Ch 3 M-mode Flashcards
What was the main mode of imaging before 2D/B-mode imaging?
M-mode
Why do we use m-mode?
To assess the rapid motion of cardiac structures
(valves, endocarditis chewing on valves, LV/RV wall motion)
Does m-mode have high or low frame rate?
High (1800 frames per second)
How many scan lines are produced with m-mode?
Single scan line produced repeatedly, in same direction
T/F: M-mode image generated shows non moving structures stationary while moving structures change location
True (think of how the valves look different on the image)
What does the x-axis + y-axis represent?
X: time
Y: depth
The first reflector the scan line hits is the most anterior or posterior structure in the m-mode tracing?
Anterior - each subsequent structure follows afterwards
(ex. RV, IVS, LV, LVPW, pericardium)
What does sweep speed change?
Number of cardiac cycles shown on horizontal axis
(lower speed = many wave forms in 1 image, higher speed = less wave forms)
When would we use a higher sweep speed?
When pt has high heart rate, so we can visualize event timing easier
(Fast HR = higher sweep speed)
When would we use a lower sweep speed?
When pt has slow heart rate
What is the standard sweep speed set at?
50 mm/s
At what angle should the cursor be placed to the structure of interest?
At 90 degrees (must be perpendicular)
What happens if our image is off axis + we do an m-mode?
Cursor will not be perpendicular to structure of interest, therefore measurements + tracings are considered inaccurate :(
What is the downside to using m-mode?
Image often off axis + done obliquely, creating an inaccurate tracing
What does GAIN enhance?
Brightness of returning signals
Can we adjust the GAINS on the overall image + on m-mode?
Yes
What does adjusting our depth do?
Allows for clearer visualization of the structure of interest
Should we optimize our 2D image before activating m-mode?
Yes!
What is anatomical m-mode (AMM)?
When the m-mode cursor can be rotated (opposed to in a fixed origin at the top of the 2D image like in regular m-mode)
Another name for anatomical m-mode?
Steerable m-mode
Why does anatomical m-mode create more accurate measurements?
-B/c we can make our cursor perpendicular to the structure if we can not make the structure of interest flat
-Good to use with pt’s in steep or off axis views
How do we obtain an m-mode of the AO/LA?
-Perform in PLAX (m/c) or PSAX AV level
-Place cursor over AV, at mid to tip leaflet
-Use ECG to determine timing of cardiac cycle to know where to measure
What happens during ventricular systole on an m-mode of the AO/LA?
-AV open (box shape)
-LA fills during atrial diastole (pushes AO wall anteriorly)
What happens during ventricular diastole on an m-mode of the AO/LA?
-AV closed (no box, thin echogenic line)
-LA contracts during atrial systole (AO wall moves posteriorly)
Are caliper measurements still performed on AO/LA m-modes in adults?
No
How do we obtain an m-mode of the MV?
-At PLAX (m/c) or PSAX MV level (center of fish mouth)
-Place cursor on tips of MV leaflets
Will the MV leaflets be open or closed during ventricular diastole?
Open
The AMVL has what appearance with m-mode?
M shape
The PMVL has what appearance with m-mode?
Blunted W shape
What does a “B bump” on MV m-mode represent?
Signals elevated LV end diastolic pressure (is normally a straight line, no bump)
What does EPSS stand for (during MV m-mode)?
E point septal separation
(distance b/w E point + posterior IVS, note the space here is normally only 2-7mm wide)
What does increased EPSS indicate in the absence of mitral stenosis?
-LV dilation
-Systolic dysfunction
-Aortic regurgitation
Are caliper measurements still performed on MV m-modes in adults?
No
How to obtain m-mode of LV?
-In PLAX (m/c) or PSAX PM view
-Place cursor perpendicular to PLAX, through center of LV just past the tips of the MV leaflets
Does the IVS + LV posterior wall move anteriorly or posteriorly during ventricular systole?
IVS: posteriorly
LVPW: anteriorly
(b/c squeezing together)
Does the IVS + LV posterior wall move anteriorly or posteriorly during ventricular diastole?
IVS: anteriorly
LVPW: posteriorly
(b/c relaxed)
Ejection fraction used to be calculated by the difference b/w what?
End diastolic diameter (EDD) + end systolic diameter (ESD)
Are caliper measurements performed still with LV m-mode in adults?
No
How do we measure leading edge to leading edge?
Outer to inner
(anterior of 1st visualized point to anterior of last visualized point)
What are all of the m-mode measurements we take in lab?
-AO diameter
-LA diameter
-EPSS (abnormal cases)
-IVSd
-LVIDd
-LVIDs
-LVPWd
(not routinely done in adult echos)
How do we measure the aortic root?
-At R wave (end diastole), before AV opens
-Outer to inner
How do we measure the LA?
-At end of T wave (end systole), or largest diameter of LA
-Outer to inner
What is the normal range of the EPSS at MV?
2-7mm
(remember distance b/w E point + posterior IVS)
Why do we only take wall measurements in diastole?
B/c we expect the walls to thicken in systole, they should not be thick in diastole which is why we measure then
List the measurements we take of the LV with m-mode to calculate the ejection fraction?
IVSd: outer edge of RV wall to LV side of the IVS in end diastole
LVIDd: LV side of IVS to inner edge of endocardium of LVPW in end diastole
LVPWd: outer edge of endocardium of LVPW to epicardial surface of LVPW in end diastole
LVIDs: LV side of IVS to inner edge of endocardium of LVPW in end systole
What is ejection fraction?
Amount of blood pumped from LV in each cardiac cycle
Do we have to measure our diastolic + systolic LV measurements on the same heart beat?
Yes!
Does peak systolic motion of the IVS occur slightly before or after peak systolic motion of the LV posterior wall?
Before
List 4 disadvantages of using m-mode?
-Beam orientation often off axis (leading to inaccurate measurements)
-Single line of sight
-Structure identification
-Technical variability (gains, sweep speed, cursor movement)
List 3 advantages to using m-mode?
-High frame rates (compared to 2D imaging)
-Provides precise measurements of cardiac dimensions (when cursor perpendicular to structure of interest)
-Evaluates structures further to complement 2D imaging
What can color m-mode assess?
Timing of regurgitation
What is “SAM”?
Systolic anterior motion of MV
(massive IVS hypertrophy seen on m-mode)
What pathology of the MV can m-mode assist in assessing?
MV stenosis
(small fish mouth)
How can m-mode assist in looking for a bicuspid AV?
Gauge eccentricity of the AV in the case of a bicuspid AV, seen during closure of valve
What is the reason that the American Society of Echocardiography primarily no longer recommends m-mode measurements for calculation of EF or chamber sizes?
Beam orientation frequently off axis
