Atrial Septal Defects
The normal heart is composed of four chambers. The upper chambers are called “right and left atria” while the lower chambers are called “right and left ventricles.” The right atrium receives deoxygenated blood from systemic veins and then connects to the right ventricle. The left atrium receives oxygenated blood from the pulmonary veins and connects to the left ventricle. The right ventricle pumps into the main pulmonary artery where blood gets oxygenated. The left ventricle pumps into the aorta thus providing oxygenated blood to the rest of the body.
Separating the upper chambers is a thin membranous structure called the inter-atrial septum. Separating the lower chambers is a thicker membranous structure called the inter-ventricular septum. Every child is born with a small opening in the inter-atrial septum but none in the inter-ventricular septum. The opening in the inter-atrial serves a very important function prior to birth. After birth, the opening is no longer needed and usually closes within a few months.
If the hole does not close within the upper chambers, a condition known as atrial septal defect (ASD) arises. ASD is a type of congenital heart defect (present at birth). In this condition, oxygenated blood from the left atrium flows through this hole into the right atrium (non-oxygenated blood). This mixture causes an increase in the amount of blood flowing toward the lungs. If not properly addressed, it can lead to heart failure, pulmonary hypertension or heart arrhythmias.
Causes of Atrial Septal Defects
Doctors know that heart defects present at birth (congenital) arise from errors early in the heart's development, but there's often no clear cause. Sometimes atrial septal defects tend to be more common in generations of a family.
Symptoms of Atrial Septal Defects
Many people born with this condition have no signs or symptoms. However, as the condition worsens symptoms may start to appear. Symptoms may include:
- Shortness of breath, especially when exercising.
- Fatigue
- Swelling of legs, feet or abdomen.
- Heart palpitations
- Heart murmurs
Diagnosis of Atrial Septal Defects
To diagnose atrial septal defects, your doctor will perform a variety of tests, including but not limited to:
- Electrocardiogram (EKG/ECG)
- Echocardiogram (ECHO)
- X-Rays
- Magnetic resonance imaging (MRI)
- Cardiac catheterization
Treatment of Atrial Septal Defects
Many atrial septal defects close on their own during childhood. For those that don't close or those that are small, treatment may not be required. However, it is very important to keep it monitored. Moderate to large ASDs may eventually require to be closed. Some treatment options include the use of medications or a surgical procedure called atrial septal defect surgery (includes transcatheter options).
Though medications will not be able to repair the hole, medications can reduce some of the signs and symptoms present for those with a longstanding atrial septal defect. Drugs may also be used to reduce the frequency of irregular heartbeat (arrhythmia) that can occur when an atrial septal defect has not been treated. Adults with these atrial septal defects can have an increased risk of blood clots within the heart and may thus require anticoagulants (blood-thinners).