Echo Reference — Valve Regurgitation
Aortic Regurgitation
Qualitative and quantitative severity grading with 4-grade thresholds. Pressure half-time, vena contracta, descending aorta flow reversal, and ASE integration algorithm for chronic AR.
Qualitative & Semi-Quantitative Parameters
AR severity is graded by integrating multiple Doppler and colour flow parameters. The most specific signs of severe AR are holodiastolic flow reversal in the descending aorta, a short pressure half-time (< 200 ms), and a wide vena contracta (≥ 6 mm). Colour jet width relative to LVOT is useful for screening but is influenced by machine settings.
| Parameter | Mild | Moderate | Severe |
|---|---|---|---|
| Colour jet width / LVOT width (%) | < 25 | 25 – 64 | ≥ 65 |
| Vena contracta width (mm) | < 3 | 3 – 5.9 | ≥ 6 |
| CW Doppler signal density | Faint, incomplete | Dense, incomplete envelope | Dense, complete envelope with steep deceleration slope |
| Pressure half-time (ms) | > 500 | 200 – 500 | < 200 |
| Descending aorta flow reversal | Brief, early diastolic | Intermediate | Holodiastolic |
| Abdominal aorta flow reversal | Absent | Absent or brief | Holodiastolic |
PHT interpretation caveats: Pressure half-time reflects the rate of equalisation between aortic and LV diastolic pressures. A short PHT (< 200 ms) indicates rapid equalisation — consistent with severe AR, but also seen in acute AR (where LV compliance is low) and with elevated LV end-diastolic pressure from any cause. A long PHT does not exclude severe AR if LV compliance is high (chronic, well-compensated AR). PHT should never be used in isolation.
Descending aorta reversal: Sample with PW Doppler in the proximal descending aorta from the suprasternal view. Holodiastolic reversal with an end-diastolic velocity ≥ 20 cm/s is highly specific for at least moderate AR. Abdominal aorta holodiastolic reversal (from the subcostal view) is even more specific for severe AR but is less sensitive.
Quantitative Parameters
| Parameter | Mild | Moderate | Moderate–Severe | Severe |
|---|---|---|---|---|
| EROA (cm²) | < 0.10 | 0.10 – 0.19 | 0.20 – 0.29 | ≥ 0.30 |
| RVol (mL/beat) | < 30 | 30 – 44 | 45 – 59 | ≥ 60 |
| Regurgitant fraction (%) | < 30 | 30 – 39 | 40 – 49 | ≥ 50 |
Quantification methods: EROA and RVol can be calculated by PISA (less commonly applied to AR due to the diastolic timing and often eccentric jet geometry) or by the volumetric method (comparing aortic SV by LVOT Doppler with mitral SV by mitral annular Doppler — the difference is the regurgitant volume). The volumetric method is preferred for AR quantification but requires accurate LVOT and mitral annular measurements and is invalid with coexisting significant MR.
Integration Algorithm — Chronic AR
| Step | Action |
|---|---|
| 1. Screen | Colour jet width relative to LVOT in parasternal long-axis view. Narrow jet (< 25% LVOT) → likely mild. Wide jet (≥ 65% LVOT) → likely severe. Intermediate → proceed. |
| 2. Semi-quantify | Vena contracta width (parasternal long-axis, zoom). VC < 3 mm → mild. VC ≥ 6 mm → severe. VC 3–5.9 mm → proceed to quantitative methods and supportive signs. |
| 3. Supportive signs | CW Doppler: PHT (< 200 ms → severe, > 500 ms → mild). Descending aorta: holodiastolic reversal → at least moderate. Abdominal aorta holodiastolic reversal → severe. |
| 4. Quantify | Volumetric method: RVol = SVLVOT − SVMitral. Calculate EROA from RVol ÷ AR VTI. Apply 4-grade thresholds. |
| 5. LV response | LV size and function. Chronic severe AR → LV dilatation (LVEDVi > 75 mL/m² in women, > 85 mL/m² in men). A normal-sized LV argues against chronic severe AR (unless acute). |
Clinical Context
Acute vs Chronic AR
| Feature | Chronic Severe AR | Acute Severe AR |
|---|---|---|
| LV size | Dilated (compensatory eccentric remodelling) | Normal or mildly dilated |
| LV EF | Normal or reduced (decompensated) | Hyperdynamic early, then rapidly deteriorates |
| PHT | Variable (may be long if LV compliant) | Very short (< 200 ms) — rapid LV pressure rise |
| Colour jet | Often large | May be deceptively small (high LVEDP reduces driving gradient) |
| Mitral valve | Normal opening | Premature mitral valve closure (diastolic MR) — pathognomonic of acute severe AR with markedly elevated LVEDP |
| Aetiology | Bicuspid valve, degenerative, chronic aortopathy | Endocarditis, aortic dissection, trauma |
Premature MV closure: In acute severe AR, the rapid rise in LVEDP may exceed LA pressure before atrial systole, causing the mitral valve to close before the QRS — premature mitral valve closure on M-mode. This is a critical sign indicating haemodynamic emergency and the need for urgent surgical intervention.
Measurement Pitfalls
| Pitfall | Impact |
|---|---|
| Jet width measured in wrong plane | Jet width/LVOT ratio must be measured in the parasternal long-axis view immediately below the valve. Apical views foreshorten the jet and overestimate severity. |
| Eccentric jets | Eccentric AR jets (e.g. from a bicuspid valve or prolapsing cusp) are underestimated by jet width. Vena contracta and quantitative methods are essential for eccentric jets. |
| Confusing AR and MR on CW Doppler | Both produce high-velocity signals in the apical view. AR is diastolic (below baseline); MR is systolic (above baseline). Use timing and spectral shape to differentiate. |
| PHT with elevated LVEDP | Any cause of elevated LVEDP (including coexisting LV dysfunction, restrictive physiology) shortens PHT independent of AR severity. A short PHT does not always mean severe AR. |
| Colour gain too high | Excessive colour gain overestimates jet width and area. Reduce gain until background noise just disappears before measuring. |
| Coexisting AS | In mixed aortic valve disease, AS increases transaortic flow which inflates AR gradients and jet width. Quantitative methods (EROA, RVol) better isolate AR severity from the stenotic component. |
Aortic Root Assessment
Always report aortic root and ascending aorta dimensions when AR is identified. Aortic root dilatation is both a cause and a consequence of AR. In patients with significant AR and aortopathy, the threshold for surgical intervention may be determined by the aortic dimensions rather than the AR severity alone. See Aortic Dimensions for BSA-indexed and height-indexed reference values.
Echo Triggers for Surgical Referral — Asymptomatic Severe AR
In asymptomatic patients with chronic severe AR, the following echocardiographic parameters are used to guide the timing of surgical referral. These thresholds indicate LV decompensation or remodelling that warrants intervention before irreversible myocardial damage occurs.
| Parameter | ACC/AHA 2020 | ESC/EACTS 2021 |
|---|---|---|
| LVEF | ≤ 55% (Class I) | < 55% or declining (even if still > 55%) |
| LVESD | > 50 mm (Class I) | > 50 mm (or > 25 mm/m² BSA-indexed) |
| LVEDd | > 65 mm (Class IIa — may be considered) | > 70 mm (or > 35 mm/m² indexed) |
| LV volumes (3D/CMR) | LVESVi > 45 mL/m² (supplementary) | Progressive LV dilatation on serial imaging |
Key principles: LVESD > 50 mm and LVEF ≤ 55% are the strongest and most consistently endorsed triggers across both ACC/AHA and ESC guidelines. LVEDd thresholds are less robust — ACC/AHA considers > 65 mm a Class IIa trigger, while ESC uses > 70 mm. Serial change matters as much as absolute values — a declining LVEF or progressive LV dilatation should prompt earlier referral even if individual thresholds have not been crossed. In patients with small body habitus, BSA-indexed values (LVESD > 25 mm/m²) should be used.
Supplementary markers: GLS decline (> 2 percentage point reduction from baseline) may detect early subclinical LV dysfunction before EF drops below 55%. BNP elevation and reduced exercise capacity on stress testing are non-echo triggers that also support earlier intervention. These are particularly useful in the "watchful waiting" phase when EF is 55–60% and dimensions are borderline.
References
- Zoghbi WA, et al. Recommendations for Noninvasive Evaluation of Native Valvular Regurgitation: A Report from the American Society of Echocardiography. J Am Soc Echocardiogr. 2017;30(4):303–371.
- Otto CM, et al. 2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease. Circulation. 2021;143(5):e72–e227.
- Vahanian A, et al. 2021 ESC/EACTS Guidelines for the Management of Valvular Heart Disease. Eur Heart J. 2022;43(7):561–632.