Congenital heart defects (also called congenital heart diseases) are structural abnormalities that are present in the heart at birth.
What is an Atrial Septal Defect?
An atrial septal defect (ASD) is a hole in the septum, or muscular wall, which separates the heart’s two upper chambers (the atria). An ASD occurs when part of the atrial septum does not form properly.
Types of ASDs
Within the broad category of atrial septal defects, there are several types of defects. ASDs are classified by where they occur and their size.
A secundum ASD allows blood to flow from the left chamber to the right chamber or the right chamber to the left chamber, depending on pressures in the atria.
A patent foraman ovale (PFO) is a “flap” that is present when the atrial septum does not close properly at birth. A PFO allows blood to flow from the right atrium to the left atrium. This type of defect generally opens only during certain conditions when there is more pressure inside the chest, such as straining during a bowel movement, coughing, or sneezing. For more information about PFOs, click here: http://www.clevelandclinic.org/heartcenter/pub/guide/disease/congenital/pfo.htm
More complicated and rare types of ASDs also involve abnormal blood return from the lungs (sinus venosus) or heart valve abnormalities (primum ASDs).
What causes ASDs?
About 10 percent of congenital heart problems are caused by specific genetic defects, 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 atria 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.
Most congenital heart defects are likely due to maternal environmental factors combined with genetic predisposition and other medical conditions (Down’s syndrome, for example). Environmental factors include alcohol and street drugs, as well as diseases such as diabetes, lupus and rubella. Sometimes a viral infection can cause heart defects to develop. In about 95% of the cases, no cause can be identified.
Who is affected by ASDs?
ASDs account for about 7 percent of all congenital heart defects, making them the third most common type. ASDs occur more frequently in females than in males.
What are the long-term effects of ASDs?
Normally, the right side of the heart pumps blood low in oxygen to the lungs, while the heart’s left side pumps oxygen-rich blood to the body. When there is an ASD, blood from the left and right sides mix, and the heart does not generally work at its most efficient level.
The risk of problems is greater when the size of the defect is large (greater than 2 cm). Problems may include:
- Right heart enlargement (right heart failure)
- Heart rhythm disturbances including atrial fibrillation or atrial flutter: Occur in 50 to 60 percent of ASD patients over age 40
- Stroke
- Pulmonary hypertension (high blood pressure in the arteries that supply the lungs). If pulmonary hypertension is severe, flow across the ASD (normally left to right) can reverse (become right to left). As a result, oxygen levels in the blood will decrease, leading to a condition known as Eisenmenger syndrome.
- Leaking tricuspid and mitral valves as a result of the enlargement of the heart
What are the symptoms of an ASD?
Although ASDs are present at birth, there are usually no associated symptoms, and they can go undetected until adulthood. In some patients, the defect is discovered accidentally during a chest X-ray that reveals enlargement of the right side of the heart.
By age 50, an individual with an ASD may start having symptoms such as shortness of breath, fainting, irregular heart rhythms or fatigue after mild activity or exercise.
In people with PFO, a stroke may be the first indication of the defect. Over forty percent of people who have a stroke but do not have any other risk factors are found to have PFO.
How is an ASD diagnosed?
An assessment for ASD may include:
- ECG – an electrocardiogram, a graph of the heart’s electrical activity (heartbeat)
- Chest X-ray – to evaluate the size of the heart and lungs
- Transthoracic echocardiography/Doppler examination – an ultrasound image of the heart combined with measurements of blood flow to assess the heart’s structure and function
- Transesophageal echocardiography (TEE)/Doppler examination – an ultrasound image obtained via the esophagus to provide a clearer image of the atria, more precisely define the defect’s size and shape and to evaluate the health of the heart valves. Using TEE, the physician can easily distinguish a PFO from other types of ASD.
- Intracardiac echocardiography (ICE)/Doppler examination – an ultrasound image obtained by inserting a tiny camera (echo probe) within the chambers of the heart via a peripheral vein. This study also can define the size and shape of the defect and the direction of blood flow across it. ICE is often used to guide percutaneous (nonsurgical) repair of the defect.
- Right heart catheterization – a procedure during which a small thin tube (catheter) is inserted into the heart via the peripheral vein. Pressures are measured in each chamber as well as the oxygen saturations (how much oxygen is present in the blood). The latter measurements determine how much blood is flowing across the defect by measuring how much the oxygen level increases beyond the site of the defect. The defect can also be crossed using a catheter and contrast dye can be injected into the left atrium to size the defect (atrial angiogram).
- Left heart catheterization – during this procedure angiography (injecting dye into the blood vessels of the heart by way of a catheter) can be performed to determine the presence of significant coronary artery disease.
How is an ASD treated?
When an ASD is confirmed, treatment depends on the type and size of the defect, its effect on the heart, and the presence of any other related conditions, such as pulmonary hypertension, valve disease or coronary artery disease.
In general, when a patient has a large ASD causing significant shunting (flow of blood through the defect) and right-sided heart enlargement, Cleveland Clinic specialists recommend correcting the defect.
The size of the defect correlates with the degree of shunting; the more shunting, the greater the risk of long-term complications such as atrial fibrillation and pulmonary hypertension. The degree of shunting is determined by TEE, MRI or oxygen saturations; and the degree of right heart enlargement, as measured by echocardiogram, usually correlates with the degree of shunting.
ASD Repair
Nonsurgical Treatment
Nonsurgical, percutaneous (through the skin) repair is the preferred treatment for most secundum ASDs, but surgery may be needed to repair other types of ASDs (see Surgery section below for more information). Your doctor will determine what type of repair procedure is best for you.
Two different brands of closure devices are approved by the U.S. Food and Drug Administration for percutaneous ASD, including the Amplatzer Septal Occluder and the GORE HELEX® Septal Occluder.
The closure devices differ in design, but the placement method and their function are similar:
The device is attached to a catheter, which is inserted into a vein in the groin and advanced to the heart and through the defect, guided by X-ray. As the device is slowly pushed out of the catheter, it opens up to cover each edge of the defect, sealing it closed. Over time, tissue grows over the implant and it becomes part of the heart.
Before a percutaneous closure device procedure, the patient will have a cardiac catheterization to determine the size and location of the defect. Pressures inside the heart chambers will also be measured.
For at least the first 6 months after the repair, the patient will need to take an anticoagulant such as aspirin or warfarin (Coumadin) to prevent clots from forming on the device.
AMPLATZER Septal Occluder® used for ASD repair
Photo used with permission from AGA Medical Corporation
The AMPLATZER® Septal Occluder is a transcatheter closure device used to treat ASD defects. It consists of two Nitinol wire mesh discs filled with polyester fabric. It is folded into a special catheter, similar to the catheter used during a catheterization. The catheter is inserted into a vein in the leg, advanced into the atrial septum and through the defect. When the catheter is in proper position, the device is slowly pushed out of the catheter until the discs of the device sit on each side of the defect (like a sandwich). The two discs are linked together by a short connecting waist that matches the size of the defect. The discs and the waist are filed with polyester fabric to increase the device's closing ability. Over time, heart tissue grows over the implant, and it becomes part of the heart, correcting the defect.
GORE HELEX® Septal Occluder used for ASD repair
Photo used with permission from W.L. gore & Associates, Inc.
The GORE HELEX® Septal Occluder is a transcatheter closure device used to treat ASD defects. It is a disc-like device that consists of an ePTFE patch material supported by a single Nitinol wire frame.
The device is folded into a special catheter and inserted into vein in the leg. Using a guide wire, the device is advanced into the atrial septum and through the defect. When the catheter is in the correct position, the device is slowly pushed out of the catheter until it covers the defect. The device bridges the septal defect. Over time, heart tissue grows over the implant, and it becomes part of the heart, correcting the defect.
For more information on the cardiac implant closure device procedure, Click here.
Surgical Repair
Prior to the introduction of percutaneous techniques, surgical closure was the only treatment option for an ASD, regardless of the type of defect. Surgical repair may be needed for large secundum atrial septal defects and other types of ASDs.
Surgical repair is usually performed using a tissue patch, preferably from the patient’s own pericardium. Some secundum ASDs can be surgically closed with sutures alone.
For more information about surgical repair, please see:
Web chat transcript: Adult Congenital Heart Disease Surgery – Featuring Gosta Pettersson, MD, PhD
Follow-Up Care
If a procedure was performed to correct the defect, the patient usually returns to the cardiologist 3, 6 and 12 months after the procedure for a follow-up physical exam and echocardiogram, and annually thereafter. After a secundum ASD is repaired, most people can return to their regular activities without any activity restrictions or further treatment needed. People who have other heart problems such as coronary artery disease or pulmonary hypertension may need to take medications.
If you had heart surgery to repair a defect or if you received a transcatheter closure device, your doctor will prescribe preventive antibiotics for you to take before certain medical procedures for at least 6 months after the repair procedure to reduce the risk of infective endocarditis. Your doctor can provide specific guidelines about when to take antibiotics. According to the American Heart Association, after 6 months, there is insufficient data to make recommendations for continuing preventive antibiotic therapy. For more information about endocarditis, click here
References
Krasuski, RA, MD. When and how to fix a ‘hole in the heart’: Approach to ASD and PFO. Cleveland Clinic Journal of Medicine. 2007 Feb; 74(2):137-47.
www.ccjm.org/PDFFILES/Krasuski2-07.pdf
Shunichi H, et al. Effect of medical treatment in stroke patients with patent foramen ovale. Circulation. 2002 ;105(22):2625-31. http://circ.ahajournals.org/cgi/content/full/105/22/2625
For More Information
Cleveland Clinic Heart and Vascular Institute specialists are among the most experienced in the world in treating adult congenital heart defects, such as ASD. If you need more information, click here to contact us , chat online with a nurse or call the Heart and Vascular Institute Resource & Information Nurse at 216/445-9288 or toll-free at 866/289-6911. We would be happy to help you.
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