Pediatric Heart Disease Aortic Stenosis

Aortic stenosis refers any condition that prevents the flow of blood from the heart’s left ventricle to the aorta, the major artery responsible for moving oxygenated blood to the body. As one of the more common heart valve defects, aortic stenosis affects five out of every 10,000 Americans. Without treatment, aortic stenosis can cause serious health complications.

Causes of Aortic Stenosis

Stenosis is a medical term meaning “narrowing” Consequently, aortic stenosis means the aortic valve is too narrow to allow normal blood flow from the heart’s left ventricle to the aorta. Often, aortic stenosis is caused by congenital heart defects (heart problems present from birth).

A healthy aortic valve has three flaps, referred to as leaflets or cusps. When infants are born with less than three aortic valve flaps, they suffer from aortic stenosis. While the presence of one flap is known as a unicuspid aortic valve, doctors refer to two flaps as a bicuspid aortic valve. Unicuspid and bicuspid valve flaps tend to be thicker and stiffer than regular aortic valve leaflets. Because these thicker leaflets interfere with how well the aortic valve opens and closes, less blood gets to the aorta and, therefore, the rest of the body.

Other causes of aortic stenosis include natural aging and childhood rheumatic fever. Additionally, some infants may suffer from aortic stenosis if they are born with aortic valves that are simply too narrow. However, this is one of the most rare causes of aortic stenosis.

Symptoms of Aortic Stenosis

Most children with aortic stenosis have an asymptomatic condition, meaning the condition exists without any identifiable symptoms. Unfortunately, symptoms only occur in the most severe cases of aortic stenosis. An infant born with severe aortic stenosis will require emergency treatment, as heart failure can occur within days of birth.

In older children, aortic stenosis symptoms are often associated with exercise and physical activity. During or after exercise, a child with aortic stenosis may experience:

  • chest pain
  • chest tightness
  • dizziness or lightheadedness
  • fainting
  • fatigue
  • shortness of breath.

Aortic Stenosis and Sudden Death

In rare cases, intense physical activity combined with severe aortic stenosis has resulted in sudden death. An example might be the high school football player who suddenly collapses on the field. While such events do occur, keep in mind that sudden death due to aortic stenosis is extremely rare.

Diagnosing Aortic Stenosis

Here are some of the common ways doctors diagnose aortic stenosis:

  • At a routine physical: As most cases of aortic stenosis are asymptomatic, this condition is usually detected during routine physical examinations. During a child’s physical, the doctor may detect a heart murmur, an unusual noise caused by a heart defect.The heart murmur associated with aortic stenosis has a characteristic sound that ends with a clicking noise as the aortic valve opens. The presence of a heart murmur demands further investigation to confirm or rule out heart problems.
  • Through a cardiac catheterization: Although use of an echocardiogram is more common, a cardiac catheterization may also be used to diagnose aortic stenosis. During cardiac catheterization, a thin tube, or catheter, is inserted into an artery in the arm or groin. The catheter is then threaded through the arteries to the heart. Once in the heart, the catheter injects a dye into the blood so blood flow in the heart can be X-rayed. A cardiac catheterization can detect the arterial obstructions that are often associated with aortic stenosis. Cardiac catheterization can also measure blood pressure in the left ventricle and display video images of the aortic valve opening and closing.
  • Through a chest X-ray: Standard X-rays of the chest can highlight if the heart is enlarged or if excessive blood is being pumped to the heart, which are both indications of the presence of aortic stenosis.
  • Through an ECG: Also known as an electrocardiogram, an ECG is often used to diagnose aortic stenosis. During an electrocardiogram, electrodes attached to the skin record the heart’s electric impulses. While mild to moderate aortic stenosis usually yields normal electrocardiogram results, severe aortic stenosis will cause abnormal results on an ECG. An ECG can also provide evidence that the left ventricle is enlarged, a common complication of aortic stenosis.
  • Through an echocardiogram: While an electrocardiogram detects impulses by monitoring electric energy, an echocardiogram uses sound waves to construct an image of the heart, allowing cardiologists to see aortic valve abnormalities.

Aortic Stenosis Treatment

Asymptomatic aortic stenosis rarely requires treatment during childhood. However, because aortic stenosis symptoms can worsen as the child ages, a pediatric cardiologist should monitor asymptomatic aortic stenosis cases as well.

No treatment can cure aortic stenosis. Instead, treatment seeks to prevent aortic stenosis complications and alleviate existing symptoms. The four treatment options currently available for aortic stenosis are:

  • balloon dilation valvuloplasty
  • surgical valvotomy
  • the Konno procedure
  • the Ross procedure.

Balloon Dilation and Cardiac Catheterization

Balloon dilation valvuloplasty is performed using cardiac catheterization techniques. The catheter positions a small balloon in the aortic valve. As the balloon inflates, it widens the aortic valve.

Vein choice for cardiac catheterization depends on the age of the patient. In most children, balloon dilation procedures use the femoral artery (the main artery of the thigh) for cardiac catheterization. In newborns, cardiac catheterization uses the umbilical artery (the artery attached to the umbilical cord) to prevent damage to delicate newborn arteries.

Although hospitalization is usually required for observation, doctors can perform balloon dilation on an outpatient basis. Yet, while this procedure improves aortic stenosis symptoms, it is not a permanent solution. Many children require additional treatment within 10 years of undergoing balloon dilation valvuloplasty.

The main complication associated with balloon dilation is aortic insufficiency, marked by blood leaking back into the left ventricle. While aortic insufficiency causes minimal leakage in most patients, between 3 percent and 5 percent of patients develop severe aortic insufficiency and require additional treatment.

Surgical Valvotomy

Surgical valvotomy is an open-heart surgical treatment for aortic stenosis. Although a surgical valvotomy is invasive and less common since the development of balloon dilation, balloon treatments are not effective for all cases of aortic stenosis. If aortic stenosis results from calcium deposits on aortic valve cusps, fused valve leaflets or undersized valve rings, surgical valvotomy is required.

Barring co-morbid diseases (diseases that occur simultaneously with aortic stenosis), surgical valvotomy outcomes are generally positive. Like with balloon dilation, surgical valvotomy generally causes aortic stenosis to recur within 10 years of surgery.

The Konno Procedure

The Konno procedure is a treatment method that requires surgeons to make an incision in a small aortic valve ring to enlarge the valve. The valve can then be replaced with a mechanical or natural valve. If a natural valve is used, the treatment is called a Ross-Konno procedure.

The Ross Procedure

Sometimes aortic stenosis is severe enough that the aortic valve must be replaced. If replaced with a mechanical valve, the patient requires lifelong anticoagulation therapy to avoid blood clots from forming and obstructing blood flow. An adult-sized artificial valve lasts up to 20 years if implanted during adolescence. Artificial valves implanted in younger patients may need to be replaced as the child grows.

However, implanting artificial valves is not the only surgical option: Organic material from the child’s own body may be used to treat aortic stenosis. The Ross procedure is an open-heart aortic stenosis treatment that avoids the use of artificial valves. The defective aortic valve is replaced with the child’s own pulmonary valve, which is in turn replaced with a valve from a human donor.

The Ross procedure is recommended for cases of aortic stenosis in young patients, female patients who have started ovulating and patients with left ventricular outflow blockage.

Aortic Stenosis and Endocarditis

Children living with aortic stenosis have an increased risk of developing heart infections (known as endocarditis) both before and after aortic stenosis treatment. Preventative antibiotics are required prior to dental work and surgery to lower the risk of endocarditis. Good oral hygiene also lowers the risk of endocarditis infection.

Monitoring Aortic Stenosis

Children with aortic stenosis require periodic checkups with cardiologists throughout their lives. Because aortic stenosis treatments do not completely restore valve function, they may require repeated treatments over time. To limit the possibility of complications, cardiologists can also recommend limiting physical activity and exercise.

Resources

American Heart Association (2007). Aortic stenosis. (AS). Retrieved September 4, 2007, from the AHA Web site: www.americanheart.org/presenter.jhtml?identifier=1659.

Cincinnati Children’s Hospital Medical Center (2006). Aortic stenosis. Retrieved September 4, 2007, from the Cincinnati Children’s Hospital Medical Center Web site: www.cincinnatichildrens.org/health/heart-encyclopedia/anomalies/avs.htm.

Mayo Foundation for Medical Education and Research (2007). Aortic valve stenosis. Retrieved September 4, 2007, from the Mayo Clinic Web site: www.mayoclinic.com/invoke.cfm?id=DS00418.

U.S. National Library of Medicine (2007). Aortic stenosis. Retrieved September 4, 2007, from the Medline Plus Web site: www.nlm.nih.gov/medlineplus/ency/article/000178.htm.