ATRIAL SEPTAL DEFECT
is Atrial Septal Defect (ASD)?
Normal anatomy of the heart: The normal heart consists of 4 chambers - the right & left atrium
(These are the chambers that receive the blood - the right atrium receives
impure blood from the rest of the body and left atrium receives pure
blood from the lungs.) and the right & left ventricles (These are
the chambers that pump the blood from the heart – right ventricle
receives blood from right atrium and pumps the impure blood to the lungs
via the pulmonary artery and left ventricle receives pure blood from
the left atrium and pumps the pure blood to the rest of the body via
another artery called as the aorta). The impure blood in the right atrium
is separated from pure blood in the left atrium by the atrial septum.
A hole in this septum leads to blood flow from left atrium to the right
atrium. This is because the pressure of blood in left atrium is higher
than that of the right atrium.
happens in an ASD?
As the right atrium receives blood from 2 places- impure blood from
rest of the body and pure blood from left atrium, more blood reaches
the right ventricle. The ventricle now has to pump harder to send this
increased amount of blood into the lungs. As a result extra blood flows
into the lungs than it normally does. This extra blood flow in the lungs
can cause frequent chest infections. On chronic high blood flow, the
blood vessels in the lungs become hard and thick leading to high pressure
in the pulmonary vessels. This condition is called pulmonary hypertension.
Subsequently the heart may also fail as the right ventricle may become
weak due to constant hard work. These changes take many years to develop.
Another problem with ASD is arrhythmia (irregular rhythm of the heart).
This occurs as the right atrium enlarges in size due to increased blood
volume. That causes a disturbance in the heart's electrical activity
causing it to beat faster leading to a condition called as Atrial Fibrillation.
All these changes are seen with large ASD.
Many children with small ASD are not even symptomatic till they are
in their 30’s or 40’s.
Sometimes clots may enter the right atrium and pass through the ASD
into left atrium which then passes into the aorta and to the brain leading
to a stroke – phenomenon known as paradoxical embolization. (Blood
flow in the veins is sluggish and some clots may form. In a normal person,
the clots pass from the right atrium to the lungs where they are filtered
and prevented from entering into the pure blood). It is because of this
risk, that even a small ASD needs to be closed.
is ASD diagnosed?
ASD is suspected on clinical examination by fixed splitting of the second
heart sound and confirmed by echocardiography (ultrasound of the heart).
an ASD be closed?
Yes. Most ASD require to be closed. Sometimes a small ASD such as a
stretched PFO may be left untouched.
should an ASD be closed?
Most children with ASD are totally asymptomatic and the ASD is detected
on routine check-up. Although there is no urgency, ASD should be closed
as soon as possible to avoid the risk of heart failure or paradoxical
Patients with associated heart defects such as PAPVC [Partial Anomalous
Pulmonary Venous Circulation- a defect where the pulmonary veins instead
of carrying the pure blood from lungs to the left atrium connect to
the right atrium], Mitral valve clefts or VSD [Ventricular septal defects
- Hole in the septum between both the ventricles] need to be operated
early in life as these children develop heart failure soon.
is ASD treated?
transcatheter closure: A catheter is passed into the
blood vessel in the groin or the forearm and threaded into the heart.
Through this catheter a special umbrella device is pushed across the
ASD and opened. The umbrella which is fixed in place now blocks the
operation- The defect in the atrial septum is stitched
using a special thread. In case the ASD is large, it is closed with
a “ Patch” stitched in place. This patch is usually
of the patient’s own tissue such as the pericardium (the covering
of the heart) or synthetic material such as silk cloth or Dacron.
invasive Heart Surgery- Through 3 or 4 small holes in the
chest, specially designed instruments are passed in to the chest
and used to repair ASD.
Depending on a particular patient, the treating physician can decide
which is the best procedure for closure of ASD for that patient.
After surgery, hospital stay is usually 5 to 7 days while with catheter
based & minimal invasion methods, the patient is discharged in a
couple of days.
there any complications of ASD closure?
ASD surgery is a safe procedure. Risk of death after ASD repair is below
1% and major complication are rare. Rarely, bleeding may be excessive.
there any problems post repair?
Patients return to a normal and productive life. There is no need for
long-term medications and complications are rare depending on the degree
of pulmonary hypertension prior to surgery.
created on 6-05-2003
updated on 18-11-2006