 Aortic Valve Velocity Ratio LV 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 Shortening PISA (Mitral regurgitation) dP/dt (LV contractility) LV Mass and LV Mass Index PISA (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 Equation Stroke Volume, Cardiac Output LV EF (Dumesnil Method) Myocardial Performance Index (LV)   Modified Bernoulli Equation      V1 m/s V2 m/s        ∆P mmHg         Simplified formula for converting velocity difference obtained by spectral Doppler to instantaneous pressure gradient.

This clinical equation has been derived from the more complex Bernoulli equation by assuming that viscous losses and acceleration effects are negligible and by using an approximation for the constant that relates to the mass density of blood, a conversion factor for measurement units.

In addition, the simplified Bernoulli equation assumes that the proximal velocity can be ignored, a reasonable assumption when velocity is <1 m/s because squaring a number <1 makes it even smaller. When the proximal velocity (V1) is over >1.5 m/s or the aortic velocity (V2) is <3.0 m/s, the proximal velocity should be included in the Bernoulli equation.

 ∆P = P2-P1 = 4(V22 – V12)

 Variable Definition V1 Proximal velocity (m/s) V2 Distal velocity (m/s) ΔP Instantaneous pressure gradient (mmHg) References Fatal error: Uncaught Error: Call to undefined function ereg_replace() in /u/c/cardio/www.csecho.ca/wp-content/themes/twentyeleven-csecho/cardiomath/index.php:472 Stack trace: #0 {main} thrown in /u/c/cardio/www.csecho.ca/wp-content/themes/twentyeleven-csecho/cardiomath/index.php on line 472