Calculations Flashcards
Simplified Bernoulli.
△P = 4V*2
Long-form Bernoulli.
△P = 4 X (V22 - V12)
△Pmean can be estimated from △Pmax using the following equation.
△Pmean = (△Pmax/1.45) + 2mmHg
What does △Pmean approximate?
2.4V*2
EOA(AV)
EOA(AV) = (CSALVOT X VTILVOT)/VTIAV
Some versions of the continuity equation use the ratio of what in the LVOT/AOV instead of using VTIs?
Peak Velocities.
Zva (valvular-arterial impedance)
Zva = (PGmean + systolic BP)/SVi
MVA (continuity equation)
MVA = SVmv/VTImv
Stroke Volume
SV = CSA X VTI
CSA
CSA = 0.785 X d2 OR CSA = π X r2
MVA (pressure half-time equation)
MVA = 220/PHT
RVSP
RVSP = 4V*2 + RAP
Flow Rate
Flow Rate = Area X Velocity.
Regurgitant Volume (MR)
RV = SVmv - SVlvot
Regurgitant Fraction (MR)
RF = (RV/SVmv) X 100
PISA
PISA = 2πr*2
EROA (continuity equation)
EROA = (2πr*2 X Nyquist Limit)/Vmax(mr)
EROA (regurgitant volume) - MR
EROA = RV/VTImr
Regurgitant Volume (AR)
RV = SVlvot - SVmv
Regurgitant Fraction (AR)
RF = (RV/SVlvot) X 100
EROA (regurgitant volume) - AR
EROA = RV/VTIar
How can Tricuspid valve area be calculated from PHT?
TVA = 190/PHT
How is regurgitant flow rate calculated?
Regurgitant flow rate = PISA x Aliasing Velocity.
PASP (in the presence of pulmonary stenosis).
PASP = (4Vtr2 + RAP) - 4Vps2
How is the HV systolic filling fraction calculated?
HVSFF = S velocity/(S velocity + D velocity) X 100.
FAC (fractional area change) of the RV involves manual tracing of the RV endocardial border at end-diastole and end-systole. How has FAC calculated?
FAC = (RVAdiastole - RVAsystole)/RVAdiastole X100.
How can PA diastolic pressures be estimated?
4 X (PR end-diastolic velocity)*2 + RA pressure. Same as PASP but by using PR end-diastolic velocity rather than the TR velocity.
How is LV mass calculated?
LV mass = 0.8 {1.04 X [(LVIDd + LVPWd + IVSd)3 - (LVIDd)3]} + 0.6g
When calculating LV mass, which should particular care be taken when measuring 2D measurements?
As errors are amplified by cubing.
How is relative wall thickness calculated?
RWT = (2 X LVPWd) / LVIDd.