The heart is divided into four separate chambers. The upper chambers, or atria, are divided by a wall called the atrial septum.

An atrial septal defect (ASD) is a hole in that septum. Atrial septal defects are one of the most common heart defects, and are caused by incomplete growth of the septal wall during fetal development. When an atrial septal defect is present, blood flows through the hole, usually from the left atrium to the right atrium. This increases the blood volume in the right atrium, which causes more blood to be pumped to the lungs. This short circuit of blood flow is inefficient for providing circulation to the body.

In some infants and young children, an atrial septal defect may not result in any outward symptoms. A larger defect may allow so much blood flow through the hole that congestive heart failure symptoms such as shortness of breath, fatigue, and slow growth may be seen even in young children.

If a larger ASD is left untreated in children, atrial septal defect may cause problems such as failure to grow and develop normally, and an inability to gain weight. In adulthood, additional problems may include pulmonary hypertension (high blood pressure in the lungs), congestive heart failure (weakening of the heart muscle), atrial arrhythmias (abnormal rhythm or beating of the heart) and an increased stroke risk.

The ASD can be one hole, or a number of smaller holes. An ASD with a number of smaller holes is called a "multi-fenestrated atrial septal defect" and is sometimes described by physicians as looking like "Swiss Cheese" in the atrial septum wall.

Fenestrated Fontan

Fenestrated Fontan Palliation is a surgical procedure in which a "baffle" is constructed in the heart to help with blood circulation for hearts with multiple defects that can cause life-threatening heart dysfunction. During this procedure, the surgeon makes a small hole (fenestration) in the baffle to help relieve the symptoms of the heart disease. Fenestrated Fontan Palliation is often performed in infants and children, but may be performed in adults also to provide adequate circulation until additional procedures can be performed to establish more normal heart function.

The fenestration is a small hole created by the surgeon to permit a small amount of blood flow to go from the Fontan baffle directly to the left heart without going through the lungs. This is generally thought to be beneficial early after surgery. Once the patient has recovered from the operation, the cardiologist may feel the fenestration or small hole, is no longer needed, and the fenestration can be closed like an atrial septal defect.

Treating Atrial Septal Defects (ASD)

AGA Medical introduced the AMPLATZER® Septal Occluder, the first catheter delivered atrial septal closure device. Introduced most countries beginning in 1996, over 90,000 Septal Occluders have been manufactured and delivered worldwide to cardiac physicians to date.