What are the echocardiogram criteria for diagnosing pulmonic stenosis?

Echocardiographic Criteria for Pulmonic Stenosis

Pulmonic stenosis severity is classified by Doppler peak jet velocity and mean gradient: mild (<3 m/s or <36 mmHg), moderate (3-4 m/s or 36-64 mmHg), and severe (>4 m/s or >64 mmHg). 1

Severity Classification

Quantitative Doppler Criteria

• Mild stenosis: Peak velocity <3 m/s (peak gradient <36 mmHg) 1
• Moderate stenosis: Peak velocity 3-4 m/s (peak gradient 36-64 mmHg) 1
• Severe stenosis: Peak velocity >4 m/s (peak gradient >64 mmHg) 1

These velocity measurements should be obtained using continuous wave (CW) Doppler aligned with the jet stream through the pulmonary valve, recording several cardiac cycles to account for respiratory variation 1

Additional Hemodynamic Assessment

• Tricuspid regurgitation velocity should always be measured to estimate right ventricular systolic pressure, as Doppler gradients may be unreliable in certain situations 1
• Right ventricular systolic pressure can be calculated from the TR jet velocity using the modified Bernoulli equation 1

Qualitative and Morphologic Features

2D Imaging Findings

• Valve morphology: Assess for thickened, dysplastic leaflets, doming or fusion of valve cusps, and restricted leaflet mobility 1
• Right ventricular hypertrophy: Measure anterior RV wall thickness as a marker of chronic pressure overload 1
• Post-stenotic dilatation: Look for dilation of the main pulmonary artery and left pulmonary artery 1

Color Doppler Assessment

• Narrowing of forward color flow map at the valve level suggests obstruction 1
• Turbulent flow across the pulmonary valve indicates stenosis 1

Important Technical Considerations and Pitfalls

When Doppler May Be Unreliable

Doppler gradients can overestimate severity in patients with tubular stenosis or multiple levels of obstruction (subvalvular and valvular stenoses in series) 1. In these cases:

• The measured gradient represents the sum of all obstructions, not just the valve 1
• Always correlate with TR velocity to estimate true RV systolic pressure 1
• Consider additional imaging (CMR or CT) to identify the exact level(s) of obstruction 1

Sampling Technique

• Ensure proper alignment of the Doppler beam with the jet stream to avoid underestimation 1
• Sample from multiple acoustic windows (parasternal short-axis, subcostal views) to capture the highest velocity 1
• Record multiple cardiac cycles during quiet respiration, as velocities vary with the respiratory cycle 1

Associated Findings to Document

Right Ventricular Assessment

• RV size and function: Document RV dilation and systolic function 1
• RV wall thickness: Measure anterior wall thickness as marker of hypertrophy 1
• Interventricular septal motion: Assess for flattening indicating RV pressure overload 1

Concomitant Lesions

• Pulmonary regurgitation: Often coexists with stenosis and should be graded 1
• Atrial septal defect or patent foramen ovale: May allow right-to-left shunting if RV compliance is reduced 1
• Tricuspid regurgitation: Quantify severity and use for RV pressure estimation 1

Prosthetic Pulmonary Valve Criteria

For patients with pulmonary valve prostheses, different thresholds apply 1:

• Bioprosthesis obstruction: Peak velocity ≥3.2 m/s or mean gradient ≥20 mmHg 1
• Homograft obstruction: Peak velocity ≥2.5 m/s or mean gradient ≥15 mmHg 1
• Pressure half-time: ≥230 ms suggests possible obstruction 1

Clinical Correlation Required

The echocardiogram should never be interpreted in isolation but must be integrated with clinical findings 1. Key clinical features include:

• Physical examination: Harsh systolic murmur, wide splitting of S2, dampened carotid upstroke in severe cases 1
• Symptoms: Dyspnea, reduced exercise capacity, syncope, or presyncope suggest hemodynamically significant stenosis 1
• ECG findings: Evidence of right ventricular hypertrophy 1

If there is discordance between clinical findings suggesting severe stenosis and echocardiographic measurements showing mild-moderate stenosis, repeat the echocardiogram with meticulous attention to Doppler alignment or consider cardiac catheterization for definitive assessment 1