Coarctation of the aorta (COA)

At Boston Children's Hospital, we know that the first step to restoring your child’s health is to form an accurate and timely diagnosis.

Diagnosing the infant

Your child's doctor may have heard a heart murmur (a noise caused by the turbulence of blood flowing through a narrow region) during a physical exam and referred your child to a pediatric cardiologist* for a diagnosis. The murmur can—but doesn’t usually—result from the coarctation itself; more often, the murmur is the result of secondary defects, such as a bicuspid aortic valve or a VSD.

*A pediatric cardiologist specializes in the diagnosis and medical management of congenital heart defects—as well as any heart problems that may develop later in childhood.

The first line of diagnosis for COA is the clinical exam, beginning with obtaining the child’s vital signs. The pediatric cardiologist obtains a four-limb blood pressure—measuring the blood pressure in both arms and both legs.

The doctor may suspect a coarctation if the blood pressure in the child’s legs is lower than the pressure in his arms. The baby’s femoral (thigh) or foot pulses will be weak and therefore very difficult for the doctor to feel. (Part of the newborn discharge exam is to be able to feel four good pulses.)

Other tests that help with the diagnosis—or with treatment planning—may include:

• echocardiogram (echo, cardiac ultrasound): evaluates the structure and function of the heart by using sound waves, recorded on an electronic sensor, that produce a moving picture of the heart and heart valves. At Children’s, the echocardiogram is the primary diagnostic tool to confirm a diagnosis of COA, especially in young children.

A tiny patient gets an ultrasound at Children’s

• electrocardiogram (ECG or EKG): records the electrical activity of the heart, shows abnormal rhythms (arrhythmias or dysrhythmias) and detects heart muscle damage.
• cardiovascular MRI (magnetic resonance imaging): a diagnostic procedure that uses a combination of large magnets, radiofrequencies and a computer to produce detailed images of organs and structures within the body.
• chest x-ray: a diagnostic test that uses invisible electromagnetic energy beams to produce images of internal tissues, bones and organs onto film. At Children’s, x-ray is used to diagnose COA only occasionally.

A word about prenatal diagnosis

COA can sometimes be detected prenatally through cardiac ultrasound: The test can pick up the size discrepancy between the left heart and the right heart, as well as the narrowing of the aortic arch. The aortic arch may not be obstructed in the fetus because of the ductus arteriosus, which is open (patent) in the fetus. But the obstruction can show up in the newborn after his ductus arteriosus closes.

So, while knowing in advance that the newborn will have COA can help doctors and families to be prepared for treatment after birth, there’s really no need to treat the fetus in utero.

Diagnosing the older child, teen or adult

Mild or moderate cases of COA may not be diagnosed until school-age, adolescence or even adulthood—whenever symptoms appear (sometimes it’s detected because of elevation on routine blood pressure measurement). As a child with COA grows, his aorta will not grow at the same rate; so with a relative narrowing later in life, signs and symptoms can appear, such as:

• high blood pressure
• nosebleeds
• a heart murmur
• headaches (from high blood pressure above the COA)
• cramps in the lower sections of the body (from low blood pressure below the COA)

With the onset of symptoms, cardiologists will diagnose COA through physical examination and the use of advanced diagnostic tools.