Pulmonic Stenosis 

Updated: Dec 22, 2014
Author: Xiushui (Mike) Ren, MD; Chief Editor: Richard A Lange, MD, MBA 

Overview

Background

Pulmonic stenosis (PS) refers to a dynamic or fixed anatomic obstruction to flow from the right ventricle (RV) to the pulmonary arterial vasculature. Although most commonly diagnosed and treated in the pediatric population, individuals with complex congenital heart disease and more severe forms of isolated PS are surviving into adulthood and require ongoing assessment and cardiovascular care.[1]

Pathophysiology

PS can be due to isolated valvular (90%), subvalvular, or peripheral (supravalvular) obstruction, or it may be found in association with more complicated congenital heart disorders. The characteristics of the various types of PS are described in this section.[2]

Valvular pulmonic stenosis

Isolated valvular PS comprises approximately 10% of all congenital heart disease. Typically, the valve commissures are partially fused and the 3 leaflets are thin and pliant, resulting in a conical or dome-shaped structure with a narrowed central orifice. Poststenotic pulmonary artery dilatation may occur owing to "jet-effect" hemodynamics.

Alternatively, approximately 10-15% of individuals with valvar PS have dysplastic pulmonic valves. These valves have irregularly shaped, thickened leaflets, with little, if any, commissural fusion, and they exhibit variably reduced mobility. The leaflets are composed of myxomatous tissue, which may extend to the vessel wall. The valve annulus is usually small, and the supravalvular area of the pulmonary trunk is usually hypoplastic. Poststenotic dilatation of the pulmonary artery is uncommon. Approximately two thirds of patients with Noonan syndrome have PS due to dysplastic valves.

A bicuspid valve is found in as many as 90% of patients with tetralogy of Fallot, whereas it is rare in individuals with isolated valvar PS.

With severe valvular PS, subvalvular right ventricular hypertrophy can cause infundibular narrowing and contribute to the right ventricular outflow obstruction. This often regresses after correction of valvular stenosis.

With severe PS and decreased right ventricular chamber compliance, cyanosis can occur from right-to-left shunting if a concomitant patent foramen ovale, atrial septal defect, or ventricular septal defect is present.

Subvalvular pulmonic stenosis

Subvalvular PS occurs as a narrowing of the infundibular or subinfundibular region, often with a normal pulmonic valve. This condition is present in individuals with tetralogy of Fallot and can also be associated with a ventricular septal defect (VSD).

Double-chambered right ventricle is a rare condition associated with fibromuscular narrowing of the right ventricular outflow tract with right ventricular outflow obstruction at the subvalvular level.

Peripheral pulmonary stenosis

Peripheral pulmonary stenosis (PPS) can cause obstruction at the level of the main pulmonary artery, at its bifurcation, or at the more distal branches. PPS may occur at a single level, but multiple sites of obstruction are more common. PPS may be associated with other congenital heart anomalies such as valvular PS, atrial septal defect (ASD), VSD, or patent ductus arteriosus (PDA); 20% of the patients with tetralogy of Fallot have associated PPS.

Functional or physiologic PPS is a common cause of a systolic murmur in infants. It occurs in both premature and full-term infants; with time, the pulmonary artery grows, and the murmur usually disappears within a few months.

Poststenotic dilatation occurs with discrete segmental stenosis but is absent if the stenotic segment is long or if the pulmonary artery is diffusely hypoplastic.

PPS is associated with various inherited and acquired conditions including rubella and the Alagille, cutaneous laxa, Noonan, Ehlers-Danlos, and Williams syndromes.

Epidemiology

Frequency

United States

PS is a common form of congenital heart disease that occasionally is diagnosed for the first time in adulthood. Isolated valvular PS comprises approximately 10% of all congenital heart disease.

Mortality/Morbidity

Except for critical stenosis in neonates, survival is the rule in congenital PS.

The long-term course of patients with mild PS is indistinguishable from that of the unaffected population. Mild PS does not tend to progress in severity; rather, pulmonic valve orifice size usually increases with body growth. However, untreated severe PS may result in outflow obstruction that progresses over a period of years; 60% of patients with severe PS require intervention within 10 years of diagnosis.

Sex

A slight female predominance exists.

 

Presentation

History

Most children and adults with mild-to-moderately severe pulmonic stenosis (PS) are asymptomatic. Those with severe PS may experience exertional dyspnea and fatigue.

In extremely rare cases, patients present with exertional angina, syncope, or sudden death.

Peripheral edema and other typical symptoms occur with right heart failure.

Cyanosis is present in those with significant right-to-left shunt via a patent foramen ovale, atrial septal defect, or ventricular septal defect.

Physical

A precordial heave or a palpable impulse from the RV along the left parasternal border may suggest severe PS. In the left upper sternal border, a systolic thrill may be palpable at the level of the second intercostal space.

In valvular PS, auscultation reveals a normal S1 and a widely split S2, with a soft and delayed P2. Valvular PS typically causes a systolic crescendo-decrescendo ejection murmur in the left upper sternal border that increases with inspiration and radiates diffusely.

In patients with pliable valve leaflets, a systolic ejection click may precede the murmur, distinguished from aortic ejection sounds by its increased intensity on expiration and softening on inspiration. As the severity of PS increases, the ejection murmur increases in intensity, its duration prolongs, and its peak becomes more delayed. No ejection click is heard when dysplasia or severe leaflet thickening immobilizes the valve leaflets, or if the stenosis is above or below the pulmonic valve.

The murmur of PPS may be continuous, softer, and higher pitched.

Mild-to-moderately severe desaturation or frank cyanosis may be noted with right-to-left shunting through a patent foramen ovale, atrial septal defect, or ventricular septal defect.

Causes

See also Pathophysiology.

Other forms of acquired pulmonic stenosis include the following:

  • PS is a rare manifestation of rheumatic heart disease, and it follows involvement of the mitral and aortic valves.

  • Carcinoid may result in development of myxomatous plaques in the RV outflow tract, with distortion and constriction of the pulmonic ring, as well as fusion or destruction of pulmonary valve leaflets, resulting in both stenosis and regurgitation.

  • Rarely, cardiac tumors can grow on or into the RV outflow tract and cause flow obstruction.

  • Sinus of Valsalva aneurysms and aortic graft aneurysms are extracardiac entities that can cause PS by external compression.

 

DDx

Diagnostic Considerations

Other conditions to be considered in patients with suspected pulmonic stenosis include the following:

  • Congenital heart abnormality (see Causes)

  • Rheumatic valvular heart disease

  • Carcinoid heart disease

Pulmonic stenosis in pregnancy

Valvular heart disease, including PS, should warrant follow-up care by a high-risk obstetrics team. The hemodynamic changes in pregnancy—which include increase in plasma volume proportionally greater than red blood cell volume, increase in cardiac stroke volume, decrease in systemic vascular resistance, decrease in pulmonary vascular resistance with a drop in pulmonary pressures, and decrease in venous return that is more marked in the third trimester—can exacerbate the symptoms of PS.

In general, pregnancy is tolerated well by individuals who have asymptomatic PS before conception, even if the degree of stenosis is severe.

When symptoms are referable to PS, they are similar to those of individuals who are not pregnant and symptomatic. The symptoms of healthy pregnancy can resemble those of PS, including exertional fatigue, dyspnea, orthopnea, presyncope, and, rarely, frank syncope. Palpitations due to arrhythmias have been noted to be more common in those with PS.

Mild PS produces a murmur similar to that of the benign flow murmur of pregnancy, which typically increases in intensity as the stroke volume is augmented. During the physical examination, this murmur can be distinguished from the flow murmur of pregnancy by noting a prominent jugular venous a wave, an RV lift, a systolic thrill over the pulmonic area, a pulmonic ejection click, and a diminished or absent P2. ECG and echocardiographic evaluation are essential in confirming clinical suspicion. Fetal echocardiography is indicated in patients with PS or tetralogy of Fallot.

Treatment in pregnancy

Avoidance of vigorous exercise is recommended, especially during the second half of pregnancy in patients with moderate-to-severe gradients.

Balloon valvuloplasty is recommended in nonpregnant patients when the gradient across the right ventricular outflow track is greater than 50 mm Hg at rest or when the patient is symptomatic.

If severe PS is detected during pregnancy, percutaneous balloon valvuloplasty to relieve the obstruction usually can be accomplished safely, obviating the need to terminate the pregnancy.

Arrhythmias are treated according to the severity of symptoms.

Considerations for labor and delivery

Patients who are asymptomatic during pregnancy generally tolerate labor and delivery well.

For more severe valvular disease, a high-risk obstetrics team along with a cardiology consultation may be required to manage deliveries.

Antibiotic prophylaxis generally is not recommended for cesarean delivery and is considered optional in women with PS that is associated with complex congenital heart disease.

See AHA Guidelines on prevention of Infective Endocarditis.

Pulmonic stenosis in athletes

Athletes with mild PS gradients (ie, < 50 mm Hg) have no activity limitations.

Those with more severe PS can participate in low-intensity competitive sports; their treatment should be directed by the criteria discussed in Treatment.

Differential Diagnoses

 

Workup

Plain Chest Radiography

A characteristic radiographic finding, even with mild valvular pulmonic stenosis (PS), is prominence of the main, right, or left pulmonary arteries caused by poststenotic dilatation.

The intrapulmonary vasculature usually appears normal, even in severe PS.

In critical PS, the pulmonary vasculature may appear decreased if significant right-to-left shunting occurs through a patent foramen ovale or atrial septal defect or if severe unilateral pulmonary artery branch obstruction is present.

The overall heart size usually is normal unless RV failure or tricuspid regurgitation develops.

A prominent right heart border suggesting right atrial enlargement may be present in as many as 50% of affected individuals.

Echocardiography

Echocardiography provides a definitive confirmation of the diagnosis of PS. Both 2-dimensional and Doppler techniques should be used to comprehensively evaluate the pulmonic valve.

Using 2-dimensional imaging, thickening of the valves, characteristic doming of nondysplastic valves, and right ventricular (RV) hypertrophy can be noted readily (see image below). RV size and systolic function, right atrial (RA) size, and pulmonary artery dimensions can be quantified in most patients.

Pulmonic stenosis. Echocardiogram of a patient wit Pulmonic stenosis. Echocardiogram of a patient with severe pulmonic stenosis. This image shows a parasternal short axis view of the thickened pulmonary valve.

Color Doppler aids in both defining high velocity jets and localizing their origin. Pulsed waved Doppler (placed just proximal to the site of obstruction) and continuous wave Doppler are used to measure jet velocity, which can be converted to pressure gradient using the modified Bernoulli equation. Normally, no systolic gradient is present across the pulmonic valve. With PS, however, the RV systolic pressure increases and a pressure gradient occurs between the RV and pulmonary artery. Doppler studies of the stenotic valve can determine the severity of the gradient (see image below).

Pulmonic stenosis. Echocardiogram of a patient wit Pulmonic stenosis. Echocardiogram of a patient with severe pulmonic stenosis. This image shows a Doppler scan of the peak velocity (5.2 m/s) and gradients (peak 109 mm Hg, mean 65 mm Hg) across the valve.

The pulmonary valve area of a healthy adult is 2.0 cm2/m2 of body surface area. Mild valvular PS is defined by a valve area larger than 1 cm2 and a transvalvular pressure gradient of less than 50 mm Hg. Moderately severe PS occurs if the valve area is 0.5-1.0 cm2, with a transvalvular pressure gradient between 50 and 75 mm Hg. Severe PS is defined by a valve area smaller than 0.5 cm2 and a transvalvular pressure gradient greater than 75 mm Hg.

RV hypertrophy with asymmetric septal hypertrophy may be present. In addition, restrictive physiology can be demonstrated by Doppler interrogations of tricuspid inflow, hepatic vein flow, and Doppler tissue imaging. A restrictive RV pattern is associated with worse RV systolic function and worse exercise tolerance.

Doppler evidence of right-sided pressures approaching or exceeding systemic pressures or a 2-dimensional echocardiogram demonstrating paradoxical septal motion during systole with reversal of the usual right convex curvature of the interventricular septum is an indication for therapeutic intervention (see image and video below).

Pulmonic stenosis. Echocardiogram of a patient wit Pulmonic stenosis. Echocardiogram of a patient with severe pulmonic stenosis. This image shows that moderately severe pulmonary insufficiency (orange color flow) is also present.
This video is an echocardiogram of a patient with severe pulmonic stenosis. The first segment shows the parasternal short axis view of the thickened pulmonary valve. The second segment shows the presence of moderate pulmonary insufficiency (orange color flow).AV=Aortic valve, PV=Pulmonary valve, PA=Pulmonary artery, PI=Pulmonary insufficiency

Cardiac Catheterization and Pulmonary Angiography

Cardiac catheterization generally is not needed to verify the findings of noninvasive tests, except when a significant discrepancy is noted between clinical findings and echocardiographic findings. When performed, cardiac catheterization can diagnose PS by a pressure gradient from the pulmonary artery to the RV on "pull-back" of the pulmonary artery catheter. Cardiac catheterization may be useful in assessing the presence of concomitant congenital abnormalities.

In the case of isolated PPS, pulmonary angiography may be needed to establish the diagnosis.

Electrocardiography

The degree of (right) ventricular hypertrophy on the ECG is largely correlated directly with the severity of PS.

With mild PS, 50% of patients have a normal ECG tracing or only mild right-axis deviation.

With moderately severe PS, right-axis deviation and increased R-wave amplitude in V1 are seen.

Severe PS is associated with extreme right-axis deviation, a dominant R wave in AVR, and a prominent R wave (>20 mm) in V1.

 

Treatment

Surgical Care

Traditionally, pulmonic stenosis (PS) was treated by surgical valvotomy. Since its introduction in 1982, however, percutaneous balloon valvuloplasty has become the initial intervention in children, adolescents, and adults with congenital valvar PS. Balloon valvuloplasty should be considered in any patient with a transvalvular pressure gradient greater than 50 mm Hg.

Occasionally, balloon valvuloplasty is not successful. These patients tend to have valvular dysplasia (eg, Noonan syndrome) or a hypoplastic pulmonic valve annulus and, therefore, may require surgical valvotomy.

Pulmonary artery balloon angioplasty with or without placement of an expandable metal stent can be used to treat supravalvular PS and PPS. Expandable metal stents can overcome an obstruction successfully; however, the need for stent reexpansion as the individual grows remains problematic.

The American Heart Association/American College of Cardiology[3] and the European Society of Cardiology[4] have published guidelines on the management of patients with valvular heart disease.

Activity

Pregnancy

Avoidance of vigorous exercise in pregnancy is recommended, especially during the second half of pregnancy in patients with moderate or severe gradients.

One study found that pregnant patients with PS had favorable outcomes and low maternal and fetal complications. This is in contrast to left heart obstructive lesions such as aortic and mitral stenosis.[5]

Athletes

Athletes with mild PS and gradients less than 50 mm Hg have no activity limitations. Those with more severe PS can participate in low-intensity competitive sports.

For more details, see Diagnostic Considerations.

 

Follow-up

Deterrence/Prevention

Infective endocarditis prophylaxis: The American Heart Association (AHA) Guidelines on Prevention of Bacterial Endocarditis considers all forms of isolated pulmonic stenosis (PS) to be in the moderate-risk category, and any PS associated with complex congenital heart disease to be in the high-risk category. Therefore, antibiotic prophylaxis is recommended for all forms of PS.

Prognosis

Except for critically severe stenosis in neonates, survival is the rule for individuals with congenital PS.[6] The long-term course of individuals with mild PS is indistinguishable from that of the unaffected population. Mild PS does not tend to progress in severity; rather, pulmonic valve orifice size usually increases with body growth.

Severe PS may result in outflow obstruction that progresses over a period of years despite body growth (60% of patients require intervention within 10 y of diagnosis). With appropriate intervention, those with moderately severe PS have an excellent prognosis.

The functional effect of PS may change during an individual's lifetime such that symptoms or limitations occurring in childhood may resolve by adulthood.

Available data support relieving moderately severe and severe PS in childhood, with follow-up care through adolescence and into adulthood. When PS is corrected during childhood, the life expectancy of the affected individual matches that of the unaffected age- and sex-matched cohort. The more severe and protracted the course of PS, the less optimal the outcome of intervention, including death due to RV failure in the most severe cases.

Balloon valvuloplasty is preferred, provided the valve is compliant and mobile. Those with severe valvular fibrocalcific thickening are more likely to require a surgical approach. The recurrence rate of PS in patients who are treated surgically is approximately 4%. Long-term results of balloon valvuloplasty are comparable to the results of surgical repair, with the rate of recurrence of severe PS less than 5%. A recent study shows that long-term follow-up of patients after surgical treatment for isolated pulmonary valve stenosis resulted in a high rate of reinterventions (53% at a median follow-up of 34 years). Thus, close follow-up in postsurgical patients is needed.

Adult patients are more likely to present with subvalvular hypertrophic pulmonic stenosis or valvular fibrocalcific thickening. Secondary subvalvular hypertrophic stenosis regresses following correction of the primary valvular abnormality, and residual dilatation of the pulmonary trunk is not significant clinically, even when marked. Recognizing subvalvular hypertrophy is important, since it may lead to dynamic outflow obstruction during the acute phase following correction of valvular stenosis. With few exceptions, postvalvuloplasty pulmonic regurgitation is of mild-to-moderate severity.

A study by Zdradzinski et al indicated that specific guidelines for the timing of valve replacement need to be developed for patients with isolated PS who develop pulmonic regurgitation after surgical valvotomy. The study, which involved 109 adult patients, including 34 patients with isolated PS and 75 with tetralogy of Fallot, investigated whether recommendations for valve replacement in patients with tetralogy of Fallot who develop pulmonic regurgitation after complete repair can be applied when regurgitation develops after valvotomy for isolated PS.[7]

The report found that the degrees of pulmonic regurgitation and symptom severity were similar between the two groups of patients, but an analysis of biventricular systolic function and QRS width indicated that the morphologic changes that occur in association with tetralogy of Fallot and its repair involve more than just the effects of pulmonic regurgitation.[7]