Cardiac Center

Anomalous Left Coronary Artery From the Pulmonary Artery (ALCAPA)

Before you begin reading about ALCAPA, please read the explanation of how the normal heart works for a basic understanding of its structure and function.

What is anomalous left coronary artery from the pulmonary artery (ALCAPA)?

The heart is a two-sided pump. The right side of the heart pumps blood that has little oxygen to the lungs to pick up more oxygen. The pulmonary artery is the large blood vessel that carries blood from the right side of the heart to the lungs.

Anomalous Left Coronary Artery From the Pulmonary Artery (ALCAPA)
View ALCAPA Illustration
After the blood passes through the lungs, now with oxygen, the left side of the heart pumps the oxygenated blood back out to the body through a large artery called the aorta. Other arteries branching from the aorta carry the oxygenated blood to feed organs and other parts of the body.

The coronary arteries are the blood vessels that carry blood to feed the heart. The left coronary artery feeds the left side of the heart, and the right coronary artery feeds the right side.

In a normal heart, both coronary arteries arise (branch) from the aorta. In ALCAPA, something goes wrong while the heart is forming in the womb, and the left coronary artery arises from the pulmonary artery instead of the aorta. Sometimes doctors call this heart defect “anomalous origin of the left coronary artery from the pulmonary artery.” Anomalous means irregular.

When the left coronary artery is attached to the pulmonary artery instead of the aorta, two main differences in the blood flow feeding the heart occur that can quickly cause the tissue of the heart to become damaged and die:

Coronary steal

The first problem is called “coronary steal.” When the left coronary artery is attached to the pulmonary artery, some of the blood flowing into the coronary artery never makes it to the heart. Instead, it flows back into the pulmonary artery, which “steals” the blood from the heart.

Why does this happen? The lungs are spongy and not as dense as other organs and parts of the body because they have so many small airways. In fact, the surface area of the lungs of an adult would cover a tennis court. With so much surface area, the lungs have a huge capacity for blood. “Vascular resistance” is a term that describes how much resistance blood encounters as it tries to flow into a certain area. The vascular resistance of the lungs is much lower than the vascular resistance of the body. In other words, blood flows into the lungs much more easily than to other parts of the body. Just like water, blood takes the path of least resistance, so coronary steal occurs when the blood flows back to the lungs through the anomalous left coronary artery in this way.

Less oxygen in the blood

The other problem is that blood in the pulmonary artery has much less oxygen (deoxygenated blood) than the blood in the aorta. Because in ALCAPA the left coronary artery arises from the pulmonary artery, it supplies the heart muscle with deoxygenated blood. When there is less overall oxygen in the blood, the heart muscle has less oxygen to take in to feed muscle cells.

The combination of coronary steal plus lower blood oxygen leads to the starvation of the heart muscle, which can cause heart muscle damage or death.


What are ALCAPA symptoms?

In an infant, ALCAPA symptoms can include:


How is ALCAPA diagnosed?

ALCAPA cannot be detected during pregnancy. In most cases ALCAPA is diagnosed in the first one to two months of life, after a parent or pediatrician notices symptoms. In rare cases, the child doesn’t have noticeable ALCAPA symptoms until he or she is a toddler or older.

Diagnosis of ALCAPA may include: 

In many cases cardiac catheterization will also be required. A thin tube is inserted into the heart through a vein and/or artery in either the leg or through the umbilicus (“belly button”).


What are ALCAPA treatment options?

Surgery is required to fix ALCAPA. There are a number of surgical procedures that can be used, including:

Your child’s team will discuss ALCAPA treatment options with you based on your child’s physiology.


What kind of follow-up care is required after ALCAPA treatment?

After the surgery, most patients with ALCAPA will experience a good quality of life. Some will have to remain on medicine, but many will be able to stop taking medicines within weeks or months of the surgery. Numerous appointments with a cardiologist will be required after the surgery, to make sure the child’s heart is working properly. 

As the child grows, a cardiologist will continue to monitor the heart, at annual appointments or more frequently if required. Many children who were born with ALCAPA do very well and don’t have any restrictions to school, activity or sports. However, children who are born with ALCAPA will require life-long care by a cardiologist. Because they are at higher risk for abnormal heart rhythms and because they were born with a heart defect, annual (or more frequent) visits with a cardiologist will be required.

Once children are older than 18 years, they will transfer to an adult cardiologist. The Philadelphia Adult Congenital Heart Center, a joint program of The Children’s Hospital of Philadelphia and the University of Pennsylvania, meets the unique needs of adults who were born with heart defects.


Reviewed by: Julie Brothers, MD, FAAP
Date: June 2013

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Anomalous Left Coronary Artery From the Pulmonary Artery

Learn about Quinn's experience with Anomalous Left Coronary Artery From the Pulmonary Artery (ALCAPA). Read Quinn's story