Pediatric Heart Disease Pulmonary Stenosis

Pulmonary stenosis occurs when blood moving from the right ventricle to the pulmonary artery is obstructed. The pulmonary artery delivers oxygen-depleted blood to the lungs, where the blood is re-oxygenated. Pulmonary stenosis requires the right ventricle to work harder to pump blood through the pulmonary valve to get oxygen.

If pulmonary stenosis results in insufficient blood flow to the lungs, cyanosis can develop. Cyanosis causes the lips and fingernail beds to appear bluish. Pulmonary stenosis occurs in 10 percent of congenital heart defects (heart defects that people are born with), either alone or co-morbid (in combination) with other heart defects.

Pulmonary Stenosis Causes

Stenosis, the medical term meaning “narrowing,” typically occurs in the pulmonary artery due to congenital abnormalities (i.e., birth defects). Normally, the pulmonary valve contains three flaps, or leaflets, that open as blood flows from the right ventricle into the pulmonary artery. Birth defects may result in thick, inflexible valve flaps that may even be fused together. Thickened, fused flaps impair blood flow and cause pulmonary stenosis.

Other possible causes of pulmonary stenosis include abnormally small pulmonary valve rings, thick muscle around the pulmonary valve or an abnormally narrow pulmonary artery. No matter what the cause, the result of pulmonary stenosis is the same: The heart must work harder to pump blood to the lungs.

Pulmonary Stenosis Symptoms

Because cases of pulmonary stenosis are generally asymptomatic, children with mild forms of this condition don’t usually experience any noticeable symptoms. Most children with mild pulmonary stenosis grow at normal rates and can engage in physical activity without fear of symptom onset.

However, in some pulmonary stenosis cases, patients may experience the following symptoms:

  • chest pain
  • cyanosis (described in more detail below)
  • failure to thrive
  • fainting
  • fatigue
  • poor weight gain
  • shortness of breath
  • sudden death.

Although rare, severe pulmonary stenosis can cause right ventricular failure and sudden death in older children and adolescents. In such cases, the trigger may be physical overexertion. Consequently, children with moderate to severe pulmonary stenosis should talk to their doctors about appropriate exercises, as well as what types of physical activities they should avoid.

Cyanosis and Pulmonary Stenosis Symptoms

Severe pulmonary stenosis can cause cyanosis, indicating that blood (and, therefore, the rest of the body) isn’t getting enough oxygen. Cyanotic symptoms include blue lips and fingernail beds. Newborns with severe pulmonary stenosis may not develop cyanosis until a few days after birth.

The severity of cyanosis can increase when oxygen-rich and oxygen-poor blood are mixed and circulated throughout the body. Keep in mind that all newborns are born with a temporary opening between the left and right atria (the heart’s upper chambers) called the foramen ovale. If severe pulmonary stenosis prevents the right ventricle from pumping sufficient blood to the lungs, the blood “backs up” into the right atria.

Oxygen-depleted blood in the right atria then flows through the foramen ovale into the left atria, where it mixes with oxygen-rich blood. The mixture of oxygen-rich and oxygen-poor blood is then pumped to the body, increasing the presence of cyanotic symptoms.

Diagnosing Pulmonary Stenosis

The lack of symptoms associated with pulmonary stenosis means the condition can go undetected unless blood flow restrictions cause cyanosis.

Often, the presence of pulmonary stenosis is only detected when an examining doctor detects a heart murmur during a child’s physical examination. A heart murmur is a noise heard during the heartbeat when obstructions or heart valve defects are causing irregular beats. Heart murmurs associated with pulmonary stenosis include a click when the deformed valves shut.

Once a doctor detects a heart murmur, he will call for more diagnostic tests to evaluate whether or not pulmonary stenosis is present. These tests include:

  • Cardiac catheterization: Because cardiac catheterizations are more invasive than other diagnostic tools, they have largely been replaced by the echocardiogram. During cardiac catheterization, a thin tube (or catheter) is inserted into a blood vessel in the arm or groin. The catheter is then threaded through the blood vessels to the right ventricle, where it releases a dye that is tracked through X-rays. The X-rays reveal the path of the blood, indicating the obstruction’s location.
  • Echocardiogram: This is one of the most accurate diagnostic tests for pulmonary stenosis. An echocardiogram uses sound waves to produce an image of the heart. By examining echocardiogram results, doctors can look for pulmonary valve obstructions, as well as defects in the valve’s structure.
  • Electrocardiogram: Known for short as an ECG, an electrocardiogram calls for doctors to attach electrodes to the skin to measure the heart’s electric impulses. While electrocardiograms may not be able to detect mild pulmonary stenosis, they can provide evidence of an enlarged right ventricle in more severe cases pulmonary stenosis.

Treating Pulmonary Stenosis

Treatment of pulmonary stenosis depends on the age of the child and the severity of pulmonary stenosis symptoms. Mild pulmonary stenosis does not interfere with a child’s life and rarely worsens after the first year of life.

Newborns with severe pulmonary stenosis and signs of cyanosis require emergency treatment. However, treatment is complicated by the fact that cyanotic newborns are often already extremely ill. In older children, moderate to severe pulmonary stenosis can be treated in a few different ways, including:

  • balloon dilation valvuloplasty
  • open-heart surgery.

Balloon Dilation Valvuloplasty

Balloon dilation valvuloplasty uses cardiac catheterization to position a small balloon in the pulmonary valve. When the balloon inflates, it stretches the valve open to allow more blood to enter the atrium. Although balloon dilation valvuloplasty does not cure pulmonary stenosis, the procedure reduces blood obstructions, turning severe pulmonary stenosis into a mild case.

Although balloon dilation usually needs to be performed only once in older patients, about 20 percent of infant cases will require additional balloon dilation treatments due to pulmonary stenosis recurrence.

Pulmonary Stenosis and Open Heart Surgery

While most cases of pulmonary stenosis respond well to balloon dilation, open-heart surgery is necessary when the pulmonary valve is abnormally small or in cases when valve leaflets are extremely thick. Like balloon dilation valvuloplasty, open-heart surgery outcomes are usually positive and don’t normally require further surgery.

Monitoring Pulmonary Stenosis

No matter how successful pulmonary stenosis treatment is, regular check-ups by a pediatric cardiologist are required after treatment to help ensure the best possible outcome.

Both before and after surgery, children with pulmonary stenosis are at higher than normal risk of contracting endocarditis, an infection of the heart muscle. To lower the risk of endocarditis, preventative antibiotics are prescribed before dental work and other surgeries. Proper dental hygiene can help lower the possibility that a patient will develop endocarditis.

Resources

American Heart Association (2007). Pulmonary stenosis. Retrieved September 4, 2007, from the AHA Web site: http://www.americanheart.org/presenter.jhtml?identifier=1321.

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

Tanser, Paul H., M.D. (2006). Pulmonary stenosis. Retrieved September 4, 2007, from the Merck Web site: www.merck.com/mmhe/sec03/ch028/ch028i.html.

U.S National Library of Medicine (2007). Pulmonary valve stenosis. Retrieved September 4, 2007, from the Medlineplus Web site:www.nlm.nih.gov/medlineplus/ency/article/001096.htm.