OVERVIEW: What every practitioner needs to know

Are you sure your patient has pulmonic stenosis? What are the typical findings for this disease?

Pulmonic stenosis can present in many ways depending on disease severity, but the majority of patients are asymptomatic.

  • The most common finding is a systolic murmur on routine exam.

  • Dyspnea on exertion or fatigue

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  • Cyanosis (if an atrial communication is present)

What other disease/condition shares some of these symptoms?

Tetralogy of Fallot

Ventricular septal defect

Atrial septal defect

Pulmonary atresia

Ebstein’s anomaly of the tricuspid valve

What caused this disease to develop at this time?

Pulmonic stenosis is a congenital heart defect; it is therefore present at birth. The exact cause of this defect in embryologic heart development is not understood, and the majority of cases are sporadic. There is an association with certain genetic syndromes, such as Noonan syndrome. While isolated pulmonic valve disease represents about 8%-10% of all congenital heart defects, about 25%-30% of patients with congenital heart disease have some additional type of right ventricular outflow obstruction, either below, above, or both below and above the pulmonary valve.

The severity of disease will determine when the patient presents clinically. Mild pulmonic stenosis will be asymptomatic, and will present at routine physical examination with a systolic ejection murmur. Moderate-to-severe stenosis, if not detected by routine clinical visits, will eventually present in later childhood and adulthood with dyspnea on exertion or fatigue. If an atrial communication is present, the patient may be mildly cyanotic. Critical stenosis presents shortly after birth with severe cyanosis.

What laboratory studies should you request to help confirm the diagnosis? How should you interpret the results?

An ECG can help identify the presence of right ventricular hypertrophy or right axis deviation associated with pulmonic stenosis; however, 40%-50% of patients have a normal ECG, especially if stenosis is mild.

Oxygen saturation measurement can help detect mild cyanosis.

Would imaging studies be helpful? If so, which ones?

Echocardiography is the best study to diagnose pulmonic stenosis. It is able to show the exact anatomy of the disease, as well as severity. It is non-invasive and easily obtained at the bedside or in a cardiology outpatient clinic.

Pulmonic stenosis is typically categorized into mild, moderate, and severe stenosis. Initial severity is defined by echocardiogram (Table I), but if intervention in the catheterization lab is warranted, severity is confirmed by direct pressure measurements with catheters.

Table I.
Severity Grade Pressure Gradient RV Pressure/LV Pressure Ratio
Mild <35-40 mmHg <50%
Moderate 40-60 mmHg 50%-75%
Severe >60 mmHg >75%

Confirming the diagnosis

Since most patients with pulmonic stenosis are asymptomatic, suspicion of the disease is usually obtained by hearing a cardiac murmur on physical exam. The standard accepted method of definitively confirming the diagnosis is the echocardiogram.

If you are able to confirm that the patient has pulmonic stenosis, what treatment should be initiated?

If the patient is a neonate and is diagnosed with critical pulmonic stenosis, immediate treatment is warranted. Initially, the patient can be stabilized by starting prostaglandin (PGE) therapy with a goal of maintaining pulmonary blood flow through the ductus arteriosus.

The two definitive options for treatment are catheter-based balloon pulmonary valvuloplasty and surgical pulmonary valvotomy (Table II).

Table II.
  Advantages Disadvantages
Catheter-based BalloonPulmonic Valvuloplasty Less invasive than surgeryExcellent results when pulmonary valve leaflets are thinShorter inpatient recoveryNo sternotomy needed Can result in pulmonic insufficiencyPoorer results with thickened, dysplastic leaflets 
Surgical PulmonicValvotomy More precise repair of pulmonary valve than balloonAbility to repair sub-valvar and supra-valvar obstructionPreferred option for thickened, dysplastic pulmonary valve leafletsPulmonary valve replacement available at the time of treatment Midline sternotomy requiredLonger inpatient recovery period

If the patient is past the neonatal period and is found to have severe pulmonic stenosis, the patient should undergo urgent or semi-urgent treatment, depending on clinical status. In addition, if there is suspicion of other associated non-cardiac abnormalities, a genetic evaluation would be appropriate.

Many patients with mild-to-moderate pulmonic stenosis do not require treatment, but rather, continued monitoring as an outpatient with serial echocardiography. The purpose of continued evaluation is to monitor for progression (or regression) of the stenosis, as well as for development of pulmonic insufficiency or right ventricular hypertrophy.

Antibiotic prophylaxis to prevent bacterial endocarditis is not recommended for pulmonic stenosis.

What are the adverse effects associated with each treatment option?

The goal of therapy, whether by catheter or surgery, is to balance the need to relieve enough of the obstruction to improve flow across the pulmonic valve, while not being so aggressive as to cause significant regurgitation. The main adverse effects of each option is either insufficient relief of obstruction or development of excessive regurgitation.

What are the possible outcomes of pulmonic stenosis?

Mild-pulmonic stenosis has a generally favorable prognosis. Many times, the stenosis will improve or go away completely over the first few years of life. For patients who have moderate or worse stenosis, treatment is usually needed eventually, and prognosis will depend on the immediate results of the procedure. Fortunately, the results of either catheter or surgical intervention are typically excellent, and often a single intervention is all that is needed over the patient’s lifetime.

The risks of treatment, as outlined earlier in the section, are typically minimal, and patients are usually able to have a full recovery from the treatment. In cases of dysplastic valves or the development of significant regurgitation, pulmonary valve replacement is sometimes needed. This must initially be a surgical pulmonary valve replacement (PVR), typically with a bioprosthetic valve. Since the bioprosthetic valve is not living tissue it will not grow, and will calcify over time, necessitating a lifetime of serial pulmonary valve replacements. Recently, there has been development of FDA approved transcatheter pulmonary valves, which may greatly reduce recovery time. These valves must be placed inside a pre-existing surgical conduit; therefore, they are only able to be used after initial surgical PVR. Fortunately, when considering all cases of pulmonic stenosis, initial intervention resulting in clinically significant pulmonary regurgitation is rare.

What causes this disease and how frequent is it?

The incidence of pulmonary valve stenosis is about 8%-10% of congenital heart defects, or approximately 8 in 10,000 live births. There is no known seasonal variation. Pulmonic stenosis is a congenital heart defect that is always present (although not always detected) at birth.

There is no known environmental exposure that causes development of pulmonic stenosis in the fetus.

There is a known association of pulmonic stenosis with certain genetic syndromes, such as Noonan syndrome. Williams syndrome and Alagille syndrome are both associated with branch pulmonary artery stenosis.

How do these pathogens/genes/exposures cause the disease?

The mechanism is unknown.

Other clinical manifestations that might help with diagnosis and management

In cases of mild or moderate pulmonic stenosis, the patient is typically asymptomatic. It has been shown that progression of pulmonic stenosis tends to occur during periods of rapid growth. Therefore it is recommended that patients be followed more closely during the first year of life and again during adolescence. If a patient has been shown to have stable mild pulmonic stenosis over several clinic visits, the patient may be followed less often (every 1-2 years).

What complications might you expect from the disease or treatment of the disease?

Complications are dependent on the severity of the obstruction. Possible outcomes include the development of right ventricular hypertrophy, right ventricular dilation and failure, the development of cyanosis (if an atrial communication is present), exercise intolerance, and reduced cardiac output. Delay of treatment into adulthood can result in irreversible myocardial fibrosis.

Two main complications can result from treatment of pulmonic stenosis: insufficient relief of obstruction or significant valvular insufficiency. Commonly accepted practices for valvuloplasty or valvotomy minimize the incidence of these complications. In general, the interventionalist chooses how aggressively to treat based on trying to balance obtaining sufficient relief of obstruction without causing significant insufficiency.

A promising new development in the treatment of pulmonic insufficiency is transcatheter pulmonary valve delivery, a procedure done in the catheterization lab that delivers a competent pulmonary valve percutaneously. This technique is still relatively new, but short- and medium-term results have been excellent. Currently, the indication spectrum for these valves is narrow, but it may expand with experience.

Are additional laboratory studies available; even some that are not widely available?

Pulmonic stenosis is readily diagnosed non-invasively with an echocardiogram. Anatomic details can be obtained by cardiac catheterization, MRI, or CT angiogram, but these imaging modalities are typically not utilized for diagnostic purposes.

How can pulmonic stenosis be prevented?

Currently there is no way to prevent pulmonic stenosis.