Echo Reference — Valve Regurgitation
Aortic Regurgitation: Echo Assessment and Grading
Severity criteria for adult native-valve AR, how each measurement is acquired, pressure half-time limitations, what to do when the measurements disagree, acute AR, and current ACC/AHA and ESC 2025 intervention thresholds.
Aortic Regurgitation Severity Criteria
The findings with the greatest specificity for severe AR are a vena contracta (VC) width >6 mm, a central jet width ≥65% of the LV outflow tract (LVOT), holodiastolic flow reversal in the abdominal aorta, and quantitative values in the severe range. Holodiastolic reversal in the proximal descending aorta with an end-diastolic velocity >20 cm/s strongly supports severe AR. A short pressure half-time (PHT) and a dense continuous-wave (CW) signal are supportive only.
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| Parameter | Mild | Moderate | Severe |
|---|---|---|---|
| Valve morphology | Normal or abnormal | Normal or abnormal | Abnormal, flail or wide coaptation defect |
| LV size (chronic AR) | Normal | Normal or dilated | Usually dilated |
| Vena contracta width | <3 mm | 3–6 mm | >6 mm |
| Jet width / LVOT width (central jets) | <25% | 25–64% | ≥65% |
| Flow convergence | None or very small | Intermediate | Large |
| CW signal density | Incomplete or faint | Dense | Dense |
| Pressure half-time | >500 ms | 200–500 ms | <200 ms |
| Descending aorta diastolic flow reversal | Brief, early diastolic | Intermediate | Holodiastolic, end-diastolic velocity >20 cm/s |
| Abdominal aorta diastolic flow reversal | Absent | Usually absent | Holodiastolic |
Sources: ASE 2017 (Zoghbi et al.), EACVI 2022 (Lancellotti et al.) and BSE 2025 (Victor et al.). CW density does not separate moderate from severe AR; an incomplete envelope reflects poor alignment as often as mild AR.
Quantitative Thresholds and the Grade II / III Subdivision
| Parameter | Mild | Mild–moderate (II) | Moderate–severe (III) | Severe |
|---|---|---|---|---|
| EROA (cm²) | <0.10 | 0.10–0.19 | 0.20–0.29 | ≥0.30 |
| Regurgitant volume (mL/beat) | <30 | 30–44 | 45–59 | ≥60 |
| Regurgitant fraction (%) | <30 | 30–39 | 40–49 | ≥50 |
Source: ASE 2017. EROA = effective regurgitant orifice area; RVol = regurgitant volume; RF = regurgitant fraction. Grades II and III are subdivisions of moderate AR, not separate categories.
How the Measurements Are Acquired
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| Parameter | View and technique | Main limitation |
|---|---|---|
| Vena contracta | Zoomed parasternal long-axis (PLAX), narrow colour sector. Narrowest neck of the jet immediately downstream of the regurgitant orifice, between flow convergence and jet expansion, measured perpendicular to the jet direction. | Single-plane width assumes a circular orifice. Less reliable with multiple jets or the elongated orifice of a bicuspid valve; 3D VC area is an adjunct where image quality allows. |
| Jet width / LVOT width | PLAX. Maximal jet width within 1 cm of the valve, as a ratio of LVOT width. | Valid for central jets only. Eccentric jets spread along the septum or anterior mitral leaflet and are underestimated. Gain and Nyquist dependent. |
| Pressure half-time | CW Doppler from apical 5- or 3-chamber, aligned with the jet. Slope of the diastolic deceleration. | Load and LV-compliance dependent (see below). |
| Descending aorta reversal | Suprasternal PW, sample volume in the proximal descending aorta just beyond the left subclavian artery. End-diastolic velocity measured at the R wave. | Reduced aortic compliance (older patients) and other diastolic run-off (patent ductus, AV fistula, ruptured sinus of Valsalva, surgical shunts) produce reversal independent of AR. |
| Abdominal aorta reversal | Subcostal PW in the proximal abdominal aorta. | Specific for severe AR but insensitive; absence does not exclude it. |
| PISA | Apical 5-chamber or PLAX, zoomed, colour baseline shifted in the direction of the jet. Radius measured in early diastole, coaxial with the beam. | Non-hemispheric convergence, constrained by the aortic wall or cusps, can under- or overestimate EROA depending on its geometry. A distorted convergence zone may make PISA unreliable, and angle correction does not always rescue it. Difficult with eccentric jets. |
| Volumetric method | RVol = LVOT stroke volume minus forward stroke volume at a non-regurgitant site (mitral annulus or RVOT). Alternatively, LV total stroke volume (3D EDV − ESV) minus that same non-regurgitant forward stroke volume — not the LVOT stroke volume, which in AR already includes the regurgitant volume. | LVOT diameter error is squared, and echo tends to underestimate LV volumes. The mitral reference is invalid with more than mild MR; the RVOT reference is invalid with significant PR or an intracardiac shunt. |
| LV size and volumes | LVEDD and LVESD from PLAX; LV volumes by biplane or, preferably, 3D. Index to BSA. | Linear dimensions miss non-spherical remodelling. Foreshortened apical views underestimate volumes. |
Pressure Half-Time: Interpretation and Limitations
PHT measures how quickly aortic and LV diastolic pressures equalise. Severe AR shortens it, but so does anything that raises LV diastolic pressure or reduces LV compliance: coexisting LV dysfunction, restrictive physiology, LV hypertrophy and acute AR. Vasodilators shorten it by a different route — lower systemic vascular resistance makes aortic diastolic pressure fall faster. In the other direction, a compliant, dilated LV in chronic compensated AR and a high systemic vascular resistance both prolong PHT despite significant regurgitation.
Distinguishing AR from MR on Continuous-Wave Doppler
Both produce high-velocity CW signals from the apical windows. On a conventional apical recording, AR flows toward the transducer in diastole and appears above the baseline. MR flows away from the transducer in systole and appears below it. Timing against the ECG, the valve of origin on 2D/colour, and beam direction are more reliable than the display, which can be inverted.
Quantification Formulas and a Worked Example
| Step | As measured | LVOT overmeasured by 2 mm |
|---|---|---|
| LVOT diameter / VTI | 2.2 cm / 30 cm | 2.4 cm / 30 cm |
| SVLVOT | 114 mL | 136 mL |
| SVmitral (annulus 3.2 cm, VTI 8.0 cm) | 64 mL | 64 mL |
| Regurgitant volume | 50 mL | 71 mL |
| Regurgitant fraction | 44% | 53% |
| EROA (VTIAR 200 cm) | 0.25 cm² | 0.36 cm² |
| Grade | Moderate–severe (III) | Severe |
A 2 mm LVOT error reclassifies the same patient. Volumetric results should agree with the qualitative and semi-quantitative findings before they are reported as definitive.
Practical Assessment Pathway
The pathway below is adapted from the ASE 2017 integrative approach and the BSE 2025 decision aid. BSE confirms a grade when at least one quantitative or qualitative criterion, one corroborative finding and the indexed LV size all agree.
Yes
No — more than mild
Concordant
Discordant or technically limited
When AR Measurements Disagree
Discordance is common and is usually technical or haemodynamic rather than a true intermediate grade. The patterns below account for most cases.
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| Pattern | Likely explanation | What to check |
|---|---|---|
| Short PHT, but small VC and no holodiastolic reversal | Raised LV diastolic pressure, reduced LV compliance or vasodilatation rather than severe AR | LV filling pressure, LV hypertrophy, blood pressure, medications; consider acute AR if clinically suspected |
| Long PHT, but large VC or severe quantitation | Compliant, dilated LV in chronic AR; high systemic vascular resistance | Rely on VC, flow reversal and quantitation; note blood pressure |
| Wide jet, but narrow VC | Jet spreading within the LVOT, measurement too far below the valve, high colour gain or low Nyquist limit | Remeasure jet width within 1 cm of the valve; reduce gain |
| Small-looking jet, but holodiastolic reversal and dilated LV | Eccentric jet (cusp prolapse, bicuspid valve) underestimated by width and area | VC in multiple views and quantitation; 3D VC area as an adjunct if image quality allows; CMR if still unresolved |
| Holodiastolic reversal, but other parameters mild–moderate | Stiff aorta or another source of diastolic run-off | End-diastolic velocity, abdominal aortic flow, patent ductus or other shunt |
| Severe quantitation, but normal LV size | LVOT diameter overmeasurement, acute AR, early disease, or small body size | LVOT diameter, indexed LV volumes, time course; CMR |
| PISA and volumetric results disagree | MR invalidating the mitral reference, squared LVOT error, non-hemispheric flow convergence | Use the RVOT as reference if there is no significant PR or shunt; review the convergence geometry; CMR |
Choosing Additional Imaging: TOE, CMR and CT
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| Modality | Question it answers | Typical indication |
|---|---|---|
| TOE | Mechanism: cusp number, prolapse, perforation, vegetation or abscess, dissection flap, repair feasibility; 3D VC area where feasible | Suspected endocarditis or dissection, uncertain mechanism, repair planning, poor transthoracic windows |
| CMR | Reproducible RVol and RF by phase-contrast flow in the proximal ascending aorta; LV volumes and EF; myocardial fibrosis | Discordant or borderline grading; LV volumes near intervention thresholds; serial follow-up when echo reproducibility is limited |
| CT | Aortic root and ascending aorta dimensions, cusp morphology and calcification, coronary anatomy, transcatheter planning | Associated aortopathy, discrepant echo aortic measurements, pre-operative planning |
| Exercise testing | True symptom status and functional capacity | Equivocal symptoms in apparently asymptomatic severe AR |
CMR thresholds are not interchangeable with echo thresholds. In one cohort, a CMR regurgitant fraction >33% predicted progression to surgery (Myerson et al., 2012).
Valve Mechanism and Aortic Root Assessment
Mechanism determines how reliably each parameter performs, the likely aetiology, and whether repair is possible. The repair-oriented functional classification groups AR into type I (normal cusp motion with aortic dilatation or cusp perforation), type II (cusp prolapse) and type III (cusp restriction).
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| Finding | Echo features | Relevance |
|---|---|---|
| Cusp number | Bicuspid (raphe, fusion pattern), unicuspid or quadricuspid valve | Eccentric jets; associated aortopathy |
| Aortic dilatation (type I) | Root, sinotubular junction or ascending aorta dilatation with normal cusp motion and a central jet | Aortic dimensions may set intervention timing |
| Perforation (type I) | Jet arising through the cusp body rather than the coaptation line | Endocarditis until proven otherwise |
| Prolapse (type II) | Cusp free edge below the annular plane; jet directed away from the prolapsing cusp | Eccentric jet underestimated by width; often repairable |
| Restriction (type III) | Thickened, calcified or retracted cusps — degenerative, rheumatic, post-radiation or drug-related | Less suited to repair |
Aortic root dilatation can cause AR through functional annular dilatation, or accompany it through a shared aortopathy such as bicuspid valve disease or heritable thoracic aortic disease. Report the annulus, sinus of Valsalva, sinotubular junction and ascending aorta whenever AR is present. In patients with AR and aortic dilatation, the aortic dimension may determine the timing of surgery independently of AR severity. See Aortic Dimensions for sex-specific and indexed reference values.
Acute Severe Aortic Regurgitation
| Feature | Chronic severe AR | Acute severe AR |
|---|---|---|
| LV size | Dilated (eccentric remodelling) | Normal or mildly dilated |
| LV function | Preserved until decompensation | Hyperdynamic early, then deteriorates rapidly |
| Pressure half-time | Variable; may be long if the LV is compliant | Very short |
| Colour jet | Usually large and holodiastolic | Short duration; may look small |
| Aortic flow reversal | Holodiastolic | May end before end-diastole as pressures equalise |
| Mitral valve | Normal timing | Premature closure and/or diastolic MR |
| Typical causes | Bicuspid valve, degenerative disease, aortic dilatation | Endocarditis, type A dissection, trauma, iatrogenic |
Premature mitral valve closure (closure before the onset of the QRS on M-mode) and diastolic MR are distinct findings. Both reflect LV pressure exceeding left atrial pressure during diastole, before ventricular systole. Diastolic MR is also seen with a long PR interval, AV block and markedly raised filling pressure from other causes, so neither finding is pathognomonic. In the context of acute AR, both indicate a severely raised LV diastolic pressure.
Mixed Aortic Valve Disease and Coexisting MR
AR increases systolic flow across the aortic valve. In mixed disease, peak velocity and mean gradient therefore rise for any given valve area and reflect the combined haemodynamic load. The continuity-equation valve area remains valid because the LVOT and transaortic velocity-time integrals are both systolic. ESC/EACTS 2025 and ACC/AHA 2020 set the same Class I criteria for intervention in mixed moderate AS and AR, even when the valve area is >1.0 cm²:
| Mixed moderate AS and AR | Intervention criterion (Class I) |
|---|---|
| Symptomatic | Mean gradient ≥40 mmHg or Vmax ≥4.0 m/s |
| Asymptomatic, LVEF <50% not explained by other cardiac disease | Vmax ≥4.0 m/s |
Sources: Praz et al., 2025 ESC/EACTS guideline; Otto et al., 2020 ACC/AHA guideline. Outside these criteria, management follows the predominant lesion. See Aortic Stenosis for stenosis grading and low-flow assessment.
The stenotic component also distorts AR assessment. LV hypertrophy reduces compliance, which shortens PHT and limits LV dilatation, so these two markers are less reliable in mixed disease. Coexisting MR invalidates the mitral-referenced volumetric method; use the RVOT as the forward reference if there is no significant PR or shunt, or PISA.
LV Response and Follow-up Intervals
Chronic AR imposes combined volume and pressure overload, producing eccentric hypertrophy and progressive dilatation. LV enlargement beyond sex-specific normal limits supports the grade but is not a diagnostic cut-off on its own. Report LVEDD, LVESD and LVESD indexed to BSA, indexed LV volumes (3D preferred), LVEF, and global longitudinal strain where reproducible. Normal ranges are on LV Volumes & Ejection Fraction and LV Dimensions & Mass.
A normal-sized LV makes chronic severe AR unlikely and should prompt a recheck of the severity measurements. The exceptions are acute AR, small body size (hence indexing), and concentric remodelling from hypertension or coexisting aortic stenosis. Serial change matters as much as absolute values, so compare with the previous study directly, ideally side by side.
| Asymptomatic AR with normal LV function | Typical echo interval |
|---|---|
| Mild | 3–5 years |
| Moderate | 1–2 years |
| Severe | 6–12 months |
| Severe, with progressive LV change or values approaching thresholds | 3–6 months |
ACC/AHA 2020 intervals; 3–6-month review for severe AR approaching thresholds per ESC/EACTS. Reassess earlier with new symptoms or clinical change.
Echo Triggers for Intervention in Chronic Severe AR
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| Asymptomatic severe AR | ACC/AHA 2020 | ESC/EACTS 2025 |
|---|---|---|
| Reduced LVEF | LVEF ≤55% without another cause — Class I | LVEF ≤50% — Class I |
| Severe LV dilatation | LVESD >50 mm or LVESDi >25 mm/m² — Class IIa | LVESD >50 mm or LVESDi >25 mm/m² — Class I |
| Earlier intervention, low surgical risk | Progressive LVEF decline to 55–60% on ≥3 studies, or progressive dilatation to LVEDD >65 mm — Class IIb | LVEF ≤55%, LVESDi >22 mm/m² or LVESVi >45 mL/m² (especially BSA <1.68 m²) — Class IIb |
| Other cardiac surgery planned | Severe AR — Class I; moderate AR — Class IIa | Severe AR — Class I |
Sources: Otto et al., 2020 ACC/AHA guideline; Praz et al., 2025 ESC/EACTS guideline. LVESDi = LVESD indexed to BSA; LVESVi = LV end-systolic volume indexed to BSA. ESC 2025 also upgrades valve repair in experienced centres (Class IIa) and allows TAVI with dedicated devices for symptomatic patients ineligible for surgery (Class IIb).
Global longitudinal strain, natriuretic peptides, CMR fibrosis and exercise capacity are supplementary markers. Impaired or declining values identify higher-risk patients in observational cohorts and can support earlier review in borderline cases, but none has a guideline-endorsed AR-specific intervention threshold.
AR Reporting Checklist
| Element | What to report |
|---|---|
| Mechanism | Cusp number, prolapse, restriction or perforation; root involvement |
| Integrated severity | Mild, moderate (grade II or III) or severe — not a single parameter |
| Supporting measurements | VC, central jet width, PHT, flow reversal with end-diastolic velocity, EROA/RVol/RF with the method used |
| LV response | LVEDD, LVESD, LVESDi, indexed volumes, LVEF; GLS if reproducible |
| Aorta | Annulus, sinus of Valsalva, sinotubular junction and ascending aorta |
| Comparison | Change from the previous study, ideally reviewed side by side |
| Conditions and limitations | Blood pressure, heart rate and rhythm, image quality, discordant parameters |
Frequently Asked Questions
How is severe aortic regurgitation defined on echocardiography?
By integrating several parameters rather than relying on one. The most specific findings are a vena contracta >6 mm, a central jet width ≥65% of the LVOT, holodiastolic flow reversal in the abdominal aorta, and quantitative values of EROA ≥0.30 cm², regurgitant volume ≥60 mL or regurgitant fraction ≥50%. In chronic AR, LV dilatation should support the grade.
Is pressure half-time reliable for grading aortic regurgitation?
Only as a supportive sign. PHT shortens with severe AR but also with raised LV diastolic pressure, reduced LV compliance and LV hypertrophy, and with vasodilators through lower systemic vascular resistance. It lengthens with a compliant, dilated LV and with high systemic vascular resistance. It should never be used in isolation.
Why are eccentric AR jets underestimated?
An eccentric jet, typically from cusp prolapse or a bicuspid valve, hugs the septum or anterior mitral leaflet, so its width and area understate the regurgitant volume. Vena contracta in more than one view, 3D vena contracta area, aortic flow reversal and quantitation are more reliable. CMR helps when these remain inconclusive.
Can aortic regurgitation be severe if the left ventricle is normal in size?
In acute AR, yes; the ventricle has not had time to dilate. In chronic AR, a normal-sized LV makes severe regurgitation unlikely and should prompt a recheck of the measurements, allowing for small body size and concentric remodelling from hypertension or coexisting aortic stenosis.
When does cardiac MRI help in aortic regurgitation?
When echo parameters are discordant or technically limited, when LV volumes are close to intervention thresholds, and for reproducible serial follow-up. CMR measures regurgitant volume and fraction directly by phase-contrast flow and provides accurate LV volumes, but its thresholds are not interchangeable with echo thresholds.
How often should aortic regurgitation be re-scanned?
For asymptomatic patients with normal LV function, typically every 3–5 years for mild AR, every 1–2 years for moderate AR and every 6–12 months for severe AR. Severe AR with progressive LV change or values approaching intervention thresholds warrants review every 3–6 months, and any new symptoms warrant earlier reassessment.
Related Echocardiography References
References
- Zoghbi WA, Adams D, Bonow RO, 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. doi:10.1016/j.echo.2017.01.007
- Victor K, Ring L, Tsampasian V, et al. Echocardiographic assessment of aortic regurgitation: a practical guideline from the British Society of Echocardiography. Echo Res Pract. 2025;12(1):3. doi:10.1186/s44156-024-00067-8
- Lancellotti P, Pibarot P, Chambers J, et al. Multi-modality imaging assessment of native valvular regurgitation: an EACVI and ESC Council of Valvular Heart Disease position paper. Eur Heart J Cardiovasc Imaging. 2022;23(5):e171–e232. doi:10.1093/ehjci/jeab253
- Praz F, Borger MA, et al. 2025 ESC/EACTS Guidelines for the management of valvular heart disease. Eur Heart J. 2025;46(44):4635–4736. doi:10.1093/eurheartj/ehaf194
- Otto CM, Nishimura RA, Bonow RO, et al. 2020 ACC/AHA Guideline for the management of patients with valvular heart disease. Circulation. 2021;143(5):e72–e227. doi:10.1161/CIR.0000000000000923
- Myerson SG, d'Arcy J, Mohiaddin R, et al. Aortic regurgitation quantification using cardiovascular magnetic resonance: association with clinical outcome. Circulation. 2012;126(12):1452–1460. doi:10.1161/CIRCULATIONAHA.111.083600