Aortic Stenosis

Aortic Stenosis is a condition that causes a blockage in the flow of blood between the left ventricle and the aorta. The obstruction can be below the aortic valve, at the valve itself, or just above the valve. The most common type of aortic stenosis is obstruction at the valve itself.

Anatomy/Causes

It is important to describe a normal valve first. The normal aortic valve has three thin, flexible leaflets. When the left ventricle pumps blood into the aorta to go out to the rest of the body, the normal aortic valve leaflets spread apart easily and cause no obstruction to the flow of blood out of the heart. In aortic stenosis, the leaflets of the valve are not formed correctly. The most common defect is when the valve has only two leaflets instead of three. This is called a bicuspid valve. It is a congenital defect. These two leaflets are often thickened and not as flexible as they should be. This causes the left ventricle of the heart to work harder to push the blood out of the aorta to the rest of the body. This extra work put on the left ventricle causes the muscle tissue of the left ventricle to get thicker. This is called left ventricular hypertrophy or LVH. If the obstruction of the aortic valve is severe, the left ventricle may not be able to work hard enough and it begins to fail. Fortunately, this is rare, but when it happens, the child goes into heart failure.

Signs/Symptoms

Kids with this defect are often healthy and have no symptoms. The most common indication that there is a problem is when a pediatrician hears a murmur, a “whooshing” sound heard with a stethoscope. If the stenosis is mild to moderate, a murmur will be heard easily. Later in childhood, kids may develop exercise intolerance, labored breathing and fainting upon exertion. If the stenosis is severe, it is an emergent situation. This happens in a newborn on the first day of life and requires immediate treatment since the infant is in heart failure. Older children rarely experience heart failure, but they may have chest pain, fainting spells or dizziness, especially when they exercise. An older child with undiagnosed severe aortic stenosis is at high risk of sudden death during strenuous activities such as sports.

Diagnostic Tests

  • Electrocardiogram (EKG) – records the electrical activity of the heart. It is usually normal in mild to moderate stenosis. If there is severe stenosis, it can show left ventricular enlargement.
  • Echocardiogram (Echo) – similar to an ultrasound; uses sound waves to bounce off the structures of the heart and produces a picture of the heart; shows the volume and direction of flow through the heart itself. It can accurately show the obstruction itself and how severe it is. This is the gold standard for diagnosis of aortic stenosis.
  • Stress Test – Attached to monitors and in the presence of a physician, the child runs on a treadmill while being closely observed for abnormal blood pressure and heart function in response to exercise. The results may help the doctor decide if treatment is needed.
  • Cardiac Catheterization (Heart Cath) – provides information about the heart’s structures, pressure measurements above and below the valve to determine the degree of valve obstruction, and oxygen levels within the heart itself.

Treatment

In kids with mild aortic stenosis, treatment is rarely required. Unfortunately, this can be progressive over time and these kids may eventually require treatment. Therefore, it is important that they be followed closely by a cardiologist.

Treatment itself is determined by the degree of stenosis and its location. For mild valvular stenosis, kids are typically managed with diuretics, antibiotics (to prevent infection in the heart) before any routine dental or surgical procedure, and exercise restriction.

Moderate to severe aortic stenosis requires intervention. Balloon dilation valvuloplasty, performed in the Cath Lab, is the first-line procedure. This is not open heart surgery, is done via the femoral artery in the groin, and generally requires only an overnight stay in the hospital. It can also be done as an outpatient in older children. If open heart surgery is necessary, the surgeon will perform a valvotomy where the stiff and malformed valve is opened. This is only done when the valve cannot be improved with simple balloon dilation. In some more complicated valve issues, the aortic valve may need to be completely replaced. This is called a Ross Procedure and with it, the patient’s own pulmonary valve is transplanted to the aortic valve position. The pulmonary valve is then replaced with a homograft (human donor graft) from the right ventricle to the pulmonary artery. This is a wonderful option for younger children since the newly replaced aortic valve can continue to grow with the child. This prevents more frequent surgeries to replace a valve that the child has outgrown and also does not require that the child take blood thinner medication. However, it will require eventual replacement of the pulmonary valve homograft.

There is another surgical procedure that may be necessary if the aortic valve is too small. The Konno procedure is a technique to enlarge the area where a new valve needs to be placed. This new valve is called a “mechanical valve” because it is not made from the patient’s own tissue. This will require that the patient be on blood thinner medication along with regular blood tests to monitor blood levels of the medication, usually Coumadin. A mechanical “click” sound of this valve can be heard with a stethoscope.

Prognosis

Balloon dilation valvuloplasty has shown excellent results, even though it causes mild valve insufficiency or leakage. This generally does not cause problems; however, recurrent narrowing does occur in many children within the next 5-10 years after the procedure. Many of these children will require repeat balloon dilation or surgical valve replacement.

Results of these open heart surgical procedures have also been excellent as they relieve all aortic stenosis with low complication rates. If an adult-sized artificial aortic valve is implanted in larger children or adolescents, they should see excellent function for 20 years or more. If the replacement of the valve is done as a younger child, the concern is that the child will outgrow the size of the artificial valve, and repeat surgical replacement will be needed in later years.

All treatments for aortic stenosis are palliative not a cure. Long-term follow-up with a cardiologist is essential for helping to provide the best outcome for these patients.