From the Guidelines
Pulmonic stenosis is graded according to peak systolic velocity measurements obtained through Doppler echocardiography, with mild stenosis characterized by a peak velocity less than 3 m/s, moderate stenosis between 3 and 4 m/s, and severe stenosis exceeding 4 m/s, as supported by the most recent and highest quality study 1. The grading of pulmonic stenosis is crucial for clinical decision-making, as it determines the need for intervention or conservative monitoring.
- Mild pulmonic stenosis is characterized by a peak velocity less than 3 m/s, corresponding to a pressure gradient below 36 mmHg.
- Moderate stenosis shows velocities between 3 and 4 m/s, with pressure gradients of 36-64 mmHg.
- Severe pulmonic stenosis is diagnosed when the peak velocity exceeds 4 m/s, creating a pressure gradient greater than 64 mmHg. These velocity measurements are derived from the modified Bernoulli equation (pressure gradient = 4v²), which relates blood flow velocity to pressure differences across the stenotic valve, as noted in 1. Regular echocardiographic assessment is important for patients with pulmonic stenosis to monitor disease progression and determine appropriate timing for intervention, with additional imaging modalities such as CMR and CT providing valuable information on the level and severity of obstruction, as discussed in 1. It's also worth noting that Doppler measurements may be unreliable in certain cases, such as tubular stenosis or stenoses in series, and therefore should be used in conjunction with other diagnostic tools, such as TR velocity and estimation of RV pressure, as recommended in 1.
From the Research
Pulmonic Stenosis Grading According to Velocities
Pulmonic stenosis can be graded according to velocities, which is crucial for determining the severity of the condition and the need for intervention. The grading is typically based on the peak velocity in the pulmonary artery, as measured by Doppler echocardiography.
- The study by 2 categorized patients into three groups based on peak velocity: above 3.54 m/sec, between 3.54 and 2.74 m/sec, and less than 2.74 m/sec.
- Another study by 3 found that the mean Doppler gradient showed the best correlation and agreement with the catheter peak-to-peak gradient, and suggested that the mean Doppler gradient should be used to determine the severity of pulmonary valve stenosis.
- The severity of pulmonic stenosis can be classified as follows:
- Mild: peak velocity less than 2.74 m/sec or mean Doppler gradient less than 20 mmHg
- Moderate: peak velocity between 2.74 and 3.54 m/sec or mean Doppler gradient between 20 and 40 mmHg
- Severe: peak velocity above 3.54 m/sec or mean Doppler gradient above 40 mmHg
- It is essential to note that the grading of pulmonic stenosis may vary depending on the specific criteria used, and the decision to intervene should be based on a comprehensive evaluation of the patient's condition, including symptoms, echocardiographic findings, and catheterization data, as discussed in studies by 4, 5, and 6.