Aortic Regurgitation

RDCS Adult Echocardiography AE

Track your progress as you read

Finished sections get a check mark.

1 Introduction & Exam Overview

The RDCS AE Exam, SPI Requirement & Logistics Content Outline, Domain Weights & How to Study

2 Cardiac Anatomy

Chambers, Walls, Myocardial Layers & the 17-Segment Model Cardiac Valves & Subvalvular Apparatus Great Vessels, Pericardium, Coronary & Venous Anatomy

3 Cardiac Physiology & Hemodynamics

Cardiac Cycle, Phases & Pressure-Volume Relationships Normal Systolic & Diastolic Function Hemodynamic Principles & Response to Stress

4 Echo Modalities, Instrumentation & Contrast

2D (B-Mode) and M-Mode Imaging Spectral, Color, and Tissue Doppler Modalities Image Optimization, Artifacts, and Contrast Echocardiography

5 Standard Views, Windows & Protocol

Parasternal Long- & Short-Axis Views Apical Views Subcostal & Suprasternal-Notch Views Exam Protocol, Patient Positioning & Provocative Maneuvers

6 Quantification & Doppler Hemodynamic Calculations

Chamber Quantification: LV, LA, RA, and RV Size, Mass, and Volumes Systolic Function: Ejection Fraction Methods, Fractional Shortening & Strain Diastolic Function Grading (ASE/EACVI 2016) Core Doppler Math: Modified Bernoulli, VTI, Stroke Volume & the Continuity Equation Advanced Hemodynamics: PISA/EROA, Pressure Half-Time, dP/dt, Qp/Qs & RVSP

7 Aortic & Mitral Valve Disease

Aortic Stenosis Aortic Regurgitation Mitral Stenosis Mitral Regurgitation

8 Right-Sided, Prosthetic & Infective Valve Disease

Tricuspid & Pulmonic Valve Disease and Pulmonary Hypertension Assessment Infective Endocarditis and Vegetations Prosthetic Valves and Postoperative Evaluation

9 Ischemic Disease & Cardiomyopathies

Coronary Anatomy, Ischemic Heart Disease & Wall-Motion Abnormalities Stress Echocardiography & Myocardial Viability Mechanical Complications of Myocardial Infarction Dilated & Restrictive Cardiomyopathy Hypertrophic Cardiomyopathy, SAM & LVOT Obstruction

10 Pericardial Disease, Masses & Aorta

Pericardial Effusion & Cardiac Tamponade Constrictive Pericarditis vs. Restrictive Physiology Cardiac Masses, Tumors & Thrombi Aortic Disease: Aneurysm, Dissection & Atheroma

11 Congenital Heart Disease & Shunts

Septal Defects & Shunt Quantification Common Adult Congenital Lesions

12 Clinical Care & Safety

Patient Care, Clinical-Data Integration & Exam Protocols Bioeffects, ALARA, Infection Control & Ergonomics

Aortic Regurgitation

Key Takeaways Explain This Topic AI

Severe aortic regurgitation is characterized by a vena contracta width ≥0.6 cm (6 mm), pressure half-time <200 ms, and holodiastolic flow reversal in the descending aorta.

A regurgitant jet occupying ≥65% of the LVOT width on color Doppler indicates severe AR.

Quantitative severe AR criteria include an effective regurgitant orifice area ≥0.30 cm², regurgitant volume ≥60 mL/beat, and regurgitant fraction ≥50%.

An end-diastolic flow velocity ≥20 cm/s in the descending aorta is highly specific for at least moderate aortic regurgitation.

Acute severe AR causes rapid LV diastolic pressure equalization with the aorta and premature mitral valve closure, producing a short pressure half-time even without chronic compensatory LV dilation.

Last updated: July 2026

Aortic Regurgitation: Etiology

Aortic regurgitation (AR) arises from either primary leaflet disease or secondary aortic root/annular disease , and often a combination of both.

Primary (valvular): bicuspid aortic valve, infective endocarditis (leaflet destruction or perforation), rheumatic disease, myxomatous degeneration, and iatrogenic causes (post-TAVR, post-balloon valvuloplasty).

Secondary (root-based): aortic root dilation prevents leaflet coaptation despite structurally normal leaflets — annuloaortic ectasia, Marfan syndrome and other connective-tissue disease, aortic dissection, chronic hypertension, and aortitis.

The distinction matters clinically: root-based AR may be treated with valve-sparing aortic root replacement rather than valve replacement.

Severity Grading

As with AS, AR severity uses an integrated multiparametric approach combining color Doppler jet characteristics, spectral Doppler, descending-aorta flow patterns, and quantitative PISA-derived volumetric parameters:

• Parameter Mild Moderate Severe
• Jet width / LVOT width (%) <25 25–64 ≥65
• Vena contracta width (cm) <0.3 0.3–0.59 ≥0.6
• Pressure half-time (ms) >500 200–500 <200
• Descending aorta diastolic flow reversal brief, early diastolic intermediate holodiastolic
• Effective regurgitant orifice area (cm²) <0.10 0.10–0.29 ≥0.30
• Regurgitant volume (mL/beat) <30 30–59 ≥60
• Regurgitant fraction (%) <30 30–49 ≥50

The most specific signs of severe AR are a wide vena contracta (≥0.6 cm), a short pressure half-time (<200 ms), and holodiastolic flow reversal in the descending thoracic aorta on pulsed-wave Doppler. An end-diastolic flow velocity ≥20 cm/s in the descending aorta is highly specific for at least moderate AR; the same finding recorded in the more distal abdominal aorta raises specificity further and is a hallmark of severe AR.

Pressure half-time reflects how quickly the aortic-to-LV diastolic pressure gradient equalizes: the more severe the regurgitation, the faster LV pressure rises to meet aortic pressure, and the shorter the PHT. Because PHT is also shortened by any process that raises LV diastolic pressure independent of AR severity (reduced LV compliance, concurrent AS, or acute decompensation), it should never be used in isolation.

Jet Geometry Pitfalls

Color Doppler jet width and jet area are the least reliable AR parameters because eccentric jets — common with bicuspid valves or leaflet prolapse — hug the LVOT wall (Coanda effect) and visually underestimate severity relative to their true volumetric regurgitant flow. Vena contracta width, measured just below the coaptation point in the LVOT, is less angle- and flow-dependent and is preferred over jet area for semiquantitative grading. When feasible, the PISA method can also be applied to the AR jet to calculate EROA and regurgitant volume, analogous to its use in mitral regurgitation (Section 7.4).

Additional Echocardiographic Signs

The parasternal short-axis view of the aortic valve can localize the jet's origin at the coaptation defect — a central jet suggests root dilation or a symmetric leaflet process, while a commissural or eccentric jet points to a focal leaflet abnormality such as a bicuspid valve, prolapse, or endocarditis-related perforation, and should prompt closer structural evaluation of that leaflet segment. A classic, though nonspecific, M-mode finding in significant AR is fine diastolic fluttering of the anterior mitral leaflet (and sometimes the interventricular septum), produced by the regurgitant jet striking the leaflet; its presence supports at least moderate AR but its absence does not exclude it, so it is never used as a standalone severity criterion.

Acute vs. Chronic Severe AR

The hemodynamic tolerance of severe AR differs dramatically by time course:

Chronic severe AR: the LV has time to dilate and hypertrophy (eccentric hypertrophy), maintaining forward stroke volume at a normal end-diastolic pressure for years; patients may remain asymptomatic despite severe AR. LV end-systolic dimension and ejection fraction are the key trending parameters that trigger surgical timing even before symptoms develop.

Acute severe AR (endocarditis, dissection, trauma): the non-dilated, non-compliant LV cannot accommodate the sudden regurgitant volume, so LV diastolic pressure rises rapidly, closing the mitral valve prematurely ( premature MV closure ) and producing a very short PHT with low cardiac output — a surgical emergency, even though chronic quantitative volume criteria may not be met.

LV Size and Function as Intervention Triggers

Because chronic severe AR can remain asymptomatic for years while progressively remodeling the LV, serial trending of LV end-systolic dimension (LVESD) and ejection fraction is central to timing intervention before irreversible LV dysfunction develops. Per current ACC/AHA guidance, intervention is indicated for severe chronic AR when LVEF falls to ≤55% or symptoms develop (both are strong indications), and is also reasonable once LVESD exceeds 50 mm (or an indexed LVESD >25 mm/m² in patients of small body size) even in the absence of symptoms or LVEF decline. These thresholds make serial 2D or 3D LV volumetric and M-mode/2D linear-dimension measurements — not a single-visit gradient or vena contracta — the parameters that most directly drive the timing of aortic valve intervention in chronic severe AR.

Key Testing Points

Severe AR = vena contracta ≥0.6 cm, PHT <200 ms, holodiastolic descending aorta flow reversal — the three most specific signs.

Quantitative severe AR = EROA ≥0.30 cm², regurgitant volume ≥60 mL/beat, regurgitant fraction ≥50%.

Jet width/area is the least reliable sign because eccentric jets underestimate severity.

Premature mitral valve closure with a short PHT in a non-dilated LV suggests acute, poorly tolerated severe AR.