12.1 Pulmonic Regurgitation Mechanism and Severity
Key Takeaways
- Separate primary pulmonic regurgitation caused by abnormal cusps or prior intervention from secondary regurgitation caused by pulmonary hypertension and annular or pulmonary-artery dilation.
- Severe primary PR may be low velocity, laminar, brief, and visually unimpressive because pulmonary-artery and RV diastolic pressures equalize rapidly; color jet length or peak velocity alone is unreliable.
- Integrate jet origin and width, CW density and deceleration, branch pulmonary-artery flow reversal, RV size and function, septal motion, and loading conditions rather than treating one cutoff as the grade.
- Use CMR when significant PR is suspected but TTE is incomplete or discordant, particularly after congenital repair, because it directly quantifies regurgitant fraction and provides reproducible RV volumes.
Define mechanism before measuring the jet
CCI task C12 is to assess pulmonic regurgitation (PR). Trace or mild PR is common in otherwise normal adults and usually physiologic. More-than-mild PR requires a mechanism. Primary PR reflects abnormal cusp tissue or direct valve disruption, most often congenital disease, repaired tetralogy of Fallot, surgical RVOT reconstruction, or prior balloon valvuloplasty. Less common causes include endocarditis, carcinoid retraction, rheumatic disease, trauma, and iatrogenic injury. Describe absent, dysplastic, thickened, retracted, prolapsing, perforated, or postintervention tissue when demonstrated.
In secondary PR, the cusps are not the primary lesion. Pulmonary hypertension and dilation of the main pulmonary artery or annulus prevent effective diastolic coaptation. Secondary PR is often high velocity and holodiastolic because PA pressure remains high, yet its regurgitant volume is commonly modest. In contrast, severe primary PR with normal PA pressure may be low velocity, laminar, and very brief because PA and RV diastolic pressures equalize rapidly. A short, faint-looking color jet is therefore not automatically mild.
Obtain parasternal short-axis RVOT, modified RVOT, high parasternal, and subcostal views. Sweep through the valve, annulus, RVOT, main PA, and proximal branches. Optimize color gain and use a Nyquist limit near 50–70 cm/s for standard comparison, then adjust when low-velocity flow is being missed. Document jet origin, multiplicity, direction, and relation to the annulus. PW mapping can distinguish valvar flow from conduit or branch obstruction, while CW should be aligned through the regurgitant jet from the best window.
Build mutually checking severity evidence
The proximal color-jet width or vena contracta is more useful than distal jet area or length. Measure immediately below the valve in early diastole and compare with the pulmonary annulus in the same plane. A broad origin occupying at least about 70% of annular width is a specific severe-pattern sign in native PR, but eccentricity, multiple jets, oblique imaging, gain, and scale can distort the ratio. A narrow jet shorter than about 10 mm supports trivial or mild PR only when the driving pressure and remaining findings agree.
| Evidence | Severe-pattern finding | Critical limitation |
|---|---|---|
| Color origin | Broad vena contracta or jet-width/annulus ratio around 70% or more | Oblique, eccentric, multiple, or low-velocity jets |
| CW density | Dense regurgitant envelope | Central alignment can make a lesser jet appear dense |
| CW timing | Rapid deceleration and early diastolic termination | High RV diastolic pressure or low RV compliance causes rapid equalization |
| Branch PA PW | Prominent diastolic flow reversal | Brief early reversal can be normal; main PA alone is less specific |
| RV response | Chronic RV/RVOT dilation with volume-overload septal motion | Congenital repair, shunt, or TR can enlarge the RV independently |
A pressure half-time below 100 ms, deceleration time below 260 ms, or PR index below 0.77 supports important PR but is not diagnostic alone. The PR index equals PR duration divided by total diastolic duration. Each index reflects the rate or timing of PA–RV pressure equalization and changes with RV compliance, RV end-diastolic pressure, pulmonary pressure, heart rate, and Doppler alignment. Report premature termination rather than converting an incomplete or poorly aligned envelope into a precise measurement.
Sample both right and left branch PAs when feasible. Prominent diastolic reversal in a branch is more specific for severe PR than reversal confined to the main PA; brief early-diastolic reversal is not sufficient. Record forward RVOT/PV flow as well, since markedly greater pulmonic than systemic stroke volume can support regurgitant volume overload when no shunt or other important regurgitation invalidates the comparison.
Quantitative Doppler estimates PR regurgitant volume = RVOT stroke volume − systemic forward stroke volume and regurgitant fraction = PR regurgitant volume / RVOT stroke volume. It is vulnerable to the squared RVOT-diameter error, noncircular geometry, mismatched sample locations and beats, shunts, and other valve regurgitation. EROA is not well validated for PR. A regurgitant fraction below 20%, 20%–40%, or above 40% is commonly used to support mild, moderate, or severe PR, respectively, but the evidence is largely CMR based and does not make Doppler quantitation definitive.
Interpret the right ventricle in context
Use a comprehensive current right-heart examination: an RV-focused apical view, basal and mid dimensions, RV end-diastolic and end-systolic areas, fractional area change, TAPSE, tissue Doppler S′, and additional function measures when feasible. Assess RA size, IVC, TR, estimated pulmonary pressure, RVOT size, and septal shape. Chronic severe primary PR almost always produces RV dilation, initially with preserved function and a diastolic volume-overload pattern; progressive dysfunction may follow. A normal RV argues against chronic severe primary PR unless the lesion is acute. RV enlargement after congenital repair may predate or exceed the current PR burden, while secondary PR in pulmonary hypertension may coexist with pressure-overload remodeling.
If most independent findings are mild or severe and technically valid, classification is confident. Mixed or intermediate findings usually support moderate PR, but unexplained discordance should remain indeterminate. Recheck color settings, jet alignment, branch sampling, RV measurements, rhythm, pulmonary pressure, and prior surgery. CMR directly measures pulmonary forward and reverse flow and is preferred for PR fraction and RV volumes when TTE is incomplete, when the RV enlarges despite an apparently moderate jet, or when congenital intervention is being considered. Communicate suspected vegetation, acute severe PR, conduit complication, or rapid RV deterioration promptly.
After prior pulmonic valvuloplasty, color Doppler shows only a brief low-velocity PR jet, but the jet origin is very broad, CW flow terminates early, both branch pulmonary arteries show prominent diastolic reversal, and the RV is dilated. What is the best interpretation?
Which three actions belong in an integrated assessment of suspected important PR? Select three.
Select all that apply