Pulmonary valve area
PVA · Continuity equation: PVA = [π(RVOT D/2)2 × RVOT VTI] / PV VTI. Rarely required — severity is graded by gradient
Normal range & thresholds
Normal ≈2.0 cm² (roughly 1.9–2.2 cm², or ≈1.0–1.2 cm²/m² indexed).
Be explicit about the evidence status: unlike the aortic and mitral valves, pulmonary valve area is not a guideline severity criterion. Pulmonary stenosis is graded by peak velocity and gradient — mild <3 m/s (<36 mmHg), moderate 3–4 m/s (36–64 mmHg), severe >4 m/s (>64 mmHg) — and intervention thresholds are defined on gradient, not area.[25] PVA is used mainly in prosthetic and conduit assessment, and in low-flow states where gradient misleads.
Be explicit about the evidence status: unlike the aortic and mitral valves, pulmonary valve area is not a guideline severity criterion. Pulmonary stenosis is graded by peak velocity and gradient — mild <3 m/s (<36 mmHg), moderate 3–4 m/s (36–64 mmHg), severe >4 m/s (>64 mmHg) — and intervention thresholds are defined on gradient, not area.[25] PVA is used mainly in prosthetic and conduit assessment, and in low-flow states where gradient misleads.
Pathophysiology
Identical continuity physiology to the aortic valve, applied to a right-sided circuit whose lower pressures and greater compliance make gradients more flow-sensitive and pressure recovery more prominent. The reason area is rarely calculated is practical rather than conceptual: the RVOT diameter is harder to measure reproducibly than the LVOT, and it is squared, so the derived area carries more error than the gradient it was meant to refine.[20,25]
Raised by
- After balloon valvuloplasty or valve replacement
- Overestimated by an over-measured RVOT diameter or by an underestimated transvalvular jet
Lowered by
- Congenital valvular pulmonary stenosis — the dominant aetiology; domed (typical) or dysplastic (Noonan syndrome)
- Carcinoid heart disease (thickened, retracted, immobile cusps; usually with tricuspid involvement)
- Rheumatic disease (rare, and essentially never isolated)
- Prosthetic, homograft or conduit stenosis after tetralogy repair, Ross procedure, or pulmonary valve-in-valve implantation
- Supravalvular and branch pulmonary artery stenosis (Williams syndrome, congenital rubella, post-surgical)
- External compression by a dilated aorta, tumour or aneurysm
Technique & pitfalls
- Measure the RVOT diameter in mid-systole from the parasternal short axis, and take the RVOT VTI from the same level.
- Use continuous-wave Doppler for the transvalvular VTI, from both parasternal and subcostal windows.
- Report the Doppler velocity index (RVOT VTI / PV VTI) in prosthetic valves; it is less flow-dependent and less error-prone than the calculated area.[20]
- Distinguish valvular from subvalvular and supravalvular obstruction by pulsed Doppler mapping along the outflow tract and the pulmonary arteries.
- Always interpret against the patient’s own early post-operative baseline in prosthetic and valve-in-valve valves.
- Where the anatomy is complex, CMR and invasive pull-back gradients are the reference, not echo.
Pseudo-change & artefact
- RVOT diameter error, squared — the dominant artefact.
- High-flow states (shunt, anaemia, fever, exercise) raise gradients and can suggest obstruction where none exists.
- Pressure recovery in the compliant pulmonary artery, marked with small conduits and valve-in-valve implants: Doppler gradients routinely exceed catheter gradients.[20]
- Poor parasternal windows; failure to use the subcostal view.
- Contamination by the tricuspid regurgitation jet.
- Distal branch stenosis mimicking valvular obstruction on continuous-wave Doppler.
Treatment thresholds
- Severe valvular pulmonary stenosis (peak gradient >64 mmHg) → balloon pulmonary valvuloplasty, class I for a domed non-dysplastic valve; surgery for dysplastic valves and associated lesions.[25]
- Intervention at lower gradients when there are symptoms, RV dysfunction, right-to-left shunting, or arrhythmia.[25]
- Conduit or prosthetic pulmonary stenosis: rising gradients with a falling Doppler velocity index, particularly with RV dilatation or dysfunction → reintervention, increasingly transcatheter valve-in-valve.[20,25]
- After tetralogy of Fallot repair the intervention decision is driven by pulmonary regurgitation and CMR-derived RV volumes (RVEDVi ≥160 mL/m², RVESVi ≥80 mL/m²), not by valve area.[25]
- No treatment is triggered by a calculated PVA on its own.
Next step
- Next: localise the level of obstruction and quantify pulmonary regurgitation.
- Then: assess RV size, hypertrophy and function; estimate RV systolic pressure from the TR jet.
- Then: CMR for RV volumes and pulmonary regurgitant fraction; CT or angiography for branch and conduit anatomy.
- Then: catheterisation with direct pull-back gradients before intervention.
Drugs
- None. Pulmonary valve stenosis is a mechanical lesion with no medical therapy.
- Correct high-flow states before judging severity.
- Beta-blockers reduce dynamic infundibular obstruction when that is the mechanism.
- Diuretics for right heart congestion.
- Endocarditis prophylaxis for prosthetic and repaired valves.
Reversibility
Excellent, mechanically. Balloon valvuloplasty of a typical domed valve reduces the gradient by 70–90% immediately, with durable long-term results and regression of RV hypertrophy over months to years; the price is progressive pulmonary regurgitation, which becomes the dominant lesion decades later. Dysplastic valves respond poorly to balloon and need surgery. Conduit and prosthetic stenosis is relieved immediately by valve-in-valve or surgical replacement. Nothing regresses spontaneously.[25]