Overview of coarctation of the aorta
Coarctation of the aorta is a birth defect in which a part of the aorta is narrower than usual. If the narrowing is severe enough and if it is not diagnosed, the baby may have serious problems and may need surgery or other procedures soon after birth. For this reason, coarctation of the aorta is often considered a critical congenital heart defect. The defect occurs when a baby’s aorta does not form correctly as the baby grows and develops during pregnancy.
The narrowing of the aorta usually happens in the part of the blood vessel just after the arteries branch off to take blood to the head and arms, near the patent ductus arteriosus, although sometimes the narrowing occurs before or after the ductus arteriosus. In some babies with coarctation, it is thought that some tissue from the wall of ductus arteriosus blends into the tissue of the aorta. When the tissue tightens and allows the ductus arteriosus to close normally after birth, this extra tissue may also tighten and narrow the aorta.
The narrowing or coarctation blocks normal blood movement to the body. This can reverse flow into the heart’s left ventricle, making the muscles in this ventricle work harder to draw blood out of the heart. Since the narrowing of the aorta is usually localized after the arteries branch to the upper body, coarctation in this region can lead to normal or high blood pressure and blood pulses in the head and arms and low blood pressure.
If the condition is very severe, not enough blood may reach the lower body. The extra work on the heart can cause the walls of the heart to thicken to pump harder. This eventually weakens the heart muscle. If the aorta doesn’t widen, the heart can become weak enough to cause heart failure. Coarctation of the aorta often occurs with other inherited heart defects.
Causes of coarctation of the aorta
In most children, the cause isn’t known. Some children can have other heart defects along with coarctation.
How does it affect the heart?
The coarctation blocks blood flow from the heart to the lower body. Blood pressure rises above the constriction. Blood pressure is much higher than normal in the left pumping chamber (left ventricle), and the heart must work harder to pump blood through the constriction in the aorta. This can cause thickening (hypertrophy) and damage to the overloaded heart muscle.
Symptoms of coarctation of the aorta
Symptoms depend on the severity of the narrowing. Severe cases often are diagnosed at birth or within the first months of life. In mild cases, the individual may be symptom-free into adulthood. Symptoms in an adult may include exercise intolerance, headache, shortness of breath, chest pain, nose bleeds, cold feet or leg pain after exercise, or hard-to-control high blood pressure (hypertension).
Treatment for coarctation of the aorta
Most newborns with symptoms will have surgery right after birth or shortly thereafter. They will first receive medications to stabilize them.
Children who are diagnosed when they are older will also need surgery. In most cases, the symptoms are not as severe, so more time can be taken to plan for surgery.
During surgery, the narrow part of the aorta will be removed or opened.
- If the problem area is small, the two free ends of the aorta can be reconnected. This is called end-to-end anastomosis.
- If a large part of the aorta is removed, a graft or one of the patient’s own arteries can be used to fill the space. The implant can be artificial or from a cadaver.
Sometimes physicians will try to stretch and open the narrow part of the aorta using a balloon that extends into the blood vessel. This type of procedure is named balloon angioplasty. It can be done in place of surgery but has a higher failure rate.
Older children generally need medicine to treat high blood pressure after surgery. Some will need lifelong treatment for this problem.
Diagnosis of coarctation
Coarctation of the aorta is present from birth. The age at which coarctation is detected depends on the severity of the narrowing.
In approximately 25 per cent of cases of isolated coarctation, the narrowing is severe enough to cause symptoms in the first days of life when the ductus arteriosus closes. When the ductus arteriosus closes, the left ventricle must suddenly pump against much higher resistance and this can lead to heart failure and shock. Because these newborns are well until the ductus arteriosus closes, symptoms appear rapidly and are often severe.
In patients who don’t develop heart failure as newborns, coarctation may not be detected until the child is several years old. In these older patients, coarctation is often first suspected because of a heart murmur or high blood pressure.
Coarctation is suspected when the physician is unable to feel pulses in a child’s legs. High blood pressure in the arms (but not the legs) may be detected. A heart murmur is usually present and maybe loudest in the back (where the aorta is located).
The diagnosis of coarctation is usually confirmed with echocardiography, which can define the anatomy of the aorta and evaluate for other cardiac anomalies that may also be present. Occasionally other tests, such as a cardiac MRI or CT scan, may be used to document the presence of a coarctation.
Coarctation of the aorta risk factors
Coarctation of the aorta often occurs along with other congenital heart defects. Certain heart conditions are often associated with coarctation, including:
- Bicuspid aortic valve. The aortic valve separates the lower left chamber (left ventricle) of the heart from the aorta. A bicuspid aortic valve has two flaps (cusps) instead of the usual three. Many people with coarctation of the aorta have a bicuspid aortic valve.
- Sub-aortic stenosis. Sub-aortic stenosis occurs when there is a narrowing of the area below the aortic valve that obstructs blood flow from the left ventricle to the aorta. This narrowing may be in the form of a fibrous membrane.
- Patent ductus arteriosus. The ductus arteriosus is a blood vessel that connects a baby’s left pulmonary artery to the aorta. It allows blood to bypass the lungs while the baby is growing in the womb. Shortly after birth, the ductus arteriosus usually closes. If it remains open, it’s called a patent ductus arteriosus.
- Holes in the wall between the left and right sides of the heart. Some people are born with a hole in the wall (septum) between the upper heart chambers (atrial septal defect) or the lower heart chambers (ventricular septal defect). This causes oxygen-rich blood from the left side of the heart to mix with oxygen-poor blood in the right side of the heart.
- Congenital mitral valve stenosis. The mitral valve is between the upper and lower left heart chambers. It lets blood flow through the left side of your heart. In mitral valve stenosis, the valve is narrowed. As a result, the movement of blood between the upper and lower left heart chambers is reduced, increasing the pressure in the upper left chamber (atrium). The oxygen-rich blood from the lungs returns to the heart through veins that attach to the upper left chamber. Increased pressure in the left atrium may result in symptoms of lung congestion. These symptoms include shortness of breath, difficulty breathing during exercise and shortness of breath when lying flat.
Without treatment, coarctation of the aorta frequently leads to complications. In babies, it may lead to heart failure or death.
High blood pressure is the most common long-term complication of coarctation of the aorta. Blood pressure usually drops after the aortic coarctation has been repaired, but may still be higher than normal.
Other complications of coarctation of the aorta may include:
- A weakened or bulging artery in the brain.
- Aortic rupture or tear (dissection).
- Enlargement in a section of the wall of the aorta.
- Heart failure
- Premature coronary artery disease.
Coarctation of the aorta cannot be prevented because it is usually present at birth. However, if you or your child have a condition that increases the risk of aortic coarctation, such as Turner syndrome, bicuspid aortic valve, or another heart defect, or a family history of congenital heart disease, early uncovering can help. Deliberate the risk of aortic coarctation with your doctor.