Method
AVA — Continuity Equation
⚠️ LVOT diameter measured in PLAX, midsystole. LVOT VTI and AV VTI measured from apical 5-chamber or 3-chamber. Ensure parallel alignment.
PLAX, midsystole, inner edge-to-inner edge
cm
PWD at LVOT, just proximal to valve
cm
CWD through aortic valve — maximum envelope
cm
m²
LVOT CSA = π × (LVOT d/2)²
LVOT SV = LVOT CSA × LVOT VTI
AVA (cm²) = LVOT SV / AV VTI
AVAi = AVA / BSA
SVi = SV / BSA
DI = LVOT VTI / AV VTI
LVOT SV = LVOT CSA × LVOT VTI
AVA (cm²) = LVOT SV / AV VTI
AVAi = AVA / BSA
SVi = SV / BSA
DI = LVOT VTI / AV VTI
Results
Continuity Equation
Enter values and click Calculate
Method
Projected AVA — Flow Normalization
📖 Projected AVA normalizes AVA to a standardized flow rate of 250 mL/s. Useful in low-flow states where true AVA may be underestimated. Based on Dumesnil/Pibarot methodology.
From continuity equation at current flow state
cm²
cm
cm
bpm
LVOT CSA = π × (d/2)²
SV = LVOT CSA × LVOT VTI
Flow rate = SV × HR / 60 (mL/s)
Proj. AVA = AVA × (250 / Flow rate)
Target flow: 250 mL/s (normal reference)
SV = LVOT CSA × LVOT VTI
Flow rate = SV × HR / 60 (mL/s)
Proj. AVA = AVA × (250 / Flow rate)
Target flow: 250 mL/s (normal reference)
Results
Projected AVA
Enter values and click Calculate
Method
Dimensionless Index (DI)
⚠️ DI is independent of LVOT diameter measurement and is useful when LVOT measurement is unreliable. DI < 0.25 = severe AS.
PWD at LVOT
cm
CWD through aortic valve
cm
m/s
m/s
DI (VTI) = LVOT VTI / AV VTI
DI (Vmax) = LVOT Vmax / AV Vmax
DI < 0.25 → Severe AS
DI 0.25–0.50 → Moderate AS
DI > 0.50 → Mild AS
DI (Vmax) = LVOT Vmax / AV Vmax
DI < 0.25 → Severe AS
DI 0.25–0.50 → Moderate AS
DI > 0.50 → Mild AS
Results
Dimensionless Index
Enter values and click Calculate
Low-Flow / Low-Gradient AS Classification
LFLG Classification & SVi
⚠️ Low-gradient AS (mean ΔP <40 mmHg with AVA ≤1.0 cm²) requires careful sub-classification. Each phenotype has different prognosis and management implications.
cm²
mmHg
m/s
%
cm
cm
m²
bpm
SVi = (LVOT CSA × LVOT VTI) / BSA
Flow state = SVi < 35 mL/m² → Low Flow
Classical LFLG: EF <50%, SVi <35, ΔP <40
Paradoxical LFLG: EF ≥50%, SVi <35, ΔP <40
Normal-flow LG: EF ≥50%, SVi ≥35, ΔP <40
True Severe HG: AVA ≤1.0, ΔP ≥40
Flow state = SVi < 35 mL/m² → Low Flow
Classical LFLG: EF <50%, SVi <35, ΔP <40
Paradoxical LFLG: EF ≥50%, SVi <35, ΔP <40
Normal-flow LG: EF ≥50%, SVi ≥35, ΔP <40
True Severe HG: AVA ≤1.0, ΔP ≥40
Results
LFLG Classification
Enter values and click Classify
LFLG Phenotypes
Classical LFLG
EF <50% + SVi <35 + ΔP <40. LV dysfunction reduces gradient — may be true severe AS. DSE indicated.
EF <50% + SVi <35 + ΔP <40. LV dysfunction reduces gradient — may be true severe AS. DSE indicated.
Paradoxical LFLG
EF ≥50% + SVi <35 + ΔP <40. Increased afterload + concentric remodeling. Higher mortality than expected. CT calcium scoring helpful.
EF ≥50% + SVi <35 + ΔP <40. Increased afterload + concentric remodeling. Higher mortality than expected. CT calcium scoring helpful.
Normal-Flow Low-Gradient
EF ≥50% + SVi ≥35 + ΔP <40. Often truly moderate AS or measurement error. AVA may be overestimated.
EF ≥50% + SVi ≥35 + ΔP <40. Often truly moderate AS or measurement error. AVA may be overestimated.
Dobutamine Stress Echo — AS Protocol
Low-Dose DSE (5–20 μg/kg/min)
⚠️ Indicated only in Classical LFLG-AS (EF <50%, AVA ≤1.0, ΔP <40). Target: HR increase 10–20 bpm or 20% increase in SV. Stop if SBP drops >20 mmHg, ischemia, or arrhythmia.
PLAX, midsystole, inner edge-to-inner edge
cm
Baseline (Rest)
PWD at LVOT
cm
CWD through aortic valve
cm
CWD — peak instantaneous gradient
mmHg
Peak Dobutamine (highest tolerated dose)
PWD at LVOT
cm
CWD through aortic valve
cm
CWD — peak instantaneous gradient
mmHg
AVA (rest/stress) = LVOT CSA × LVOT VTI / AV VTI
Contractile Reserve: ΔLVOT VTI ≥20%
True Severe: peak AVA ≤1.0 cm² AND peak ΔP ≥40 mmHg
Pseudo-severe: peak AVA >1.0 cm² at any flow
Indeterminate: AVA ≤1.0 but peak ΔP <40
Contractile Reserve: ΔLVOT VTI ≥20%
True Severe: peak AVA ≤1.0 cm² AND peak ΔP ≥40 mmHg
Pseudo-severe: peak AVA >1.0 cm² at any flow
Indeterminate: AVA ≤1.0 but peak ΔP <40
DSE Analysis
Pseudo-Severe vs. True Severe AS
Enter baseline and peak values, then click Analyze
Reference
AS Severity Cutoffs — AHA/ACC 2021 & ESC 2021
Grading integrates multiple parameters. No single value is definitive. Always assess in clinical context.
Mild
Vmax2.0–2.9 m/s
Mean ΔP< 20 mmHg
AVA> 1.5 cm²
AVAi> 0.85 cm²/m²
DI> 0.50
Moderate
Vmax3.0–3.9 m/s
Mean ΔP20–39 mmHg
AVA1.0–1.5 cm²
AVAi0.60–0.85 cm²/m²
DI0.25–0.50
Severe
Vmax≥ 4.0 m/s
Mean ΔP≥ 40 mmHg
AVA≤ 1.0 cm²
AVAi≤ 0.60 cm²/m²
DI< 0.25
Very Severe
Vmax≥ 5.0 m/s
Mean ΔP≥ 60 mmHg
AVA≤ 0.6 cm²
AVAi≤ 0.35 cm²/m²
Low-Gradient AS Phenotypes
Classical LFLG
EF< 50%
SVi< 35 mL/m²
Mean ΔP< 40 mmHg
AVA≤ 1.0 cm²
DSEIndicated
Paradoxical LFLG
EF≥ 50%
SVi< 35 mL/m²
Mean ΔP< 40 mmHg
AVA≤ 1.0 cm²
CT Ca scoreHelpful
Normal-Flow LG
EF≥ 50%
SVi≥ 35 mL/m²
Mean ΔP< 40 mmHg
ConsiderMod AS or error
DSE Criteria Summary
True Severe AS
Peak AVA≤ 1.0 cm²
Peak ΔP≥ 40 mmHg
Contractile reservePresent
→ AVR indicated
Pseudo-Severe AS
Peak AVA> 1.0 cm²
Peak ΔPAny
→ Moderate AS
→ Medical therapy
Indeterminate
Peak AVA≤ 1.0 cm²
Peak ΔP< 40 mmHg
No contractile reserve
→ CT Ca scoring
Aortic Valve Calcium Scoring (CT) — Supplemental
Severe AS (CT Ca)
Men≥ 2000 AU
Women≥ 1600 AU
⚠️ Clinical Disclaimer: This tool is intended as an educational and computational aid for trained echocardiographers and cardiologists. AS grading requires integration of multiple parameters and clinical context. Not a substitute for individual clinical judgment. Based on AHA/ACC 2021 and ESC 2021 valvular heart disease guidelines.