What is the grade of pulmonic (pulmonary) stenosis on echocardiogram (echo)?

From the Guidelines

Grading pulmonic stenosis on echocardiography is based on Doppler-derived peak instantaneous gradients, with mild stenosis indicated by a gradient <40 mm Hg, moderate stenosis by a gradient of 40 to 60 mm Hg, and severe stenosis by a gradient >60 mm Hg, as recommended by the American Heart Association and American College of Cardiology 1.

Key Considerations for Grading

• The assessment of pulmonic stenosis severity is crucial for determining the appropriate management strategy, with severe cases potentially requiring intervention to prevent long-term complications such as right ventricular failure.
• Echocardiography is a key diagnostic tool, with Doppler-derived peak instantaneous gradients providing a direct measure of stenosis severity.
• Additional echocardiographic features, such as right ventricular hypertrophy, right atrial enlargement, and post-stenotic dilation of the pulmonary artery, can provide supporting evidence for the severity of pulmonic stenosis.

Echocardiographic Evaluation

• The evaluation should include multiple views, including parasternal short axis at the level of the great vessels and the right ventricular outflow tract.
• Color Doppler should be used to identify the area of turbulence, followed by continuous wave Doppler aligned parallel to flow to measure the peak velocity accurately.
• The peak velocity across the pulmonic valve and the corresponding pressure gradient are critical for determining the severity of stenosis, with severe stenosis characterized by a jet velocity greater than 4 m per second or maximum gradient greater than 60 mmHg, as noted in the ACC/AHA 2006 guidelines 1.

Management Implications

• The severity of pulmonic stenosis determines management decisions, with severe cases often requiring intervention such as balloon valvuloplasty or surgical repair, while mild cases may only need monitoring.
• Accurate grading of pulmonic stenosis is essential to balance the risks and benefits of intervention and to prevent unnecessary procedures in cases with mild disease.

From the Research

Grading Pulmonic Stenosis on Echo

To grade pulmonic stenosis on echo, several factors need to be considered, including the Doppler gradient and its correlation with catheter-derived gradients.

• The maximal Doppler gradient has been shown to correlate well with the catheter-derived peak-to-peak pressure gradient 2 and maximal instantaneous pressure gradient 2.
• However, the maximal Doppler gradient may overestimate the peak-to-peak catheter gradient by as much as 25%-40% 2.
• The mean Doppler gradient has been found to show the best correlation and agreement with the catheter peak-to-peak gradient (PPG) 3.
• Outpatient mean Doppler gradient is most predictive of subsequent PPG and should be used to determine whether to intervene for patients with isolated pulmonary valve stenosis 3.

Doppler Gradient Measurements

• Maximum instantaneous Doppler gradient has been the primary variable used to assess severity of pulmonary valve stenosis 3.
• Mean Doppler gradient is a better predictor of catheter PPG than maximum Doppler gradient 3.
• The use of only the maximum Doppler gradient to assess pulmonary valve stenosis will lead to a systematic overstatement of the severity of the stenosis 3.

Clinical Validity of Doppler Gradients

• The clinical validity of Doppler gradients in assessing pulmonary valve stenosis has been evaluated in several studies 4, 5, 2, 3, 6.
• These studies have shown that Doppler echocardiography is a useful tool in assessing the severity of pulmonary valve stenosis and in monitoring the effects of treatment 4, 5, 6.