Anomalous left coronary artery (ALCAPA) is a heart defect in which the left coronary artery (which carries blood to the heart muscle) is connected to the pulmonary artery instead of to the aorta.

ALCAPA is present at birth (congenital).

An anomalous left coronary artery is a problem that occurs when the baby's heart is developing, early in the pregnancy. The developing blood vessels in the heart do not connect correctly.

In the normal heart, the left coronary artery starts in the aorta -- the major blood vessel that takes oxygen-rich blood from the heart to the rest of the body.

In children with ALCAPA, the left coronary artery starts at the pulmonary artery -- the major blood vessel that takes oxygen-poor blood from the heart to the lungs.

When the left coronary artery starts in the pulmonary artery, it carries oxygen-poor blood to the left side of the heart. When the heart does not get enough oxygen, it begins to die, a condition leading to a heart attack in the baby.

A condition known as "coronary steal" further damages the heart in babies with ALCAPA. The low blood pressure in the pulmonary artery causes blood from the abnormal left coronary artery to flow toward the pulmonary artery instead of toward the heart. This results in less blood and oxygen to the heart, which will also lead to a heart attack in a baby. Coronary steal develops over time in babies with ALCAPA if the condition is not treated early.

Symptoms of anomalous left coronary artery in an infant include:

• Crying or sweating during feeding
• Pale skin
• Poor feeding
• Rapid breathing
• Sweating
• Symptoms of pain or distress in the baby (often mistaken for colic)

Symptoms can appear within the first 2 months of the baby's life.

ALCAPA can be diagnosed in an infant. However, this defect may not be diagnosed until someone is a child or adult.

Signs of anomalous left coronary artery include:

• Abnormal heart rhythm
• Enlarged heart
• Heart murmur (rare)
• Rapid pulse

Tests for anomalous left coronary artery include:

• A test of the electrical activity in the heart (electrocardiogram)
• A special dye injected into the blood vessels of the heart to see their structure and position (arteriography)
• A thin tube (catheter) inserted in a blood vessel of the heart to measure blood pressure and oxygen levels (cardiac catheterization)
• Cardiac magnetic resonance imaging (MRI)
• Chest x-rays
• Ultrasound of the heart (echocardiogram)

Surgery is needed to correct ALCAPA. Usually only one surgery is required, depending on the baby's condition and the size of the involved blood vessels.

If the mitral valve is seriously damaged from lack of oxygen, the baby may also need surgery to repair or replace the valve. The mitral valve regulates blood flow between the chambers on the left side of the heart.

If the baby's heart is already severely damaged from lack of oxygen, a heart transplant may be an option.

Very ill babies may need treatment with medications before surgery. The medications help the baby get strong enough to have surgery.

Medications include:

• "Water pills" (diuretics )
• Medications that make the heart muscle pump harder (inotropic agents)
• Medications that lower the work load on the heart (beta-blockers, ACE inhibitors)

See also: Congenital heart defect corrective surgery

Without treatment, most babies do not survive their first year. Those who survive without treatment are likely to have severe complications, or die suddenly during the following years.

With timely treatment, most babies do well and can expect a normal life. However, they need routine follow-ups with a heart specialist (cardiologist).

Complications of ALCAPA include:

• Heart attack
• Heart failure
• Heart rhythm problems
• Permanent damage to the heart
• Permanent damage to the mitral valve in the heart, requiring repair or replacement later in life

Call your health care provider if your baby:

• Is breathing rapidly
• Looks very pale
• Seems distressed and cries often

Other Congenital Heart and Vascular Malformations. In: Kliegman RM, Behrman RE, Jenson HB, et al., eds. Nelson Textbook of Pediatrics, 18th ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 432.

Marelli AJ. In: Mandell GL, Bennett JE, Dolin R. Goldman: Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 68.

Park MK. Park: Pediatric Cardiology for Practitioners, 5th ed. Philadelphia, PA: Mosby Elsevier; 2008.