Hemodynamics Flashcards
At what angle of flow is doppler shift not reliable?
20 deg (based on cos theta), cos 0 = 1
What is the area of a circle
0.785 x D2
How do calculate flow volume?
Area x VTI
How do you calculate stroke volume
(LVOT Diameter 2) x (0.785) x (LVOT VTI)
How do you calculate cardiac output
HR x Stroke volume
What is normal cardiac output
4-7 L/min
What is the Bernoulli equation?
4V 2
What are the pitfalls of the Bernoulli equation?
1) large angle theta
2) long tubular stenoses like aortic coarctation
3) Changes in blood velocity–polycythemia, anemia
How do you calculate RV systolic pressure?
1) Get peak TR signal by CW
2) TR velocity = difference between RV and RA
3) RVSP = 4(TR vel)2 + RAP
What is normal RVSP?
18-25 mmhg
What mean gradient is consistent with severe AS?
Greater than 40 mm hg
Can the peak gradient be measured by echo? Why?
No because aortic and LV peak gradients don’t occur at the same time
What is the continuity equation?
A1 x V1 = A2 x V2
Besides VTI, what else can be used in the continuity equation in addition to area? (A1 x ___ = A1 x ____)
Peak velocities
What is the dimensionless index?
VTI LVOT divided by VTI aortic valve
or
Velocity LVOT divided by Velocity aortic valve
What dimensionless index is associated with severe AS?
Less than 0.25
What AV area is normal?
3.0-4.0
What AV area is mild? Mean gradient?
1.5 cm2
<25 mm hg
What AV area is moderate? Mean gradient?
1.0-1.5 cm2
25-40 mm hg
What AV area is severe? Mean gradient?
<1.0 cm2
>40 mm hg
What does the pressure half time reflect?
The time for the LA to LV gradient to fall to half its peak value
Which mode is used to derive pressure half time?
CW doppler
What is the equation used to find MV area using pressure half time?
MVA = 220/PHT
How do you calculate pressure half time?
Vmax / 1.4 –> then find the time required to reach that velocity
In which circumstances can you NOT use the continuity equation to calculate MV area?
If significant aortic or mitral regurgitation present
What does the MV mean gradient reflect?
Average difference between LV and LA pressure
What type of doppler is used to find MV gradients?
CW
What elements affect MV mean gradients?
HR and CO
What MV gradient is consistent with severe MS?
>10 mm hg
What is a normal MV area?
4.0-6.0 cm2
What MV area is mild? Mean gradient?
>1.5 cm2
<5 mm hg
What MV area is moderate? Mean gradient?
1.0-1.5 cm2
5-10 mm hg
What MV area is severe? Mean gradient?
<1.0 cm2
>10 mm hg
How do you calculate Regurgitant volume of the MV?
Stroke volume MV - Stroke Volume LV
How do you calculate Regurgitant volume of the AV?
Stroke volume LV - Stroke Volume MV
What does effective regurgitant orifice measure in simple terms?
Lesion severity (size of the hole)
What does regurgitant volume measure in simple terms?
Volume overload (how much blood goes through the hole)
How do you calculate effective regurgitant orifice?
V MR max
How do you calculate regurgitant volume using ERO?
ERO x VTI
In a PISA equation, how do you calculate flow
(2πr2) x V Aliasing
How do you calculate ERO?
V MR signal
In which direction does the baseline get shifted when calculating PISA?
In same direction as regurgitant jet
At what phase of the cardiac cycle is the radius measured in a PISA calculation?
mid-systole
What can you assume for a MR Vmax for a simplified PISA?
500 cm/sec
What ERO value correlates with mild MR? Regurgitant volume?
ERO <0.20 cm2
RV <30 cc
What ERO value correlates with moderate MR? Regurgitant volume?
ERO 0.20-0.39 cm2
RV 30-59 cc
What ERO value correlates with severe MR? Regurgitant volume?
ERO >0.40 cm2
RV >60 cc
What ERO value correlates with mild MR? Regurgitant volume?
ERO <0.10 cm2
RV <30 cc
What ERO value correlates with moderate AR? Regurgitant volume?
ERO 0.10-0.29 cm2
RV 30-59 cc
What ERO value correlates with severe AR? Regurgitant volume?
ERO >0.30 cm2
RV >60 cc
TTE better than TEE for measuring peak aortic, tricuspid, and/or mitral valve gradients?
Aortic and tricuspid but not mitral
Above what velocity does PW doppler not become useful?
Above 2.5 meter/sec
Where does a mitral regurgitant signal occur relative to the QRS complex? Why?
With the onset of the QRS–because there is no period of isovolemic contraction since it occurs through an AV valve
Where does an aortic stenosis signal occur relative to the QRS complex? Why?
There is a gap after the QRS due to isovolemic contraction
What is a good way to differentiate triscuspid regurgitation from mitral regurgitation signals?
Respiratory variation
How do you calculate LVOT flow rate?
LVOT area x LVOT flow velocity
How do you calculate pressure half time?
0.29 x deceleration time
How do you calculate flow through an orifice? What about volume?
flow = area x velocity volume = area x VTI
What is a normal VTI for LVOT?
20-25
How do you calculate pulmonary vascular resistance (PVR)?
TR velocity
————————– x 10 + 0.16
RVOT VTI
What is a normal e’ velocity?
>8
Is mitral inflow preload dependent or independent when looking at diastolic dysfunction?
dependent
Is mitral annulus velocity preload dependent or independent when looking at diastolic dysfunction?
independent
If patient has signs of heart failure and e’ greater than 8, what is the most likely diagnosis?
constriction
Will triscupid regurgitation increase or decrease with increased stroke volume?
Increase
What are the echo findings consistent with sickle cell anemia?
1) Increased wall thickness
2) Pericardial effusion
3) Increased PA systolic pressures
What is associated with pulsus alternans?
Severe cardiomyopathy (i.e. 10% EF)
What is the most common cause of pulmonary hypertension?
Increased LV filling pressure
What is the significance of an L wave?
1) Delayed relaxation
2) Increased filling pressure
