56
Specific Conditions
Table 27. Severity of Right Ventricular Outflow Tract
Dysfunction
Pulmonic stenosis severity*
Degree of
stenosis
Doppler velocity and gradient across the right ventricular outflow
tract
Mild Peak gradient, <36 mm Hg (peak velocity <3 m/s)
Moderate Peak gradient, 36–64 mm Hg (peak velocity 3–4 m/s)
Severe Peak gradient, >64 mm Hg (peak velocity >4 m/s);
Mean gradient >35–40 mm Hg
Pulmonary regurgitation severity
†
Degree of
regurgitation
Regurgitation fraction
and volume, as
measured by CMR
imaging
Echocardiographic features associated
with pulmonic regurgitation
Mild Regurgitant fraction
<20%; regurgitant
volume <30 mL
• Diastolic flow reversal at the pulmonary
valve level
• Narrow vena contracta
• Flat pressure half-time
• Faint density of spectral Doppler signal
Moderate Regurgitant fraction
20%–40%; regurgitant
volume 30–59 mL
• Diastolic flow reversal at the main or
branch pulmonary artery level
‡
• Steep pressure half-time
§
• Low PR index
||
• Denser signal of the spectral Doppler
signal
• Broad vena contracta
Severe Regurgitant fraction
>40%; regurgitant
volume 60 mL
Modified with permission from Stout et al. Copyright © 2018 American Heart Association, Inc.
and American College of Cardiolog y Foundation.
* Severity of pulmonary valve stenosis may be underestimated in the context of ventricular
dysfunction.
†
CMR, the preferred imaging methodolog y for quantifying PR, is used to define the degree
of PR. Echocardiographic features of mild and hemodynamically significant PR also are
listed.
‡
Assessment may be affected by pulmonary arterial compliance.
§
Pressure half-time <100 ms, corresponding to significant PR (defined as regurgitant fraction
≥20% on CMR).
||
PR index (defined as duration of PR signal/total diastolic period) <0.77, corresponding to
PR fraction >24.5%.
CMR indicates cardiovascular magnetic resonance; and PR, pulmonary regurgitation.
