Atrial Septal Defects

Heart With Atrial Septal Defects

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An Atrial Septal Defect, or ASD, is a hole in the wall between the right and left atria (atrial septum). In the presence of an ASD, blood flows from the higher pressure left atrium to the lower pressure right atrium.

When this happens, the oxygen-rich blood of the left atrium is redirected through the right side of the heart and back to the lungs. The right atrium, right ventricle, and pulmonary artery may enlarge due to the increased blood flow through these structures.

Long-term side effects of an untreated ASD include atrial arrythmias (loss or abnormality of rhythm), ventricular dysfunction, and pulmonary vascular obstructive disease (a condition in which the pulmonary arteries become thickened due to high blood flow). For these reasons, it is preferential to close even small ASDs early in life to prevent complications later in life.

Three Types of ASD

 
Secundum-Type ASD

Secundum-type ASDs are the most common, comprising approximately 85% of all ASDs. In many cases, infants and young children are asymptomatic and the ASD may not be detected until school age or later. Approximately 20% of secundum-type ASDs close spontaneously in the first year of life. Often, a heart murmur, associated with the increase in blood flow across the pulmonary valve, is the symptom that causes a physician to investigate further. The diagnosis of an ASD is confirmed by echocardiography.

In a secundum-type ASD, the hole is located in the central part of the atrial septum. The methods of treatment for a secundum-type ASD consist of surgical repair or a catheter technique. Options for surgical repair involve suture closure (reserved for small ASDs) or patch closure. The patch material may be a portion of the patients own pericardium (the sac around the heart) or a synthetic material. The catheter technique involves closure of the ASD with a synthetic device that plugs the hole. The device is introduced through a heart catheter which is passed through a vein in the leg that leads up to the heart. Initially, the device is held in place by the natural pressures created within the atria. Over time, the device acts as a framework over which normal tissue grows.

 
Sinus Venosus ASD

Sinus venosus atrial septal defects constitute 5% to 10% of all ASDs. In a sinus venosus ASD the hole is located in the upper portion of the atrial septum. This type of ASD is often associated with anomalous drainage of the right, upper pulmonary veins. In other words, the pulmonary veins, which normally carry oxygenated blood from the lungs to the left atrium, drain into the right atrium instead. There is no chance for spontaneous closure of this type of ASD. For this reason, surgical repair is necessary for patients with this type of ASD.

 
Primum-Type ASD

Primum-type ASDs constitute between 5% and 10% of all ASDs. In a primum-type ASD the hole is located in the lower part of the atrial septum. Frequently, abnormalities of one or more heart valves (most often the mitral valve) are associated with this defect. Unlike the secundum-type ASD, symptoms of this type of ASD are seen during early childhood. Surgical repair is the only method of treatment for a primum type ASD since there is no chance of spontaneous closure.


What Is Normal Cardiac Anatomy?

When your child has a congenital heart defect, there's usually something wrong with the structure of his or her heart's structure.

 
Learn More About Normal Cardiac Anatomy

Heart With Normal Cardiac Anatomy

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When your child has a congenital heart defect, there's usually something wrong with the structure of his or her heart's structure.

The heart is composed of four chambers. The two upper chambers, known as atria, collect blood as it flows back to the heart. The two lower chambers, known as ventricles, pump blood with each heartbeat to the two main arteries (the pulmonary artery and the aorta). The septum is the wall that divides the heart into right and left sides. The atrial septum separates the right and left atria; likewise, the ventricular septum separates the two ventricles.

There are four valves that control the flow of blood through the heart. These flap-like structures allow blood to flow in only one direction. The tricuspid and mitral valves, also known as the atrioventricular valves, separate the upper and lower chambers of the heart. The aortic and pulmonary valves, also known as the arterial valves, separate the ventricles from the main arteries. Oxygen-depleted blood returns from the body and drains into the right atrium via the superior and inferior vena cavas. The blood in the right atrium then passes through the tricuspid valve and enters the right ventricle.

Next, the blood passes through the pulmonary valve, enters the pulmonary artery, and travels to the lungs where it is replenished with oxygen. The oxygen-rich blood returns to the heart via the pulmonary veins, draining into the left atrium. The blood in the left atrium passes through the bicuspid, or mitral, valve and enters the left ventricle.

Finally, the oxygen-rich blood flows through the aortic valve into the aorta and out to the rest of the body.

Congenital Heart Defects

What Is a Congenital Heart Defect?

A congenital heart defect is a problem in the heart's structure that is there when a baby is born. Heart defects can range from mild to severe.

What Causes a Congenital Heart Defect?

Congenital heart defects happen because of incomplete or abnormal development of the fetus' heart during the very early weeks of pregnancy. Some are known to be associated with genetic disorders, such as Down syndrome.

But the cause of most congenital heart defects isn't known. While they can't be prevented, many treatments are available for the defects and related health problems.

Common Heart Defects

Common types of congenital heart defects, which can affect any part of the heart or its surrounding structures, include:

What Are the Signs & Symptoms of a Heart Defect?

Because congenital defects often affect the heart's ability to pump blood and to deliver oxygen to the tissues of the body, they often produce telltale signs such as:

  • a bluish tinge or color (cyanosis) to the lips, tongue, and/or nailbeds
  • an increased rate of breathing or difficulty breathing
  • poor appetite or difficulty feeding
  • failure to thrive (weight loss or failure to gain weight)
  • abnormal heart murmur
  • sweating, especially during feedings
  • a weaker pulse

If you notice any of these signs in your baby or child, call your doctor right away. If your doctor notices these signs, you may be referred to a pediatric cardiologist (a doctor who specializes in treating heart problems).

How Is a Heart Defect Diagnosed?

Some congenital heart defects cause serious symptoms right at birth. For those, a baby will go to the newborn intensive care unit (NICU) in the hospital for immediate evaluation by a cardiologist. Other defects might not be diagnosed until the teen years — or even adulthood.

Newborn Screening

Newborns in the U.S. are screened at least 24 hours after birth to look for serious congenital heart problems that can lower oxygen levels. This screen is a simple, painless test using a machine called a pulse oximeter. The oximeter uses a sensor put on a baby's skin that estimates how much oxygen is in the baby's blood. This test can help spot heart problems early on so that they can be treated right away. The screening will find most serious heart defects, but some babies who test normal could still have a problem, especially COA or other defects on the left side of the heart.

Testing

After a complete physical exam, including evaluation of the baby's heart rate and blood pressure, the cardiologist will order an electrocardiogram (EKG).

The cardiologist will probably order an echocardiogram — a test that uses sound waves to create a picture of the heart and its circulation. Echocardiograms are the primary tool for diagnosing congenital heart defects.

A fetal echocardiogram is a specialized type of ultrasound that allows diagnosis of heart problems in utero. This can be done as early as 16–18 weeks into the pregnancy. These tests are ordered when a possible heart abnormality is seen on a level II ultrasound. They're also done if another close family member has a congenital heart defect or if the mother has a condition, such as diabetes, that might make a heart problem in the fetus more likely.

Sometimes, doctors order a chest X-ray or a cardiac catheterization.

When Should I Call the Doctor?

If you think your child may have a heart problem or you notice any signs (such as difficulty breathing or feeding, or blue lips or tongue) that concern you, call your doctor. If your baby suddenly turns very blue or loses consciousness, call 911.

More treatments than ever are available for congenital heart defects, and most defects are treated successfully. Children with heart problems are best cared for by a team of specialists, which usually will include:

  • pediatric cardiologists
  • pediatric heart surgeons
  • pediatric cardiac anesthesiologists
  • doctors specialized in the intensive care of children with heart problems and specialized nurses, nurse practitioners, physician assistants, and many others

Many kids with heart problems benefit from having their hearts fixed surgically or through a cardiac catheterization procedure. The sooner they get medical attention, the better the chances for the fullest recovery possible.

With all the medical resources available, a congenital heart defect won't necessarily prevent a child from leading a normal life. By working with the health care team, you'll get the best care possible for your child.

Reviewed by: Steven Dowshen, MD
Date reviewed: October 30, 2017