Pediatrics

Pulmonic stenosis

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.

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

  2. Dyspnea on exertion or fatigue

  3. 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 type of right ventricular outflow obstruction, either below, at, or 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 of Pulmonic Stenosis by Echocardiography
Severity Grade Pressure Gradient RV Pressure / LV Pressure Ratio
Mild <35-40mmHg <50%
Moderate 40-60mmHg 50%-75%
Severe >60mmHg >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.

Treatment Options for Pulmonic Stenosis
Advantages Disadvantages
Catheter-based Balloon Pulmonic Valvuloplasty Less invasive than surgery Can result in pulmonic insufficiency
Excellent results when pulmonary valve leaflets are thin Poorer results with thickened, dysplastic leaflets
Shorter inpatient recovery
No sternotomy needed
Surgical Pulmonic Valvotomy More precise repair of pulmonary valve than balloon Midline sternotomy required
Ability to repair sub-valvar and supra-valvar obstruction Longer inpatient recovery period
Preferred option for thickened, dysplastic pulmonary valve leaflets
Pulmonary valve replacement available at the time of treatment

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. Fortunately, when considering all cases of pulmonic stenosis, this outcome 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.

What is the evidence?

Selected References:

Prieto, LR, Latson, LA, Allen, HD, Driscoll, DJ, Shaddy, RE, Feltes, TF. "Pulmonary stenosis". Moss and Adams' heart disease in infants, children and adolescents: including the fetus and young adult. Lippincott Williams & Wilkins. 2008. pp. 835-58.

(This textbook chapter provides information about the embryology, pathophysiology, clinical manifestations, differential diagnosis, treatment, course, and prognosis for children born with pulmonary valve stenosis.)

McCrindle, BW. "Independent predictors of long-term results after balloon pulmonary valvuloplasty. Valvuloplasty and Angioplasty of Congenital Anomalies (VACA) Registry Investigators". Circulation. vol. 89. 1994. pp. 1751-9.

(This multi-center follow-up study of 533 patients was performed to determine independent predictors of long-term outcome after percutaneous balloon dilation of congenital pulmonary valve stenosis. Twenty-three percent of patients had a suboptimal outcome (either a residual gradient of > or = 36 mm Hg or further treatment requiring repeat balloon valvuloplasty or surgical therapy). Significant independent predictors of a suboptimal long-term outcome included an earlier study year of the initial valvuloplasty (adjusted odds ratio, 0.71 per consecutive year), a small valve hinge point diameter (0.81 per 1-mm increase), and a higher immediate residual gradient (1.32 per 10-mm Hg increase). Accurate prognostication after balloon pulmonary valvuloplasty depends on the careful determination of valvular anatomy.)

Garty, Y, Veldtman, G, Lee, K, Benson, L. "Late outcomes after pulmonary valve balloon dilation in neonates, infants and children". J Invasive Cardiol. vol. 17. 2005. pp. 318-22.

(This review of 150 children with pulmonary valve stenosis was designed to document late outcomes after balloon dilation. PV gradients decreased from 62 +/- 29 to 23 +/- 20 mmHg (p<0.0001) and remained low during a mean follow-up of 11.9 +/- 3.1 (range 3.7 to 19.3 years). Freedom from re-intervention at 1, 10 and 15 years were: 90%, 83%, and 77%. Pulmonary regurgitation (PR) increased during follow-up such that 57% of children had moderate or severe PR at last follow-up. Only children with severe PR demonstrated a significant increase in right ventricular (RV) size. The PV demonstrated catch-up growth (PV z-score: negative 1.3 vs. negative 0.7 at last follow-up, p = 0.04). While life-long follow-up is essential, excellent outcome can be anticipated.)

McElhinney, DB, Hellenbrand, WE, Zahn, EM. "Short- and medium-term outcomes after transcatheter pulmonary valve placement in the expanded multicenter US melody valve trial". Circulation. vol. 122. 2010. pp. 507-16.

(This report from the multicenter US Melody valve trial demonstrated an ongoing high rate of procedural success and encouraging short-term valve function. There were 136 patients (median age, 19 years) who underwent catheterization for intended Melody valve implantation, with implantation attempted in 124 patients. The median peak right ventricular outflow tract gradient was 37mmHg before implantation and 12 mmHg immediately after implantation. Before implantation, pulmonary regurgitation was moderate or severe in 92 patients (81% with data); no patient had more than mild pulmonary regurgitation early after implantation or during follow-up (>or= 1 year in 65 patients). Freedom from diagnosis of stent fracture was 77.8% +/- 4.3% at 14 months. Freedom from Melody valve dysfunction or reintervention was 93.5% +/- 2.4% at 1 year.)

Driscoll, DJ, Michels, VV, Gersony, WM. "Occurrence risk for congenital heart defects in relatives of patients with aortic stenosis, pulmonary stenosis, or ventricular septal defect". Circulation. vol. 87. 1993. pp. I114-20.

(This study reports the results of a questionnaire mailed to all patients in the Second Natural History Study of Congenital Heart Defects (NHS-2), and addressed presence or absence of congenital heart defects or other congenital malformations in first-degree relatives. Offspring were not examined as a part of the study. For patients with pulmonary stenosis (PS), three of 176 offspring of male probands had congenital heart disease, whereas 8 of 205 offspring of female probands had congenital heart disease. Based on known congenital heart defects in offspring of probands in the NHS-2, occurrence rates of congenital heart disease in children of subjects with PS was 2.8% (CI, 1.4%-5.1%).)

Gersony, WM, Hayes, CJ, Driscoll, DJ. "Second Natural History Study of Congenital Heart Defects. Quality of life of patients with aortic stenosis, pulmonary stenosis, or ventricular septal defect". Circulation. vol. 87. 1993. pp. I52-65.

(This study reports the results of a questionnaire mailed to all patients in the Second Natural History Study of Congenital Heart Defects (NHS-2), and addressed medical history, marital and family life, self-perception of well-being, insurability, and employability. The study cohort reported a self-perception of health status similar to that of the general population. Thirty-five to forty percent of patients had not had a cardiac evaluation within the previous 10 years. Sixteen percent of the patients had no health insurance, and 35.7% of the patients had no life insurance. For the patients with pulmonary stenosis, the percent who were married was less than that of the corresponding national age- and sex-specific population. The proportion of divorced or separated individuals was similar to that of the general population. The level of educational attainment exceeded the national average. Unemployment rates were similar to national averages. Patients with pulmonary stenosis diagnosed from 1959-1973 have a quality of life in the mid-1980s similar to that of the general US population.)

Ongoing controversies regarding etiology, diagnosis, treatment

It is generally accepted that the preferred option for the initial treatment of pulmonic stenosis, when severe enough to warrant treatment, is catheter-based balloon valvuloplasty, even if the valve morphology is dysplastic and thickened. The results of valvuloplasty are typically sufficient to relieve the obstruction, and the development of significant insufficiency is uncommon.

If balloon valvuloplasty is unsuccessful in relieving obstruction, then patients are typically referred for surgical valvotomy. This method of treatment also has typically excellent results but is more invasive.

There is some controversy regarding whether to intervene in moderate pulmonic stenosis (defined as a gradient >40 mmHg or right ventricular pressure between 50%-75% of left ventricular pressure). Infants and young children with moderate pulmonic stenosis will often progress to worsening gradients, with most changes occurring during periods of rapid somatic growth. While older children and adults with moderate stenosis are typically asymptomatic, they have been shown to have decreased cardiac output during formal exercise testing. Most centers will intervene upon a gradient >40 mmHg.

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