Pulmonic Stenosis (Pulmonary Stenosis)

Pulmonic stenosis (pulmonary stenosis) (PS) refers to a dynamic or fixed anatomic obstruction to flow from the right ventricle (RV) to the pulmonary arterial vasculature, which leads to RV pressure overload that in turn causes increased contractility and dilation and results in increased wall stress and compensatory RV hypertrophy.[1] Although most commonly diagnosed and treated in the pediatric population, individuals with complex congenital heart disease are surviving into adulthood and require ongoing assessment and cardiovascular care.[2]  These adults often also have severe heart structural diseases.[1, 3]  Some patients with severe, isolated PS may be diagnosed for the first time as adults.

Pulmonic stenosis (pulmonary stenosis) (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.[1, 3] The characteristics of the various types of PS are described in this section.[4]

Valvular pulmonic stenosis

Isolated valvular PS comprises approximately 10% of all congenital heart disease. Typically, the valve commissures are partially fused and the three 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 or an underlying connective tissue disorder.

Alternatively, approximately 10-15% of individuals with valvular 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.

Bicuspid morphology, while rare in individuals with isolated valvular PS, is more common in those with tetralogy of Fallot.

Subvalvular pulmonic stenosis

Subvalvular PS may be due to an underlying disorder or a secondary phenomenon in the setting of valvular PS. The former is characterized by fibromuscular narrowing of the right ventricular outflow tract and is possibly a variant of double chambered-right ventricle. In contrast, secondary outflow tract narrowing may occur due to primary valvular PS. This typically resolves after correction of valvular stenosis. Subvalvular PS is one of the defining characteristics of tetralogy of Fallot.

Peripheral pulmonary stenosis

Peripheral pulmonary stenosis (PPS) can cause obstruction along the pulmonary artery anywhere from the main pulmonary artery to distal pulmonary artery 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). Up to 20% of 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.

Causes of acquired pulmonic stenosis (pulmonary stenosis) (PS) 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.

See also Pathophysiology.

United States data

Pulmonic stenosis (pulmonary stenosis) (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 in the United States. About 2% of familial occurrences are without a genetic cause.[3]

Sex-related demongraphics

A slight female predominance exists.[3]

Except for critically severe stenosis in neonates, survival is the rule for individuals with congenital pulmonic stenosis (pulmonary stenosis) (PS).[5]  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 moderate and severe PS have an excellent prognosis. 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. Following balloon valvuloplasty, there can be residual PS or pulmonary regurgitation (usually mild or moderate); both may be followed by serial echocardiography. 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%.[6]  Following surgical treatment for isolated pulmonary valve stenosis, a high rate of reinterventions has been reported (53% at a median follow-up of 34 years). Thus, close follow-up in all patients who have undergone intervention is needed.[7]

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 typically 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.

Morbidity/mortality

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 tends to be stable in severity as the 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.

Most children and adults with mild-to-moderate pulmonic stenosis (pulmonary stenosis) (PS) are asymptomatic. Those with severe PS may experience exertional dyspnea and fatigue. They may also report symptoms of right heart failure (peripheral edema, fatigue, dyspnea). In rare cases, patients can present with exertional angina, syncope, or sudden death.

In patients with pulmonic stenosis (pulmonary stenosis) (PS), the jugular venous waveform will reveal a prominent a wave due to forceful right atrial contraction in the setting of a stiff, noncompliant right ventricle.

A precordial heave or a palpable impulse from the right ventricle 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 midsystolic murmur in the left upper sternal border that increases with inspiration and radiates diffusely.

In patients with pliable valve leaflets, a systolic ejection click typically precedes 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-moderate desaturation or frank cyanosis may be noted on pulse oximetry if there is right-to-left shunting through a patent foramen ovale, atrial septal defect, or ventricular septal defect.

A characteristic radiographic finding, even with mild valvular pulmonic stenosis (pulmonary stenosis) (PS), is prominence of the main or branch pulmonary arteries caused by poststenotic dilatation. The intrapulmonary vasculature usually appears normal, even in severe PS. Vascular fullness in the left lung base may exceed that of the right (Chen sign) due to preferential streaming into the left pulmonary artery.

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 provides a definitive confirmation of the diagnosis of pulmonic stenosis (pulmonary stenosis) (PS). Both two-dimensional (2D) and Doppler techniques should be used to comprehensively evaluate the pulmonic valve.

Using 2D 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 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 with severe pulmonic stenosis. This image shows a Doppler scan of the peak velocity (5.2 m/s) and gradients (peak 109 mmHg, mean 65 mmHg) across the valve.

Care should be taken to clarify whether the pulmonary valve is doming or dysplastic; dysplastic valves often do not respond as well to balloon valvuloplasty. Attention should also be directed toward RV hypertrophy, including at the level of the outflow tract and supravalvular PS. The main pulmonary artery may demonstrate poststenotic dilatation. Finally, the degree of pulmonary regurgitation should be assessed. More than mild regurgitation may preclude balloon valvuloplasty and individuals with a prior history of balloon valvuloplasty may have signficant regurgitation. RV hypertrophy may be present, depending upon the severity of PS. In addition, restrictive RV 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.

The grading of PS is as follows:

• Mild: Peak gradient < 30 mmHg
• Moderate: 30-50 mmHg
• Severe: >50 mmHg

Pulmonic Stenosis. Echocardiogram of a patient with severe pulmonic stenosis. This image shows moderately severe pulmonary insufficiency (orange color flow) is also present.

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 pulmonic stenosis (pulmonary stenosis) (PS) by a pressure gradient from the pulmonary artery to the right ventricle (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 peripheral pulmonary stenosis (PPS), cardiac catheterization with pulmonary angiography or computed tomography angiography (CTA) may be needed to establish the diagnosis.

The degree of (right) ventricular hypertrophy on the electrocardiogram (ECG) is largely correlated directly with the severity of pulmonic stenosis (pulmonary stenosis) (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. Deep S waves may be seen in leads V5-V6.

Traditionally, pulmonic stenosis (pulmonary 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 symptomatic patient with a transvalvular peak gradient over 50 mmHg (mean >30 mmHg) and in asymptomatic patients with a peak gradient over 60 mmHg (mean >40 mmHg). It is critical to ensure that no more than moderate pulmonic valve regurgitation is present prior to valvuloplasty. Providers should be aware of the possibility of "suicidal RV," in which there is severe, dynamic right ventricular outflow tract (RVOT) obstruction acutely following relief of valvar PS. This can be managed by beta blockers and volume expansion.

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. A 2020 case report from Japan was the first to describe successful balloon pulmonary angioplasty intervention for Noonan syndrome with pulmonary artery stenosis.[8]  The clinicians used a strategy of careful morphologic evaluation with computed tomographic angiography and used scoring balloons over multiple sessions in a graded approach.

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 (AHA/ACA)[2] and European Society of Cardiology (ESC)[9, 10]  adult congenital heart disease guidelines may be reviewed for further details regarding diagnosis and management. (See also the Guidelines section.) The AHA/ACC[11]  and ESC[12] ​ guidelines on the management of patients with valvular heart disease are also available.

Infective endocarditis prophylaxis

The 2017 American Heart Association (AHA)/American College of Cardiology (ACC) focused update of the 2014 AHA/ACC guideline for the management of patients with valvular heart disease no longer recommends antibiotic prophylaxis for isolated PS.[13]

Pregnancy

Avoidance of vigorous exercise in pregnancy is recommended, especially during the second half of pregnancy in patients with moderate or severe pulmonic stenosis (pulmonary stenosis) (PS). 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.[14]

Athletes

Athletes with mild PS stenosis (peak gradient < 30 mmHg) and normal right ventricular (RV) function have no activity limitations.

Athletes treated by operation or balloon valvuloplasty with only mild residual gradients (< 30 mmHg) have no activity restrictions.

Those with moderate (30-50 mmHg) or severe (>50 mmHg) PS can participate in low-intensity competitive sports; their treatment should be directed by the criteria discussed in Treatment.

The European Society of Cardiology (ESC) updated their 2010 guidelines on the management of adult congenital heart disease (ACHD) in 2020.[9, 10]  Select class I and III recommendations are outlined.

RV Outflow Tract Obstruction (OTO)

In valvular pulmonary stenosis (PS), balloon valvuloplasty is the intervention of choice, if anatomically suitable.

As long as no valve replacement is required, RVOTO intervention at any level is recommended regardless of symptoms when the stenosis is severe (Doppler peak gradient >64 mmHg).

If surgical valve replacement is the only option, it is indicated in (1) symptomatic patients with severe stenosis; or (2) asymptomatic patients with severe stenosis in the presence of ≥1 of the following:

• Objective decrease in exercise capacity
• Falling RV function and/or progression of tricuspid regurgitation (TR) to at least moderate
• RV systolic pressure (SP) >80 mmHg
• Right-to-left (RL) shunting via an ASD or VSD

CHD-Associated Pulmonary Arterial Hypertension (PAH)

Counsel patients with congenital heart disease (CHD) and confirmed precapillary pulmonary hypertension (PH) against pregnancy.

All patients with PAH-CHD should undergo risk assessment.

In low- and intermediate-risk patients with repaired simple lesions and precapillary PH, initial oral combination therapy or sequential combination therapy is recommended; treat high-risk patients with initial combination therapy including parenteral prostanoids.

After Repair of Tetralogy of Fallot

Pulmonary valve replacement (PVRep) is recommended in symptomatic patients with severe pulmonary regurgitation (PR) and/or at least moderate RVOTO.

In those without a native outflow tract, catheter intervention (transcatheter pulmonary valve implantation [TPVI]) is preferred if anatomically feasible.