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DMST 283 ECHO 2 > Advanced Hemodynamics: Doppler Physics For Valvular Assessment > Flashcards

Advanced Hemodynamics: Doppler Physics For Valvular Assessment Flashcards

1
Q

What is the AVA formula?

A

((0.785 x D^2)(VTI))/VTI2

Or

(A1+V1)/V2

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2
Q

How do we calculate MVA?

A

Use a formula similar to AVA

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3
Q

What is a simple formula for AVA or MVA?

A

Stroke volume 1 = Stroke volume 2

Or

A1xV1 = A2xV2

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4
Q

What measurements do we need for formula for the MV?

A
  1. Measure LVOT
  2. LVOT PW trace (V1)
  3. Measure MV CW trace (V2),
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5
Q

What does PISA stand for?

A

Proximal isovelocity surface area

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6
Q

What is PISA radius?

A

When flow converges towards a small opening, it accelerates in a laminar manner forming a flow convergence zone

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7
Q

During PISA radius we have a series of concentric what?

A

Concentric hemispheric shells of the same velocity

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8
Q

In terms of PISA radias, as the flow gets closer to the hole what happens?

A

The diameter of each shell decreases as the velocity within each shell increases

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9
Q

In terms of PISA radius, a bigger shell equals what?

A

Bigger leak

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10
Q

When are we unable to use the LVOT as our control valve in the continuity equation?

A
  1. When we have aortic regurgitation
  2. When we have a long length of stenosis
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11
Q

How do we obtain PISA radius?

A
  1. Turn on colour
  2. Zoom MV
  3. Shift colour baseline between 20-40 cm/sec to produce aliasing
  4. Select PISA radius in MV mat package
  5. Measure radius from leaflet tips to top of aliased velocity
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12
Q

How do we find the PISA Radius: flow convergence zone?

A
  1. Use a A4C view with zoom and colour
  2. Baseline shifts down to 20-40 cm/s to enhance the hemispheric shells. (Baseline shift towards direction of flow)
  3. Measure vertical distance from leaflets to top of convergence zone (aliased interface)
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13
Q

Label the numbers

A
  1. Jet Height
  2. Flow convergence
  3. Vena Contracta
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14
Q

In terms of PISA, if we measure the peak regurgitation, we will be able to determine what?

A

The area of the regurgitation orifice

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15
Q

Because of PISA radius, we know that:
1. The aliasing velocity (the speed of the outside of the shell)
2. The radius of the shell
Which gives us what?

A

SV at the outside of the shell

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16
Q

To quantify MR with PISA, 4 variables are needed, what are they?

A
  1. PISA radius with colour doppler
  2. The aliasing velocity
  3. The peak velocity of the MR jet
  4. The velocity time integral VTI of the MR jet
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17
Q

Under pressure, due to the Bernoulli principle. Velocities are directly related to what?

A

The PG across the valve and so, we can use these PGs to estimate the pressures of the adjacent chamber

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18
Q

What is Bernoullis principle?

A

change in pressure = 4V^2

19
Q

When using the Bernoulli principle, A VTI trace not only gives us the max pressure gradient, but what?

A

The mean PG

20
Q

Under normal pressures which valve will have the highest velocity regurgitation jet?

A

The one with the most difference change in pressure.

This would be the one between the LA and the LV

21
Q

What changes might increase the velocity of a regurgitation jet?

A

An increase in pressure on one side of the valve.

22
Q

In terms of the Bernoulli’s principle, the mean PG tells us more of the story of what?

A

What is going on throughout the entire flow period

23
Q

In terms of Bernoulli’s principle each point on the trace has what?

A

4(V^2) applied to it, resulting in an average pressure gradient over the diastolic cycle = mean PG

24
Q

Why do we use MV inflow mean pressure gradient?

A

This is done because the waveform is not parabolic with a single peak like the AV and PV

25
Q

In terms of the MV inflow mean gradient, the PG varies how ?

A

Throughout the diastolic cycle, this results in the diastole is longer than the systole

26
Q

When assessing he AV we use what instead of peak velocity?

A

VTI

27
Q

What do we use to trace the doppler envelope to obtain mean gradient?

A

CW doppler

28
Q

How do we measure Mean TV pressure gradient?

A

Measured from the most parallel to TV flow

29
Q

Measuring the TV VTI works the same way as the MV with one caveat, what is it?

A

Average VTI over several beats to account for changes in Venous return with respiration

30
Q

Pressure half time is a measurement of what?

A

Of the time it takes for the early diastolic pressure gradient to half of its original value

31
Q

In terms of MV/TV stenosis. A normal MV PG does what?

A

Decreases quickly

32
Q

In terms of a MV/TV stenosis LA pressure is ______ LV pressure for only a short time during diastole, with the pressure quickly doing what?

A
  1. Greater
  2. Dropping down to less than LV again
33
Q

In terms of Pressure half time what is the general rule for MV inflow?

A

Normal MV inflow = quick P(1/2)t

34
Q

When the pressure in the LA is high due to MS, what happens to the LA pressure period? What does this mean in terms of pressure half time?

A

The LA pressure stays higher, longer. Therefore

Increased MS = increased P(1/2)t

Normal TV/MV wave = Short P(1/2)T

35
Q

MVA can be derived by dividing what?

A

Divine 220 (a constant) by P(1/2)T

36
Q

How do we calculate the TV pressure half time?

A

Same principle as MS

37
Q

What is the limitation of PHT for TV?

A

Tachycardia

38
Q

In terms of TV PHT, With TS, the PHT greatly does what?

A

Increase

39
Q

In terms of PHT we can use the same concept of what? We use this to do what?

A
  1. How quickly pressure fall to assess AR/PR
  2. Compare the LV pressure to the Ao pressure during diastole
40
Q

In terms of PHT, as AR severity increases what happens?

A
41
Q

In terms of PHT for PR we use the same concept as what?

A

AR

42
Q

What is the PR A-dip

A
  1. You may see the A dip in the PI waveform with normal PA pressure
  2. This happens just after the P wave
43
Q

How can we summarize PHT in terms what is good and what is bad?

A
44
Q

What is the formula for RVSP?

A

(4(TRvel)^2) +RAP

DMST 283 ECHO 2 (14 decks)

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