AVA (Continuity Equation)

AVA (Continuity Equation): Calculates aortic valve area from Doppler echocardiography to assess aortic stenosis severity.

Doppler & Valve Measurements

LVOT Diameter (measured at base in systole)

LVOT VTI (from pulsed-wave Doppler)

Aortic Valve VTI (from continuous-wave Doppler)

Body Surface Area (for indexing)

Formula

AVA = (π/4 × LVOT d2) × (VTI_LVOT / VTI_AV)

Guidelines & Evidence

Verified

Last Review: 2026-07-17

When to Use

Quantification of aortic stenosis severity on TTE/TEE

Decision-making for AVR vs. conservative management

Diagnostic workup of murmurs

Serial assessment of severe AS progression

Discordant gradient/area findings (low-flow states)

Key Points

Recommended by ACC/AHA and ESC guidelines as gold standard for AS quantification

More reliable than simpler planimetered area in off-axis imaging

Critical in low-gradient AS scenarios for true area determination

Requires good image quality (LVOT visualization + aortic valve alignment)

How it Works

Formula

AVA = (π/4 × LVOT diameter2) × (LVOT VTI / Aortic Valve VTI) Simplified: AVA = (π/4 × LVOT d2) × (V1 / V2) Where d = LVOT diameter (parasternal long axis), VTI = velocity-time integral (PWD or CWD)

Severity Classification (Aortic Stenosis)

AVA (cm2)	Mean Gradient (mmHg)	Classification
>1.5	<25	Mild
1.0–1.5	25–40	Moderate
<1.0	>40	Severe
<0.6	Variable	Very Severe (operative threshold)

Last Comprehensive Review: 2026-07-17

Guidelines & Evidence

Verified

Last Review: 2026-07-17

When to Use

Quantification of aortic stenosis severity on TTE/TEE

Decision-making for AVR vs. conservative management

Diagnostic workup of murmurs

Serial assessment of severe AS progression

Discordant gradient/area findings (low-flow states)

Key Points

Recommended by ACC/AHA and ESC guidelines as gold standard for AS quantification

More reliable than simpler planimetered area in off-axis imaging

Critical in low-gradient AS scenarios for true area determination

Requires good image quality (LVOT visualization + aortic valve alignment)

How it Works

Formula

Severity Classification (Aortic Stenosis)

AVA (cm2)	Mean Gradient (mmHg)	Classification
>1.5	<25	Mild
1.0–1.5	25–40	Moderate
<1.0	>40	Severe
<0.6	Variable	Very Severe (operative threshold)

Last Comprehensive Review: 2026-07-17

Recent Journal Updates

JAMAJul 21, 2026

US Food Swamps Have Increased as Food Deserts Remain Static

Clinical Context

We think this might be relevant to the clinical guidance for Aortic Valve Area (Continuity Equation).

WHO NewsJul 20, 2026

Road deaths fall by 21% globally but stronger action is needed to save lives

Clinical Context

We think this might be relevant to the clinical guidance for Aortic Valve Area (Continuity Equation).

FDA MedWatchJul 13, 2026

Pulmonary Valve Catheter Delivery System Recall: Medtronic Removes Harmony Delivery Catheter System (DCS)

Clinical Context

We think this might be relevant to the clinical guidance for Aortic Valve Area (Continuity Equation).

AVA (Continuity Equation)

When to Use

When to Use

Key Points

How it Works

Formula

Severity Classification (Aortic Stenosis)

Clinical Pearls

Technical Considerations

Clinical Pearls

Next Steps

Mild AS (AVA >1.5 cm2)

Moderate AS (AVA 1.0–1.5 cm2)

Severe AS (AVA <1.0 cm2)

Complementary Calculators

The Evidence

Validation

ESC/EACTS Guidelines for the management of valvular heart disease.

2014 AHA/ACC Guideline for the Management of Patients With Valvular Heart Disease.

When to Use

When to Use

Key Points

How it Works

Formula

Severity Classification (Aortic Stenosis)

Clinical Pearls

Technical Considerations

Clinical Pearls

Next Steps

Mild AS (AVA >1.5 cm2)

Moderate AS (AVA 1.0–1.5 cm2)

Severe AS (AVA <1.0 cm2)

Complementary Calculators

The Evidence

Validation

ESC/EACTS Guidelines for the management of valvular heart disease.

2014 AHA/ACC Guideline for the Management of Patients With Valvular Heart Disease.

Recent Journal Updates

AVA (Continuity Equation)

When to Use

When to Use

Key Points

How it Works

Formula

Severity Classification (Aortic Stenosis)

Clinical Pearls

Technical Considerations

Clinical Pearls

Next Steps

Mild AS (AVA >1.5 cm2)

Moderate AS (AVA 1.0–1.5 cm2)

Severe AS (AVA <1.0 cm2)

Complementary Calculators

The Evidence

Validation

ESC/EACTS Guidelines for the management of valvular heart disease.

2014 AHA/ACC Guideline for the Management of Patients With Valvular Heart Disease.

When to Use

When to Use

Key Points

How it Works

Formula

Severity Classification (Aortic Stenosis)

Clinical Pearls

Technical Considerations

Clinical Pearls

Next Steps

Mild AS (AVA >1.5 cm2)

Moderate AS (AVA 1.0–1.5 cm2)

Severe AS (AVA <1.0 cm2)

Complementary Calculators

The Evidence

Validation

ESC/EACTS Guidelines for the management of valvular heart disease.

2014 AHA/ACC Guideline for the Management of Patients With Valvular Heart Disease.

Recent Journal Updates