Aortic regurgitation vena contracta

AR VC · Zoomed PLAX (or apical 5-chamber for eccentric jets), narrow colour sector, Nyquist 50–70 cm/s, measured just distal to the flow convergence

Normal range & thresholds

	Mild	Moderate	Severe
Vena contracta width	<0.3 cm	0.3–0.6 cm	>0.6 cm
Jet width / LVOT width	<25%	25–64%	≥65%
EROA	<0.10 cm²	0.10–0.29	≥0.30 cm²
Regurgitant volume	<30 mL	30–59 mL	≥60 mL
Regurgitant fraction	<30%	30–49%	≥50%

Supporting sign of severity: holodiastolic flow reversal in the proximal descending aorta with an end-diastolic velocity >20 cm/s (and, more specifically, in the abdominal aorta).^[4]

Pathophysiology

The vena contracta is the narrowest cross-section of the regurgitant jet, immediately downstream of the orifice. It approximates the effective regurgitant orifice area and, crucially, it is comparatively independent of driving pressure and of flow — unlike jet area, which expands and contracts with blood pressure, machine gain and Nyquist limit. That relative load-independence is why the vena contracta survives as a robust quantitative parameter while colour jet area has been abandoned.^[4,34]

Raised by

Primary cusp disease: bicuspid valve, prolapse, fenestration, endocarditis with perforation, rheumatic retraction, degenerative calcific disease, radiation
Aortic root and STJ disease: annuloaortic ectasia, Marfan and Loeys-Dietz, aortitis, dissection involving the root, hypertension-related root dilatation — these produce a central jet with structurally normal cusps
Ventricular septal defect with cusp prolapse; discrete subaortic membrane with jet-induced cusp damage
Trauma; drug-induced valvulopathy; ankylosing spondylitis and other seronegative arthropathies
Prosthetic and transcatheter valves: paravalvular and transvalvular leak

Lowered by

Successful repair or replacement
Falsely small: an eccentric jet measured in the wrong plane, an inadequate zoom, or a Nyquist limit set too high; hypotension reducing the driving gradient
In acute severe AR the vena contracta may be less impressive than the haemodynamic catastrophe — judge by the ventricle and the clinical picture, not by the width

Technique & pitfalls

Zoom. A vena contracta of 5 mm cannot be measured reliably on a full-sector image — use the narrowest possible colour sector and the highest frame rate.
Identify the three components of the jet — flow convergence, vena contracta, and downstream expansion — and measure at the neck, just distal to the convergence.
Nyquist limit 50–70 cm/s; measure perpendicular to the jet direction.
Eccentric jets (prolapse, perforation) require an off-axis or apical view and are systematically under-measured in the standard PLAX.
Multiple jets are not additive by vena contracta width — go to a volumetric method or 3D vena contracta area.
Record the blood pressure. Grading changes with afterload, and a study performed at 180/100 mmHg over-grades the leak.^[4]

Pseudo-change & artefact

Blood pressure at the time of study — the dominant physiological confounder in both directions.
Inadequate zoom, wide colour sector, low frame rate — all degrade the measurement.
Nyquist limit and colour gain settings.
Eccentric and wall-hugging (Coanda) jets — under-measured on colour, and their area is additionally under-represented.
Multiple jets summed incorrectly.
Prosthetic and transcatheter valves: acoustic shadowing and multiple paravalvular jets make the vena contracta unreliable — use the circumferential extent of the paravalvular leak and TOE instead.^[20]
A very compliant or a very stiff ventricle changing the diastolic gradient without changing the orifice.

Treatment thresholds

Severe AR (vena contracta >0.6 cm with supporting quantitative criteria) plus symptoms → surgery, class I.^[6,7]
Asymptomatic severe AR → surgery for LVEF ≤55% (2025 ESC/EACTS) or ≤50–55% (ACC/AHA); LVESDi >22 mm/m² or LVESVi >45 mL/m² (2025 ESC/EACTS); LVESD >50 mm or >25 mm/m² (2020 ACC/AHA); LVEDD >65 mm (class IIb).^[6,7]
Severe AR undergoing other cardiac surgery → concomitant AVR, class I.^[6,7]
Acute severe AR → urgent surgery, whatever the ventricular dimensions.^[6,7]
Root-driven central AR with normal cusps → valve-sparing root replacement, which both abolishes the leak and treats the aneurysm (cards 02–03).^[9,10]
2025 ESC/EACTS: TAVI may be considered in selected high-risk patients with AR after rigorous Heart Team selection.^[6]

Next step

Next: complete the multiparametric assessment — jet/LVOT ratio, pressure half-time, descending aortic flow reversal, regurgitant volume and fraction, EROA.^[4]
Then: define the mechanism and repairability — TOE with 3D, cusp effective height, STJ and root dimensions.
Then: indexed LV dimensions and volumes, LVEF and GLS; CMR regurgitant fraction when echo is equivocal or the jet is eccentric — it is the most reproducible quantification available.
Then: 6-monthly surveillance once dimensions approach threshold; exercise testing in the ‘asymptomatic’ patient; Heart Team referral before the threshold is crossed.

Drugs

Antihypertensive therapy (ACE inhibitors/ARBs, dihydropyridine calcium blockers) is indicated for coexisting hypertension and modestly reduces regurgitant volume by lowering the diastolic gradient.^[7]
Vasodilators do not defer surgery in asymptomatic severe AR with a dilated ventricle — this was tested and the strategy does not work.^[7,94]
Beta-blockers lengthen diastole and can increase regurgitant volume, but are indicated where there is aortopathy or a syndromic diagnosis.
In acute severe AR, vasodilators and inotropes bridge to surgery; beta-blockade and intra-aortic balloon counterpulsation are contraindicated.
Endocarditis: targeted antibiotics with early surgery for haemodynamic compromise.

Reversibility

The leak is abolished immediately by surgery — and after valve-sparing root replacement for root-driven central AR, freedom from significant recurrent regurgitation is high at 10 years. The reversible component of the ventricle is where the prognosis lies: dimensions fall most in the first 6 months, normalise in the majority when pre-operative LVESD is <50 mm, and rarely normalise above 55 mm; a pre-operative LVEF that is already reduced often fails to recover. Every one of the operative thresholds in this card exists to keep the patient on the reversible side of that line.^[6,94,95]