Plain Chest Radiography
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
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:
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Mild: Peak gradient < 30 mmHg
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Moderate: 30-50 mmHg
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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 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 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.
Electrocardiography
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.
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Pulmonic Stenosis. Echocardiogram of a patient with severe pulmonic stenosis. This image shows a parasternal short-axis view of the thickened pulmonary valve.
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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.
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Pulmonic Stenosis. Echocardiogram of a patient with severe pulmonic stenosis. This image shows moderately severe pulmonary insufficiency (orange color flow) is also present.
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Pulmonic Stenosis. This 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; PA = pulmonary artery; PI = pulmonary insufficiency; PV = pulmonary valve.
