EchocardiographyExercise StressMiscEchocardiography
Aortic Valve Velocity RatioLV EF (Modified Quinones Equation)Myocardial Performance Index (RV)
AVA (Continuity Equation VTI)LV EF (Simplified Quinones Equation)PCWP by E/Ea (Nagueh Formula)
AVA (Continuity Equation VMax)LV Fractional ShorteningPISA (Mitral regurgitation)
dP/dt (LV contractility)LV Mass and LV Mass IndexPISA (Mitral stenosis)
dP/dt (RV contractility)Mitral valve area (PHT)Qp/Qs
Left atrial pressure (MR)Mitral Valvuloplasty Score (MGH)RVSP (TR)
LA Volume (Biplane Method)Modified Bernoulli EquationStroke Volume, Cardiac Output
LV EF (Dumesnil Method)Myocardial Performance Index (LV)
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Aortic Valve Velocity Ratio/Dimensionless Index

Calculation


V1 m/s
V2 m/s


VR
Calculate

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Information

Definition of Aortic Stenosis Severity

VR
Normal 1.0
Mild >0.5
Moderate 0.25-0.50
Severe <0.25

Aortic Valve Velocity Ratio/Dimensionless Index

One approach to reducing error related to left ventricular outflow tract (LVOT) diameter measurements is removing the cross section area (CSA) from the simplified continuity equation. It is a ratio of the subvalvular velocity obtained by pulsed-wave Doppler and the maximum velocity obtained by continuous-wave Doppler across the aortic valve. This dimensionless velocity ratio expresses the size of the valvular effective area as a proportion of the CSA of the LVOT. Substitution of the time-velocity integral can also be used as there was a high correlation between the ratio using time–velocity integral and the ratio using peak velocities. In the absence of valve stenosis, the velocity ratio approaches 1, with smaller numbers indicating more severe stenosis. Severe stenosis is present when the velocity ratio is 0.25 or less, corresponding to a valve area 25% of normal. To some extent, the velocity ratio is normalized for body size because it reflects the ratio of the actual valve area to the expected valve area in each patient, regardless of body size. However, this measurement ignores the variability in LVOT size beyond variation in body size.

VR =
V1
V2

Variable Definition
V1 Subvalvular (LVOT) velocity (m/s)
V2 Maximum velocity across the valve (m/s)
VR Velocity Ratio

References


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