Echocardiography Flashcards
In Echo, how do wavelength and frequency affect resolution?
High frequency, shorter wavelength increase resolution
How does frequency affect tissue penetration?
Higher frequency decreases penetration
What is scattering and why does it happen?
Reflection of US beam in multiple directions due to structures less than 1 wavelength in lateral dimension
What is attenuation?
Absorption of US energy by conversion to heat
Depth of penetration is limited to what amount of wavelengths?
200 wavelengths
Depth of penetration for:
- 1 MHz transducer
- 2.5 MHz transducer
- 5 MHz transducer
- 30cm
- 12cm
- 6cm
Physics of M Mode
Single crystal rapidly alternating between transmission and receiver modes.
Safety of ultrasound?
No known adverse effects
However theoretical thermal damage and cavitation (creation of small gas filled bodies by the US beam)
What is image quality of 2D echocardiography affected by?
Axial resolution, lateral resolution and elevational resolution
Define axial resolution
Resolution along the length of the US beam
What affects axial resolution?
Frequency
Bandwidth
Pulse Length
Define lateral resolution?
resolution perpendicular to the beam
What affects lateral resolution?
Frequency Beam Width Bandwidth Aperture Side Lobes
Define elevational resolution?
Resolution across the thickness of the tomographic slice
What is the Nyquist Frequency?
Half the Pulse repetition frequency
What happens when velocity exceeds the Nyquist Limit?
Aliasing
What are the factors that affect colour doppler?
Gains
Colour Maps
Frame Rate
Nyquist Limit
What is use of pulse wave doppler
to assess low velocity flows
what is the use of continuous wave Doppler
to assess high velocity flows
What walls of the LV does the A4C view?
Anterolateral and inferoseptal
What walls of the LV does the A2C view?
Anterior and Inferior
What walls of the LV does the A3C view?
Anteroseptal and Inferolateral
What are the echo features of primary TR?
Flail gap 15mm or more
What are the echo features of functional or secondary TR?
Tenting Area >3cm
What is the normal aortic valve area?
3-4cm2
What is the peak velocity across the aortic valve which suggests severe stenosis?
> 4m/sec
What is the peak velocity across the aortic valve which suggests mild stenosis?
<3m/sec
What indexed aortic valve area represents severe stenosis?
<0.6cm2/m2
What are the echo features of mild aortic stenosis?
Valve area >1.5cm2
Transvalvular Velociy 2.0-2.9
Mean Gradient <20mmhg
What are the echo features of moderate aortic stenosis?
Valve area 1.0 - 1.5cm2
Transvalvular Velociy 3.0-3.9
Mean Gradient 20-39mmhg
What are the echo features of severe aortic stenosis?
Valve area <1.0cm2
Transvalvular Velociy >4
Mean Gradient 40mmhg
What are the features of severe aortic regurgitation on echocardiography?
Four of the following
- Vena contracta >6mm
- Flail Valve
- Central Jet Width >65% of LVOT
- Holodiastolic flow reversal in descending aorta
- Large flow convergence
- Enlarged LV with normal ED
- Pressure half time <200ms
OR 2-3 criteria with one or more of the following:
- Regurg fraction >50%
- Regurg Volume 60ml
- EROA >30mm2
What are the four echocardiographic measurements to assess LV systolic function?
Longitudinal shortening
Anterior mitral leaflet motion
Thickening of wall segments
Change in cavity area
Velocity of blood formula?
Velocity = wavelength * frequency
Wavelength formula?
Wavelength = 1.54 * frequency (MHz)
What is the general resolution of echo images?
1-2 wavelengths
What is the formula for acoustic impedance?
Acoustic impedance = density of the object * propagation velocity
What is the size that induces scattering?
Less than 1 wavelength
What are the physics characteristics of a sound wave?
Frequency Period Wavelength Propagation Speed Amplitude Intensity
What are the qualitative measures to assess valve regurgitation?
Valve morphology
Colour flow regurgitant jet
CW signal of regurgitant jet
Other - AR holodiastolic flow reversal, MR large flow convergence zone
What are the semi quantitative measures to assess regurgitant murmurs?
Vena contracta width
Upstream vein flow
Inflow
Other - AR pressure half time, TR Pisa radius, MR TVI mitral/TVI aortic
What are the quantitative measures to assess regurgitant valvulopathy?
Effective regurgitant orifice area
Regurgitant volume
Cardiac chamber and vessel enlargement
What are the qualitative echocardiogram features of severe AR?
Valve morphology - flail, coapt defect
Colour flow regurgitant jet - large central jet
CW signal of regurgitant jet - dense
Other - AR holodiastolic flow reversal in descending aorta >20cm/s
What are the qualitative features of severe MR and TR?
Valve morphology - coapt defect, flail leaflet, papillary muscle rupture
Colour flow regurgitant jet - large central or adhering eccentric jet reaching posterior LA wall
CW signal of regurgitant jet - dense, triangular
Other - large flow convergence zone (MR)
What are the semi quantitative measures that support severe AR?
Vena contracta width - >6mm
Pressure half time <200ms
What are the semi quantitative measures that support severe MR?
Vena contracta width - 7mm or more
Systolic pulmonary vein flow reversal
E wave dominant >1.5m/s
TVI mitral/aortic >1.4
What are the semi quantitative measures that support severe TR on echo?
Vena contracta width 7mm or more
Hepatic vein systolic flow reversal
Inflow E wave dominant >1
PISA radius >9mm
What are the quantitative measures that support severe AR on echo?
Effective regurgitant orifice area - >30mm2
Regurgitant volume - >60ml
LV enlargement
What are the quantitative measures that support severe TR on echo?
Effective regurgitant orifice area - >40mm2
Regurgitant volume - >45ml
RV RA IVC enlargement
What are the quantitative measures that support severe primary MR on echo?
Effective regurgitant orifice area >40
Regurgitant volume >60
LV LA enlargement
What are the quantitative measures that support severe secondary MR on echo?
Effective regurgitant orifice area - >20mm2
Regurgitant volume >30ml
What is the placement of the cursor for M mode assessment of LV Size and EF?
Plax
Base of heart
Perpendicular
(Up one intercostal space if not perpendicular)
What is the ERO associated with severe AR?
> 0.3
What is the regurgitant volume associated with severe AR?
> 60mls
Formula for mitral valve area with pressure half time.
Valve area = 220/pressure half time
Valve area = 760/deceleration time
Surface area of sphere
Surface area of half sphere (Pisa method)
4 Pi r squared
2 Pi r squared
What is the formula using Pisa to estimate mitral valve area in Ms?
MVA = 2 Pi r squared * Vr/Vmax * angle/180
Stroke volume equation
SV = 0.785 * D squared * VTI
MVA by the continuity equation.
MVA = (0.785 * D LVOT squared * LVOT VTI) / MV VTI
Regurgitation volume formula
RV = EROA * MR VTI
EROA formula from PISA
6.28 * r squared * nyquist limit / peak MR velocity
How does the eccentricity index assist in determining RV pressure vs volume overload?
Eccentricity index >1 only in end diastole indicates volume overload only
Index >1 in end systole and end diastole indicates pressure overload
What is normal RA volume in men and women?
34ml/m2 men
28ml/m2 women
What is the use of RV TDI S wave peak velocity in Pulmonary hypertension?
Prognostic value
What is the normal S wave value with TDI of the RV?
<11.5cm/s
What is the normal duration of the RV IVRT?
<110ms
Effective orifice area formula from SV and Transvalvular VTI
EO = SV/ transvalvular VTI
Formula for axial resolution?
Axial resolution = spatial pulse length / 2
Spatial pulse length formula?
SPL = wavelength * number of cycles
How does the potential trigger for takotsubo (physical vs emotional) influence outcome?
Physical trigger is associated with higher mortality
In retrospective data, what interventions are associated with improved outcomes for takotsubo cardiomyopathy?
ACE/ARB
Antiplatelets
No effect from b blocker on retrospective reviews
