Hemodynamics Flashcards

1
Q

At what angle of flow is doppler shift not reliable?

A

20 deg (based on cos theta), cos 0 = 1

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2
Q

What is the area of a circle

A

0.785 x D2

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3
Q

How do calculate flow volume?

A

Area x VTI

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4
Q

How do you calculate stroke volume

A

(LVOT Diameter 2) x (0.785) x (LVOT VTI)

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5
Q

How do you calculate cardiac output

A

HR x Stroke volume

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6
Q

What is normal cardiac output

A

4-7 L/min

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7
Q

What is the Bernoulli equation?

A

4V 2

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8
Q

What are the pitfalls of the Bernoulli equation?

A

1) large angle theta
2) long tubular stenoses like aortic coarctation
3) Changes in blood velocity–polycythemia, anemia

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9
Q

How do you calculate RV systolic pressure?

A

1) Get peak TR signal by CW
2) TR velocity = difference between RV and RA
3) RVSP = 4(TR vel)2 + RAP

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10
Q

What is normal RVSP?

A

18-25 mmhg

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11
Q

What mean gradient is consistent with severe AS?

A

Greater than 40 mm hg

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12
Q

Can the peak gradient be measured by echo? Why?

A

No because aortic and LV peak gradients don’t occur at the same time

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13
Q

What is the continuity equation?

A

A1 x V1 = A2 x V2

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14
Q

Besides VTI, what else can be used in the continuity equation in addition to area? (A1 x ___ = A1 x ____)

A

Peak velocities

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15
Q

What is the dimensionless index?

A

VTI LVOT divided by VTI aortic valve
or
Velocity LVOT divided by Velocity aortic valve

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16
Q

What dimensionless index is associated with severe AS?

A

Less than 0.25

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17
Q

What AV area is normal?

A

3.0-4.0

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18
Q

What AV area is mild? Mean gradient?

A

1.5 cm2
<25 mm hg

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19
Q

What AV area is moderate? Mean gradient?

A

1.0-1.5 cm2
25-40 mm hg

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20
Q

What AV area is severe? Mean gradient?

A

<1.0 cm2
>40 mm hg

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21
Q

What does the pressure half time reflect?

A

The time for the LA to LV gradient to fall to half its peak value

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22
Q

Which mode is used to derive pressure half time?

A

CW doppler

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23
Q

What is the equation used to find MV area using pressure half time?

A

MVA = 220/PHT

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24
Q

How do you calculate pressure half time?

A

Vmax / 1.4 –> then find the time required to reach that velocity

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25
Q

In which circumstances can you NOT use the continuity equation to calculate MV area?

A

If significant aortic or mitral regurgitation present

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26
Q

What does the MV mean gradient reflect?

A

Average difference between LV and LA pressure

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27
Q

What type of doppler is used to find MV gradients?

A

CW

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28
Q

What elements affect MV mean gradients?

A

HR and CO

29
Q

What MV gradient is consistent with severe MS?

A

>10 mm hg

30
Q

What is a normal MV area?

A

4.0-6.0 cm2

31
Q

What MV area is mild? Mean gradient?

A

>1.5 cm2
<5 mm hg

32
Q

What MV area is moderate? Mean gradient?

A

1.0-1.5 cm2
5-10 mm hg

33
Q

What MV area is severe? Mean gradient?

A

<1.0 cm2
>10 mm hg

34
Q

How do you calculate Regurgitant volume of the MV?

A

Stroke volume MV - Stroke Volume LV

35
Q

How do you calculate Regurgitant volume of the AV?

A

Stroke volume LV - Stroke Volume MV

36
Q

What does effective regurgitant orifice measure in simple terms?

A

Lesion severity (size of the hole)

37
Q

What does regurgitant volume measure in simple terms?

A

Volume overload (how much blood goes through the hole)

38
Q

How do you calculate effective regurgitant orifice?

A

V MR max

39
Q

How do you calculate regurgitant volume using ERO?

A

ERO x VTI

40
Q

In a PISA equation, how do you calculate flow

A

(2πr2) x V Aliasing

41
Q

How do you calculate ERO?

A

V MR signal

42
Q

In which direction does the baseline get shifted when calculating PISA?

A

In same direction as regurgitant jet

43
Q

At what phase of the cardiac cycle is the radius measured in a PISA calculation?

A

mid-systole

44
Q

What can you assume for a MR Vmax for a simplified PISA?

A

500 cm/sec

45
Q

What ERO value correlates with mild MR? Regurgitant volume?

A

ERO <0.20 cm2
RV <30 cc

46
Q

What ERO value correlates with moderate MR? Regurgitant volume?

A

ERO 0.20-0.39 cm2
RV 30-59 cc

47
Q

What ERO value correlates with severe MR? Regurgitant volume?

A

ERO >0.40 cm2
RV >60 cc

48
Q

What ERO value correlates with mild MR? Regurgitant volume?

A

ERO <0.10 cm2
RV <30 cc

49
Q

What ERO value correlates with moderate AR? Regurgitant volume?

A

ERO 0.10-0.29 cm2
RV 30-59 cc

50
Q

What ERO value correlates with severe AR? Regurgitant volume?

A

ERO >0.30 cm2
RV >60 cc

51
Q

TTE better than TEE for measuring peak aortic, tricuspid, and/or mitral valve gradients?

A

Aortic and tricuspid but not mitral

52
Q

Above what velocity does PW doppler not become useful?

A

Above 2.5 meter/sec

53
Q

Where does a mitral regurgitant signal occur relative to the QRS complex? Why?

A

With the onset of the QRS–because there is no period of isovolemic contraction since it occurs through an AV valve

54
Q

Where does an aortic stenosis signal occur relative to the QRS complex? Why?

A

There is a gap after the QRS due to isovolemic contraction

55
Q

What is a good way to differentiate triscuspid regurgitation from mitral regurgitation signals?

A

Respiratory variation

56
Q

How do you calculate LVOT flow rate?

A

LVOT area x LVOT flow velocity

57
Q

How do you calculate pressure half time?

A

0.29 x deceleration time

58
Q

How do you calculate flow through an orifice? What about volume?

A
flow = area x velocity
volume = area x VTI
59
Q

What is a normal VTI for LVOT?

A

20-25

60
Q

How do you calculate pulmonary vascular resistance (PVR)?

A

TR velocity
————————– x 10 + 0.16
RVOT VTI

61
Q

What is a normal e’ velocity?

A

>8

62
Q

Is mitral inflow preload dependent or independent when looking at diastolic dysfunction?

A

dependent

63
Q

Is mitral annulus velocity preload dependent or independent when looking at diastolic dysfunction?

A

independent

64
Q

If patient has signs of heart failure and e’ greater than 8, what is the most likely diagnosis?

A

constriction

65
Q

Will triscupid regurgitation increase or decrease with increased stroke volume?

A

Increase

66
Q

What are the echo findings consistent with sickle cell anemia?

A

1) Increased wall thickness
2) Pericardial effusion
3) Increased PA systolic pressures

67
Q

What is associated with pulsus alternans?

A

Severe cardiomyopathy (i.e. 10% EF)

68
Q

What is the most common cause of pulmonary hypertension?

A

Increased LV filling pressure

69
Q

What is the significance of an L wave?

A

1) Delayed relaxation
2) Increased filling pressure