C2: Ventricular Systolic Function Flashcards
briefly describe/review IVCT, sysole, IVRT and distole
see notes from last semester
what are the systolic and diastolic pressures in the LV
S: 120 mmHg
D: 10 mmHg
what are the systolic and diastolic pressures in the RV
S: 25 mmHg
D: 4 mmHg
Mean LA pressure
10 mmgH
Mean RA pressure
4 mmHg
review ECG timing for IVCT, sysole, IVRT and distole and AP
see notes from last semester
w/ a compliant ventricle, can it accommodate an increase in volume w/o much change in pressure
yes
review pressure-volume loop in notes
what shaped pressure-volume loop does the LV have
rectangular
what shaped pressure-volume loop does the RV have
why is it different than the LV
triangular
lower pressures in the RH and lower impedance of the pulmonary vascular bed
does flow continue to enter the PA from the RV even after peak pressure is reached
yes
what 3 things determine stroke volume
preload
afterload
contractility/inotropy
Changing any one of these variables will effect the others
describe how preload effects stroke volume
changes in preload alter end-diastolic volume which will change the amount of starlings principle and effect SV
what are the 2 ways that we use to estimate preload
LVEDV
PVEDP or LA pressure
describe how afterload effects stroke volume
more resistance to the ventricle emptying will lead to less blood being ejected
in the RV or LV more sensitive to afterload
RV (because its less muscular so it will dilate rather than hypertrophy)
what are some quantitative systolic measurements
FS (N: >25%) EF (Simpsons: M: 52-72, W: 54-74, Teicholz: >/= 55%) SV Delta P/ Delta T TDI Strain
what are some qualitative systolic measurements
visual EF
segmental wall analysis (normal, hypo, akinetic, dysk.)
why is Teicholz less accurate than Simpsons
only looking at motion of 2 segments instead of 17
what is fractional shortening
% change in the minor axis dimension
2 methods for estimating LV volume
Simpsons
Area length
difference b/w simpsons and area length method
S: uses the average of the endocardial tracings in A4CH and A2CH
A: trace the LV chamber in PSAX @ the pap lvl and measure the LV length on A4CH from Mv annulus to apex
if you dont see 2 adjacent segments, should you do EF
no
the length of the ventricles in A2 and A4 in simpsons shouldnt differ by more than what value
0.5cm or 10%
when would you use the area/lengh method for LV volume
if endocardial definition is suboptimal from apical images but parasternal views are good
value for severely reduced Fractional Shortening for M and W
M: = 14 % W: = 16 %
value for severely reduced parasternal/teicholtz EF for M and W
Both: =30 %
value for severe dilation of LVIDd for M and W
M: >/= 69 mm
W: >/= 62 mm
preferred SV formula/method
SV = pie(r^2) x VTI
assumptions for SV calculation
- accurate LVOT measurement
- LVOT is circular
- laminar flow
- parallel insonation when doing PW of the LVOT to get the VTI
- PW and LVOT measurement were made at the same place
what does delta pressure/delta time (Dp/Dt) measure
measures how much time it takes for the LV pressure to rise by 32 mmHg if the LV were contracting for 1 full second….uses the MR jet
Dp will always be 32 mmHg (t in seconds) or 32000 (t in ms)
when is Dp/Dt measured
pre-ejection phase (IVCT)
is Dp/Dt more or less dependent on pre-load than SV, CO and CI
why
less, because its measured during the pre-ejection phase
Dp/Dt uses which principle
bernoulli
do severe MR and impaired LV systolic function often occur together
yes
how can the EF remain normal or above normal with MR
the changes in pre-load caused by the MR
whats the benefit of Dp/Dt being less effected by preload
makes it a good tool to assess the true systolic function of the LV
limitations of Dp/Dt that make the calculation less accurate
valve click artifact (w/ prosthetic valves)
may not pick up eccentric MR jets
poor alignment to MR jet
non-compliant LA
how to do Dp/Dt
- optimize MR jet in CW (early systole is most important)
- increase sweep speed to 100-200cm/s
- draw line from 1m/s-3m/s for delta T
norm value for delta t
how long should it take for the LV to generate 32 mmgH
<27 ms
what value is severely abnormal for delta t
> 40 ms
norm value for Dp/Dt
> 1200 (mmHg/s)
severely abnorm value for Dp/Dt
<800 (mmHg/s)
norm value for S prime velocity for LV
> 9 cm/s
TDI measures the speed of LV contraction in which plane
longitudinal
if E prime is depressed, how will that effect S prime
will also be depressed
limitations of S prime
- only reflects movement at base of the heart so wont be accurate if there are abnormal segments
- influenced by tethering and translational motion of the heart
- S prime velocities progressively decrease from base to apex in a norm heart
- need optimal doppler angle
what is tethering
when a hypo or akinetic segment is adjacent to a norm segment and gets pulled around by its motion
what is LIMP and RIMP
when are they used
indices of myocardial performance… a ratio b/w IVCT and IVRT/ejection time
dilated cardiomyopathy cardiac amyloidosis pulmonary hypertension RV infarction RV dysplasia
what info does IMP/MPI provide
info about systolic and diastolic function
formula for MPI
(IVCT + IVRT) / ET
2 methods for IMP/MPI
conventional doppler method (preferred)
TDI method
norm LIMP value w/ the doppler method
norm LIMP value w/ the TDI method
D: < 0.44
TDI: < 0.6
in a diseased heart, what happens to ejection time, IVRT and IVCT
ejection time decreases and the others increase
if LIMP and RIMP are elevated, what does that say about pressure in the heart
means its taking longer for press to rise and fall
what 2 doppler waveforms do you need to show in the same tracing for LIMP (doppler method)
what do you need to TDI method
LVOT outflow and MV inflow so that you can measure IVCT, IVRT and ET
TDI only tracing
norm value for RIMP w/ doppler method
norm value for RIMP w/ TDI method
D: = 0.43
TDI: = 0.54
why is the TDI method of calculating RIMP and LIMP not preferred
it only gives information about the walls sampled
in A4Ch, the RV should appear how much smaller than the LV
less than 2/3 the size of the LV
describe the appearance of mild dilation of the RV
Rv >2/3 of the LV but still smaller than LV
describe the appearance of moderate dilation of the RV
RV and LV share the apex and are equal size
describe the appearance of severe dilation of the RV
RV > LV size and occupies the apex
can the RV dilate due to MR
yes
norm values for RV basal, mid and length
B: = 41 mm M: = 35 mm L: = 86 mm
norm values for RVOT diameter prox and distal
prox: = 33 mm
dis: = 27 mm
norm value for TDI s prim RV
> /= 9.5 cm/s
norm value for FAC
> /= 35%
in order to qualitatively assess LV systolic function of individual segments, do you need to see each segment in 2 or more views
yes
