Module 6 : PLAX Color and Spectral Doppler Flashcards
why do you we take the specific order of pictures (2D, Color, Spectral)
- 2D = images the structures
- Color = tells if leaking or stenotic (qualitative)
- Spectral = both quantifies normal and abnormal flows in the hear (quantitative)
Use of doppler in PLAX
- 2D as normal
- Zoom + Color
+ MV , AV
use of doppler in RVIT
- 2D as usual
- Color TV
- CW through the TV
why do we zoom on the Mitral valve
- easier to see ruptured chordae
- mitral valve prolapse
- need to see color from annulus to pap muscle
- and leakage/regurge
RVIT doppler
- make color box only as wide as the annulus
- assess for regurge
tricuspid valve spectral with CW
- measure the peak velocity of the spectral CW trace on the TV
- since velocity is directly proportional to the pressure the modified Bernoulli equation applies
modified Bernoulli equation
used to find the pressure gradient
pressure gradient = 4 (V^2)
pressure gradient
- difference between an atria and its corresponding ventricle
- use peak velocity
- only can be assessed with CW because PW will alias
Right Ventricle Systolic Pressure (RVSP)
- MUST ADD THE RIGHT ATRIAL PRESSURE
RVSP = 4(V^2) + RAP
RVSP = SPAP (systolic pulmonary artery pressure) in absence of RV obstruction to outflow
What 2 things do we need to calculate the RVSP
- the peak TR velocity
- IVC cine sniff test
Right Atrial Pressure RAP
- assessed by performing a sniff test in subcostal 4 chamber view
- we assume the IVC has the same pressure as the right atrium chamber
what is the normal response of IVC with sniff test
- IVC should collapse >50%
if RA pressure increases how is the IVC affected
- it could be dilated
- non collapsing
Calculating the RAP
- assess the IVC diameter is normal or abnormal
- assess if IVC collapsing is normal or abnormal
- use the corresponding value as your RAP
NORMAL IVC DIAMETER
= 21mm
ABNORMAL IVC DIAMETER
> 21mm
NORMAL IVC COLLAPSIBILITY
> 50%
ABNORML IVC COLLAPSIBILITY
< 50%
RAP for normal IVC diameter and collapsibility
3
RAP for normal IVC diameter but abnormal collapsibility
8
RAP for abnormal IVC diameter but normal collapsibility
8
RAP for abnormal IVC diameter and collapsibility
15
2D RVOT PLAX or PSAX
- optimise 2D
- show the pulmonary valve as clearly as possible
- show bifurcation if possible
RVOT color doppler
- color box only as wide as annulus
- optimize 2D first
- show pulmonary regurge if there
- can also be done in PSAX
- small amount of regurge is normal
+ looks like candle flame
RVOT/PA spectral doppler
- need to show pulmonary regurge AND RVOT/PA outflow
- usually pulsed wave works unless speeds are too high
PAT (pulmonary acceleration time)
- aka RVOT - AT
- measure with PW sample volume placed in RVOT
- how fast from opening of valves to fastest velocity
INCREASED PULMONARY PRESSURE DECRESASES PAT
NORMAL MPAP MEASUREMENTS
9 - 18 mmHg
OVER 20 IS REALLY BAD
wall filter/low velocity reject
- spectral signal should come close to the baseline
- too high of wall filter will block out those echoes losing information
