Atrial Septal Defect Health Article

Definition

An atrial septal defect (ASD) is an abnormal opening in the muscular wall separating the left and right upper chambers (atria) of the heart.

Description

During normal development of the fetal heart, there is an opening in the wall (septum) separating the left and right upper chambers of the heart. Normally, the opening closes before birth, but if it does not, the child is born with a hole between the left and right atria. This abnormal opening is called an atrial septal defect and causes blood from the left atrium to flow (or "shunt") across the hole into the right atrium.

Different types of atrial septal defects occur, and they are classified according to where in the separating wall they are found. The most commonly found atrial septal defect, called secundum atrial septal defect, occurs in the middle of the atrial septum and accounts for about 70 percent of all atrial septal defects.

Abnormal openings also form in the upper part of the atrial septum (called sinus venosus ASD) where the superior vena cava and right atrium join, and lower parts of the atrial septum (called primum ASD). A sinus venosus ASD usually involves the right upper pulmonary vein, while a primum ASD often occurs along with an abnormality in the mitral valve and/or tricuspid valve, and causes some blood leakage (regurgitation) back through the valves.

Atrial septal defects can occur alone or in combination with other congenital heart disorders, such as ventricular septal defect. They can be as small as a pinpoint or as large as the space where the entire septum should be located.

Demographics

Atrial and ventricular septal defects are the most common congenital heart defects. Atrial septal defect accounts for 4–10 percent of all cases of congenital heart disease in the United States. Abnormal openings in the atrial septum are twice as common in females as in males.

Causes

Abnormal openings in the atrial septum occur during fetal development. These abnormalities can go unnoticed if the opening is small and produces no abnormal symptoms. If the defect is large, oxygen-rich blood from the left atrium flows back into the right atrium and gets pumped back to the lungs again, causing more work for the heart and lungs. The right atrium may swell or enlarge to hold the extra blood.

In some cases, an atrial septal defect can allow blood clots from the body to enter the brain and cause a stroke. Untreated atrial septal defect can lead to pulmonary hypertension, chest infection, Eisenmenger's syndrome, atrial fibrillation, atrial flutter, stroke, or right-sided heart failure.

Symptoms

A person born with an atrial septal defect may have no symptoms in childhood, and the condition may go undetected into adulthood. Stunted growth may be a symptom of atrial septal defect. Other symptoms that might develop over time include:

• shortness of breath
• fainting
• irregular heart beats or palpitations (abnormal heart beats that feel like fluttering in the chest)
• inability to exercise without becoming over-tired
• difficulty breathing with exercise or activity

By age 50, most people with atrial septal defects experience symptoms that interfere with activities of daily living.

When to call the doctor

The parent or caregiver should call the child's pediatrician or cardiologist when the child has these symptoms or conditions:

• swelling in the ankles or feet
• swollen abdomen
• poor exercise tolerance
• recurrent chest colds and respiratory infections
• abnormal blood pressure
• signs of infection, including sore throat, general body aches, or fever

The parent or caregiver should seek emergency treatment by calling 911 in most areas when the child has these symptoms or conditions:

• breathing difficulties or rapid breathing
• dizziness or fainting
• uncontrolled coughing or coughing with blood
• bluish skin tone or bluish coloration around the lips, fingernail beds, and tongue
• irregular heart beats or palpitations (abnormal heart beats that feel like fluttering in the chest)
• chest pain (rare in children)