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Week 2: Aortic Regurgitation > Quantification of AR Severity > Flashcards

Quantification of AR Severity Flashcards

1
Q

Definition of Regurgitant Volume (RV)

A

Volume of blood through the leaky valve

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2
Q

Definition of Regurgitant Fraction (RF)

A
  • Regurgitant volume divided by total volume

- % of stroke volume through the leaky valve

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3
Q

Definition of Regurgitant Orifice Area (EROA)

A

Size of ‘hole’ in the leaky valve

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4
Q

Which calculations can be derived via stroke volume method?

A
  1. RV
  2. RF
  3. EROA
    (All can be derived via SV method)
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5
Q

Which calculations can be derived via PISA?

A
  1. RV

2. EROA

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6
Q

Concept for stroke volume through the LVOT in the presence of AR?

A
  • In diastole, regurgitant volume (RV) enters LV and combines with inflow stroke volume coming through MV
  • Therefore, SV LVOT = SV MV + RV
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7
Q

Stroke Volume Method: Formula to calculate AR Regurgitant Volume?

A

RV(AR) = SV LVOT - SV MV

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8
Q

Stroke Volume Method: Formula to calculate SV LVOT

A

SV LVOT = LVOT area x LVOT VTI

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9
Q

Stroke Volume Method: Formula to calculate mitral annular SV

A

SV MV = MV area x MV VTI

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10
Q

Stroke Volume Method: How to measure mitral annular diameter?

A
  • Zoomed view of A4V

- MV measured in early diastole (open valve leaflets) at leaflet insertion (inner edge to inner edge)

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11
Q

Stroke Volume Method: How to measure MV VTI?

A
  • Different to normal
  • Cursor placed at MV annulus level with 1-2mm sample volume
  • Trace modal velocity (dense part of signal) and avoid ‘fluffy’ bits
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12
Q

Normal mitral annulus diameter

A

3.0 - 3.5cm

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13
Q

Normal mitral annulus VTI

A

10 - 13cm

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14
Q

Normal LVOTd

A

1.8 - 2.2cm

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15
Q

Normal LVOT VTI

A

18 - 22cm

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16
Q

Stroke Volume Method: RVol formula for AR

A

RV (mL) = SV LVOT – SV MV

17
Q

Stroke Volume Method: RF formula

A

RF (%) = (RV / SV regurgitant valve) x 100

18
Q

Stroke Volume Method: EROA formula

A

EROA (cm2) = RV / VTI regurgitant valve

19
Q

Limitations of Stroke Volume Methods

A
  1. Diameter measurement errors
  2. VTI measurement errors
  3. Assumptions of calculation
  4. Significant learning curve in performing calculation - especially mitral annular stroke volume
20
Q

Assumptions of Stroke Volume Method Calculations

A
  1. Assumes flow occurs in a rigid, circular tube
  2. Assumes uniform velocity across vessel
  3. Assumes circular annulus areas
21
Q

PISA Method Principles/Assumptions

A
  • Assumes flow proximal to a narrowed orifice must flow through the narrowed orifice (continuity principle)
  • Assumes as flow converges towards narrowed orifice, it conforms concentric hemispheric shells
  • Assumes flow rate proximal to narrowed opening (Q1) = flow rate through narrowed opening (Q2)
22
Q

PISA Method: Equation for EROA

A

EROA= (2πr^2×VN)/VRJ

VN = Nyquist limit
VRJ = peak velocity of regurgitant jet (CW Doppler)
23
Q

PISA Technique

A
  1. Zoom in on AV
  2. Move colour baseline in direction of AR jet
  3. Cine to find optimal hemispheric PISA dome
  4. Measure PISA dome radius from regurgitant orifice to 1st aliased zone (red-blue interface)
24
Q

Which Nyquist limit to note when performing PISA calculation?

A
  1. If flow towards the Tx (red), note top of colour bar

2. If flow away from Tx (blue), note bottom of colour bar

25
Q

Which direction do you move colour baseline for PISA?

A
  • Always move baseline in the direction of flow
  • If flow is towards from the Tx, move baseline upwards (regurgitant flow is red)
  • If flow is away from the Tx, move baseline down (regurgitant flow is blue)
26
Q

Equation for Regurgitant Volume via PISA?

A

RV = EROA x VTI AR

27
Q

Is RV or EROA more useful in the assessment of AR?

A

RV because AR occurs in diastole and flow varies over the diastolic period

28
Q

Assumptions of PISA Method (Limitations)

A

Assumes that:

  1. Radius is consistent over flow period
  2. Regurgitant orifice is circular
  3. EROA is consistent over the flow period
29
Q

PISA Method Limitations

A
  • Multiple jets (not additive)
  • Aortic valve calcification
  • Under-estimation possible with aortic root aneurysms
30
Q

SV vs PISA Method: Which is preferred and why?

A
  • PISA method is preferred as there are less measurements

- The less measurements we have to do, the more reliable the method will be

Week 2: Aortic Regurgitation (3 decks)

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