Sometimes, congenital heart defects manifest for the first time in adulthood. One such defect is the atrial septal defect (ASD), a “hole” between the upper chambers of the heart, the left atrium and right atrium.
There are 3 major types of ASD: the secundum ASD, the primum ASD, and the sinus venosus ASD. Each has distinguishing anatomical features, but today, for the most part, we’ll consider them as group.
We won’t consider another type of “hole” between the upper chambers of the heart, the patent foramen ovale (PFO). In fetal life, the foramen ovale is a small hole which can persist after birth. A PFO is usually small and ordinarily does not pose risk to the patient or athlete.
How is an ASD Discovered?
In adulthood, an ASD is often discovered incidentally during a diagnostic test such as an echocardiogram. Adults can have no symptoms and be unaware of the defect. If there are symptoms, an ASD can produce fatigue, arrhythmias, heart failure, or stroke. An echocardiogram can delineate the exact type of ASD and also screen for any other types of structural heart disease which may be present.
A little bit of an aside for perspective….
In large-scale screening of school-aged athletes with echocardiograms, approximately 2% of individuals are found to have a structural heart problem. Approximately one third of those defects are ASDs.
What are the Consequences of an ASD?
If the ASD is large enough (approxim. 1.0 cm or more), blood will flow through the defect in a left-to-right direction. This results in extra blood in the right side of the heart and extra blood pumped to the lungs. We can quantify the amount of extra blood flow to the lungs as a shunt fraction, or Qp:Qs ratio. We say that the shunt is significant if the Qp:Qs ratio is greater than 1.5. This indicates that the blood flow to the lungs is 50% greater than normal.
If left untreated, the extra blood flow through an ASD can lead to enlargement of the right atrium and ventricle and irreversible changes to the pulmonary arteries that results in pulmonary hypertension.
Athletes should be aware that a large ASD may result in decreased exercise capacity.
Closure of ASD
We generally recommend closure of an ASD if:
1. The shunt fraction is >1.5.
2. There is evidence of enlargement or failure of the right heart chambers.
Many secundum ASDs can be closed with devices that are deployed by catheters threaded to the heart through the body’s blood vessels. We call this procedure a percutaneous device closure. This procedure is generally performed by a cardiologist and involves the procedure followed by a short hospital stay.
Ostium secundum and sinus venosus ASDs require conventional heart surgery for closure. These procedures are performed by a cardiac surgeon. Healthy patients usually require a short hospital stay after the operation.
The peri-procedural risk of these procedures is very low.
How quickly an athlete may return to their sports will depend upon the particular method of closure and also upon the demands of an athlete’s sport. This issue should be part of a discussion with the doctor before the procedure.
Recommendations for Athletes
The Congenital Heart Disease Task Force for the 36th Bethesda Conference on Eligibility Recommendations for Competitive Athletes with Cardiovascular Abnormalities made several recommendations for athletes with ASD:
1. Those with a small ASD, normal right heart volume, and no pulmonary hypertension can participate fully.
2. Those with a large ASD and no pulmonary hypertension can participate fully.
3. Those with an ASD and mild pulmonary hypertension can participate in low-intensity sports. Any athlete with ASD and associated cyanosis and large right-to-left shunt cannot participate in competitive sports.
4. After a satisfactory recovery, athletes can participate fully after ASD repair (device closure or surgical) after a period of 3-6 months.
5. After ASD closure, if an athlete has pulmonary hypertension, arrhythmias, heart block, or impaired heart function, there must be an individualized approach to the issued of continued participation.