Physical formulas

Most common formulas used in echocardiographic calculations

ParameterDescriptionFormula
SoundSpeed of soundV = f · λ
Sound velocity constant in soft tissue1540 = f · λ
Nearfield lengthL = r² / λ
Frequencyf = 1 / T
DopplerDoppler formulaΔF = 2·f0·v / c · cosα
Doppler shiftPRF = 2 · f doppler
Nyquist limitAliasing = PRF / 2
Qs/QpShunt calculationπr² · VTI lvot / πr² · VTI rvot
MVAPressure half timeMVA = 220/PHT
TVAPressure half timeTVA= 190/PHT
MPITei indexMPI = (IVCT + IVRT) / ET
PISAFlowrateπr² · Vn
EROEffective regurgitant orifice Flowrate / Vmax MR
Regurgitation VolumeERO · VTI MR
OutputStroke volumeπr² · VTI lvot
Cardiac outputSV · HF
AVAContinuity EquationAVA = πr² · VTI lvot / VTI AoV
PressureGemodified Bernoulli equationΔP = 4 (V2² - V1²)
Simplified Bernoulli equationΔP = 4 · V²
PA pressureSystolic4 x (TR Vmax)² + estimated RAP
Diastolic4 x (PR Ved)² + estimated RAP
Mean0.3 x systolic PAP + 0.6 x diastolic PAP
90 - (0.62 x AccT) when AccT < 120ms
4 x (PR Vmax)² + estimated RAP
TR PGmean + estimated RAP
LVLV Volume(IVS + LVIDd + PW)³
Blood volume(LVIDd)³
Myocardial volume(IVS + LVIDd + PW)³ - (LVIDd)³
LV mass(IVS + LVIDd + PW)³ - (LVIDd)³ · 1.05
LV mass (Devereaux)1.04 [(IVS + LVIDd + PW)³ - (LVIDd)³] - 13.6

 

 

 

Armstrong, W.F, Ryan, T, “Physics and Instrumentation” in ‘Feigenbaum’s Echocardiography’, 7th ed, Philadelphia, Lippincott Williams & Wilkins, p.09-p.38

Armstrong, W.F, Ryan, T, “Hemodynamics” in ‘Feigenbaum’s Echocardiography’, 7th ed, Philadelphia, Lippincott Williams & Wilkins, p.217-p.241.