What is Aortic Coarctation?
Coarctation of the aorta is a narrowing of the aorta. The aorta is the main blood vessel carrying oxygen-rich blood from the left ventricle of the heart to all the organs of the body.
Coarctation occurs most often in a short piece of the aorta just beyond where the arteries to the head and arms take off.
This portion of the aorta is called the "juxtaductal" aorta.
The ductus arteriosus is a blood vessel that is normally present in a fetus. It has special tissue in its wall that causes it to close in the first hours or days of life. Coarctation may be caused by having extra ductal tissue.
In babies with coarctation, the aortic arch may also be small (hypoplastic). Coarctation may also occur with other cardiac defects, typically involving the left side of the heart. The defects usually seen with coarctation are bicuspid aortic valve and ventricular septal defect. Coarctation may also be seen as a part of more complex, single ventricle heart defects.
Coarctation of the aorta is common in some patients with genetic disorders, such as Turner's syndrome.
When a coarctation exists, the left ventricle must work harder to create a higher pressure than normal to force blood through the narrow part of the aorta to the lower part of the body.
If the narrowing is very severe, the ventricle may not be strong enough to do this extra work. This can lead to congestive heart failure or not enough blood flow to the organs of the body.
Diagnosis of Coarctation
Coarctation of the aorta is present from birth. The age at which coarctation is found depends on the severity of the narrowing.
In about 25 percent of cases of isolated coarctation, the narrowing is severe enough to cause symptoms in the first days of life. When the ductus arteriosus closes, the left ventricle must suddenly pump against much higher resistance. This can lead to heart failure and shock. Because these newborns are well until the ductus arteriosus closes, symptoms appear quickly. They are often severe.
In patients who do not develop heart failure as newborns, coarctation may not be found until the child is several years old. In these older patients, coarctation is often first thought of because of a heart murmur or high blood pressure.
Coarctation is considered when the doctor is unable to feel pulses in a child’s legs. High blood pressure in the arms (but not the legs) may be noticed. A heart murmur is usually present. It may be loudest in the back. This is where the aorta is located.
The diagnosis of coarctation is confirmed with echocardiography. This can look at the anatomy of the aorta. It can also evaluate for other cardiac anomalies that may be present. Occasionally other tests, such as a cardiac MRI or CT scan, may be used to look at the coarctation.
In a critically ill newborn, the goals are to improve ventricular function and restore blood flow to the lower body. A continuous intravenous medication, prostaglandin (PGE-1), is used to open the ductus arteriosus. This allows blood flow to the body beyond the coarctation. Often other intravenous (IV) medicines may also be needed to help the heart. Many babies need to be placed on a ventilator before surgery.
If the baby has symptoms of a coarctation, surgery is done on an urgent basis.
There are a few surgical techniques to repair coarctation. The most common repair involves resection (removal) of the narrowed area with anastomosis (reconnection) of the two ends to each other. Sometimes the resection (removal) must be extended towards the arch if there is a longer piece of narrowing. In another method, the narrowing may be opened with a patch. Or a portion of an artery may be used as a flap to expand the area (called a subclavian flap aortoplasty).
Because older children may have minimal symptoms, coarctation repair is typically planned electively. Surgical repair is usually done with resection of the narrowed piece and end-to-end reconnection.
In older children, transcatheter therapy is the first-line therapy. It offers the ability to use a balloon or stent to dilate (make the area bigger) the area of narrowing without needing surgery. In children who are still growing, the placement of a stent means that an additional catheterization procedure is likely to be needed in the future.
Results of Treatment
To repair coarctation surgically, clamps must be placed on the aorta. This will quickly interrupt blood flow to downstream areas. Complications of surgery, are damage to organs such as the kidneys or the spinal cord. This is not common in children.
Return of coarctation at the site of surgical or balloon treatment is possible. This may even happen years later. The rate of restenosis is highest among newborns. This happens in 10-20 percent of patients. The rate of recurrent coarctation after surgical repair decreases in older children. The rate is close to zero by age 3 years. Some patients with recurrent coarctation may need repeat surgery. But, most cases can be managed with balloon dilation or stenting.
Another concern after coarctation repair is hypertension (high blood pressure). While this is rarely seen in infants, most older children have unusually high blood pressure right after surgery. This is treated with intravenous medicines. Children will often be sent home on medicine to treat high blood pressure.
Blood pressure will return to normal in many children (allowing medication to be stopped). Long-term or late hypertension may occur in some patients, needing long-term treatment.
Long-term follow-up with a cardiologist is important for children after coarctation treatment to diagnose late problems of restenosis or high blood pressure. Follow-up visits include a physical exam with blood pressure measurements in both the arms and legs. Periodic electrocardiograms and echocardiograms may also be needed. In older and larger patients, cardiac MRI or CT scans may be done to better look at the repaired aorta. Long-term cardiology follow-up is also important for any additional heart problems.
Adult and Adolescent Management
Most adults born with aortic coarctation will have been repaired in childhood. This repair may have been surgical or done in the cardiac catheterization laboratory using a balloon or stent. These patients need lifelong monitoring by a congenital heart specialist.
Narrowing of the aorta may recur or may not have been completely repaired at all. Secondly, aneurysms can form at the site of repair or in the aorta. MRI studies or CT studies need to be done to be sure aneurysms don’t exist. Third, patients who have had aortic coarctation repair have a high chance of high blood pressure that needs treatment. Sometimes the treatment is with medicines. Sometimes treatment is with a stent or other procedure. Next, patients who have a history of aortic coarctation usually have a bicuspid aortic valve. This valve may or may not breakdown over time. Patients who have such valves also tend to have aneurysms of their ascending aorta.
We expect patients with a repaired aortic coarctation to do well. But additional treatment of one form or another may be needed to protect their long-term health.