Myocardial Blood Flow in Children with AAOCA

Anomalous aortic origin of a coronary artery (AAOCA) is a rare congenital abnormality. AAOCA is associated with an increased risk of decreased blood flow to the heart tissue (called ischemia) and sudden death in otherwise healthy children and young adults. The risk of sudden death is greatest during or just after exercise.

Children’s Hospital researchers hypothesize that there is a decreased amount of blood flow to the region of the heart that is supplied by the anomalous coronary artery, caused by a narrowing at the opening of the coronary artery. To compensate for this narrowing, the portion of the vessel farther away from the opening is maximally or near-maximally enlarged (dilated) at rest.

During exercise, further coronary artery dilation is necessary to provide enough blood flow to the exercising heart muscle. Children with AAOCA may experience ischemia and sudden death, usually with exercise, because the already-dilated anomalous vessel cannot open further during exercise.

Understanding the cause of ischemia in AAOCA

Julie Brothers, MD, is conducting a study using positron emission tomography (PET). Researchers use PET to measure the blood flow to different regions of the heart. Their goal is to better understand the cause of ischemia in AAOCA, and therefore the risk factors that cause some children with AAOCA to suffer ischemia while others remain healthy. With better knowledge of which children are at more risk, treatment could be better tailored to each individual child’s needs.

The study should also help determine the long-term results of surgery for AAOCA, which enlarges the opening of the coronary artery to increase blood flow. Given that ischemia most commonly occurs during or after exercise, Dr. Brothers also hopes to study the relationship between exercise performance and abnormalities in blood flow.

No studies to date have utilized PET to evaluate blood flow to the heart muscle in children with AAOCA. Dr. Brothers’ ability to conduct this groundbreaking study was made possible by a generous gift from Valerie B. Bowman and additional support from other donors to the Cardiac Center.

Reviewed on April 03, 2014