Calculations

Question 1

What is PISA

Answer 1

• Any surface area proximal to a narrowed orifice at which all blood velocities are equal
  o Area of flow convergence and acceleration
   As perfect hemisphere as possible

o The larger the blood volume that moves through = the larger the proximal hemisphere is
 Lack of flow convergence = consistent with small volume

Question 2

Assumptions PISA

Answer 2

 Flow accelerates as it approaches the small orifice
 Acceleration is in concentric hemispheres on ventricular side of the valve = series of hemispheric waves with same velocity at surface of each wave
* iα to ROA = ↑ velocity with ↓ ROA

Question 3

Equations PISA

Answer 3

Reg fraction = PISA x aliasing velocity

ROA = Reg FR/velocity of reg

Rvolume = ROA x VTI of reg

PISA = pir2

Rvol = regurgitant volume
Rfr = regurgitant flow rate
Vrj = velocity of regurgitant jet

Question 4

How to determine PISA on echo

Answer 4

o Apicar 4 chamber view
o Centrally directed MR
o See flow convergence, vena contracta, jet expansion
o Nyquist limit = 50-70cm/s
o Use largest MR jet during systole
o PISA identified by the red/blue aliasing interface

• Aliasing velocity: border of the PISA
  o Flow rate at PISA = flow rate across regurgitant orifice
   Regurgitant flow rate (regurgitant SV) = PISA x aliasing velocity
   EROA x MR velocity = 2r2 x aliasing velocity
   EROA = 2r2 x aliasing velocity/ MR velocity
   MR regurgitant volume = EROA x VTI

Question 5

PISA limitations

Answer 5

o Flattened PISA = underestimation of MR
o Oval shaped PISA = over estimation of MR
o Limited to low frame rates
o Less accurate with eccentric jets
o Gain dependent: color Doppler measure velocity, not flow

Question 6

Effective regurgitant orifice area (ROA) calc

Answer 6

• Calculated by multiplying regurgitant fraction to VTI of MR jet
  o <0.2 cm2 = mild insufficiency
  o 0.2-0.39 cm2 = moderate MR
  o >0.4 cm2 = severe MR

EROA = RF x VTIMR

Question 7

Methods to calculate regurgitant volume

Answer 7

PISA
Volumetric

Question 8

Methods to calculate regurgitant volume: PISA

Answer 8

o Regurgitant volume = EROA x regurgitant TVI
o Severe MR have 75% of LV volume move backward into LA
o Moderate MR have 45-75% of LV volume move backward into LA
o Mild MR have <45% of LV volume move backward into LA

Question 9

Methods to calculate regurgitant volume: volumetric method

Answer 9

o Total forward SV = systemic SV + regurgitant volume
o Regurgitant volume = subtract forward volume ejected through Ao (systemic volume) with total forward SV from LV
 Ao SV: can be determined by CSA of AoV and VTI of Ao flow
* Valve used for normal SV should not be insufficient
 MV SV: can be determined by CSA of MV and VTI of MV flow