) is a wall that separates the two atria while the two ventricles are separated by Inter Ventricular Septum (IVS). Because of these two septum the heart functions as two parallel circulation, one on the right that receives blood (oxygen poor) from all over the body, pumps it into the lungs for oxygenation so that the blood (oxygen rich) can then be given to the left side of the heart which then pumps the oxygenated blood to different body parts. These septum prevent the mixing of blood between right and left side of the heart. When inside the mother’s womb, since the lungs are not functional there is a hole present in the IAS (which separates the two atria) that allows blood to flow away from the lungs. After birth, the opening is no longer needed and usually closes or becomes very small within several weeks or months. If the hole does not close it is called an Atrial Septal Defect (ASD). ASD is a congenital heart defect meaning its present since birth.
HOW WILL IT AFFECT YOU HEART?
Because of the ASD oxygenated blood from the left side of the heart leaks into the right side and if the defect is large it causes a significant volume overload on the right side of the heart. The right side now ends up pumping extra blood than it was supposed. This can cause damage to you heart as well as your lungs making them work harder than they were supposed to. If the hole is small it may not cause any symptoms
WHAT ARE THE SYMPTOMS OF ASD AND WHEN TO SEE A DOCTOR?
Patient with small defects that do not cause significant volume overloading of the right side of the heart may be asymptomatic. Those with larger defects can present with any of the following
•Poor appetite, poor growth, recurrent chest infections such as pneumonia
•Shortness of breath especially with exercise
•Decreased exercise tolerance, easy fatigue ability, palpitations , irregular heart beats
•And if left untreated it can lead to Heart Failure and / or increased pressure in the lungs , known as Pulmonary Hypertension
•ASD has also been associated in some clinical trials with stroke and migraine
That is why it is recommended to get the ASD closure done in childhood before it causes irreversible damage to the heart and the lungs. More often than not ASD is incidentally detected on routine health checkup for an unrelated problem.
WHAT INVESTIGATION MIGHT BE NEEDED?
•Clinical examination by your doctor may reveal an abnormal sound (murmur)
•ECG ( Electrocardiogram) may reveal abnormalities that can alert your doctor to the possibility of presence of ASD
•Chest X – Ray can show evidence of enlarged heart
•Echocardiography – this test is an ultrasound of the heart which can diagnose and size the ASD. Occasionally you may also need to get a Transesophageal Echocardiography
•Cardiac Catheterization may be done by your cardiologist prior to planned closure of the ASD.
Most of the time an Echocardiography alone suffices to diagnose ASD.
HOW CAN THE ASD BE TREATED?
There are two ways in which the ASD can be closed when indicated. One by percutaneous device closure through a very small puncture (< than 5 mm in size) in the blood vessels and secondly, in case percutaneous device closure is not possible then by open heart surgery. With tremendous advance in Intervention Cardiology more and more of these ASD closure are now being done through minimally invasive techniques that allows short hospital stay, early mobilization and return to normal life activities after the surgery.