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What is an ASD?
Atrial septal defect (ASD) is a hole in the wall (the septum) between the
heart’s two uppermost chambers, the right and left atrium. This hole allows
blood to flow in either direction between the left and right atrium.
ASDs may cause several problems. First, this creates a condition in which the
right side of the heart now contains extra blood, and extra blood also now flows
to the lungs. This diversion of blood puts strain on the heart because it has to
pump this extra blood to the lungs. This extra blood flow to the lungs may
damage the arteries to the lungs over time, leading to high blood pressure in
these vessels. In addition, the strain put on the right-sided pumping chamber
can lead to a weakening or enlargement of the right side of the heart and
eventually heart failure, if left untreated. This enlargement may also cause
arrhythmias (irregular heart rhythms) to develop. Also, ASDs in some
circumstances can allow blood clots from the body to enter the brain and cause a
stroke.
What are the symptoms of an ASD?
Most patients do not have any symptoms in childhood. However, symptoms that
might develop over time, depending on the severity of the ASD and other factors,
include:
- shortness of breath, fatigue, and labored breathing while
exercising
- irregular heart beats
- transient ischemic attacks (TIA), which result in stroke-like
symptoms
- stroke
- pulmonary hypertension, which is high blood pressure in the
arteries of the lung, and can lead to heart failure if not treated
- reduction in lifespan of about 20 years on average if the ASD
is not closed
What causes ASD?
An ASD is congenital, meaning it is a defect that is inborn or exists at
birth. Stated another way, the defect is an abnormality, not a disease. The
septum between the two atrium of the heart did not develop normally before
birth. What is known is that about 20 percent of ASDs that occur
in infants close on their own in the first years of life.
Heart defects in general. Sometimes a viral infection can cause heart
defects to develop, other causes include genetic factors, certain other medical
conditions (Down’s syndrome, for example), some prescription and
nonprescription drugs, but about 95% of the time no cause can be identified.
How is an ASD diagnosed?
During a routine examination, your doctor may hear a murmur when listening to
the heart. A heart murmur is an additional sound, a swishing sound heard in the
heart. If a murmur is identified, your doctor will order other tests that can
include:
- electrocardiogram (ECG or EKG) - a test that records
the electrical changes that occur during a heartbeat; reveals abnormal heart
rhythms (arrhythmias) and detects heart muscle stress
- chest X-ray - a test to show the size and shape of the
heart and lungs
- echocardiogram - a test that uses sound waves to
create a moving picture of the heart’s internal structures.
- doppler
ultrasound is a test that uses sound waves to measure blood flow; often
combined with echocardiogram to evaluate both the internal structure of the
heart and blood flow across the heart’s valves
- cardiac magnetic resonance imaging (MRI) - a test that
uses three-dimensional imaging to reveal how blood flows through the heart
and how the heart is working
- cardiac catheterization - a procedure that involves
inserting a thin tube (a catheter) into a vein or artery and passing it into
the heart to sample the level of oxygen, measure pressure changes, and make
x-ray movies of the heart and its internal structures.
- angiography is
a dye-enhanced x-ray of the heart’s internal structures
- additional tests may be ordered as necessary
How is an ASD treated?
If you or your child is diagnosed with an ASD, your primary care doctor will
recommend that you meet with a Congenital Heart Specialist (a doctor who has the
training and equipment to determine the heart problem) who will order the
necessary special tests, medical care, heart surgery, and follow-up checkups.
The best treatment approach will depend on the patient’s symptoms as well as
the size of the ASD. The ASD may need to be closed surgically through open-heart
surgery or may be repaired through an outpatient catheter-based procedure. To
learn more about this procedure, see the document, "How is a ASD
Closed Using a Catheter-based Procedure."
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