Module 2 : Ventricular Systolic Function Flashcards
LV function - systole
- ventricles pump blood into systemic and pulmonary circulation
- ensures adequate perfusion to the body
what is systolic dysfunction
- inability to contract
what 3 things does an inability to contract lead to
- decrease in SV/EF
- increased preload (LVEDP)
- ? congestive heart failure
LV function - diastole
- ventricular distention/ relaxation
- to be able to fill up to prepare for the next contraction
what is starlings law
- as filling occurs stretch in muscle develops tension/strength for contraction
what type of pressure gradient does diastole create
- negative pressure gradient to ensure venous return
what stage do the coronary arteries fill
- diastole
how is ventricular systole produced
- by depolarization of the ventricles followed by mechanical contraction
- ventricular myocardium contraction produces increased pressure within LV and RV
2 phases of systole
- isovolumic contraction
- ventricular ejection
what is isovolumic contraction
- all valves closed
- ventricular pressure is building up
what is ventricular ejection
- atrio-ventricular valves closed
- semilunar valves open caused by pressure gradient between LV and aorta
- ejection occurs until ventricular pressure equalizes with the great vessels
systole sequence
- myocardial depolarization»_space; contraction» ejection
- as pressure increases»_space; reduction of the internal volume of the chamber
timing of systole
- IVCT = onset of QRS
- ejection = starts when AV opens ends when AV closes
systolic, diastolic, mean pressure in AO
- sys = 120mmHh
- dia = 70mmHg
- mean = 85mmHg
systolic, diastolic, mean pressure in PA
- sys = 25mmHg
- dia = 10mmHg
- mean = 16mmHg
mean LA pressure
- 10mmHg
systolic and diastolic LV pressure
- sys = 120mmHg
- dia = 10mmHg
systolic and diastolic pressure RV
- sys = 25mmHg
- dia = 4 mmHg
mean RA pressure
- 4mmHg
5 steps of the ventricular pressure - volume relationship
- after depolarization of the ventricular muscle the LV/RV starts to contract
- contraction increases the intra-cavitary pressure
- pressure rises until it exceeds aortic/pa pressure which opens the AV/PV and blood is ejeceted
- after ejection LV/RV pressure falls below that of the aorta and pA which closes the AV PV
- pressure keeps falling during relaxation until MV and TV openm
what shape is the pressure loop for the LV and the RV and why
- LV = retangular
- RV = triangular
- lower right heart pressures
- lower impedance of the pulmonary vascular bed
three determinants of stroke volume
- preload
- afterload
- contractility
what is preload
- muscle length or stretch at end diastole
how do we estimate preload
- LVEDP = left ventricle end diastolic pressure
- PVEDP = pulmonary vein EDP
- LA pressure
what is after load
- the tension that the LV must overcome before fibre shortening and contraction
what three things affect after load
- changes in ventricular volume
- wall thickness
- vascular resistance
what is after load most often determined by
- SVR = systemic vascular resistance or blood pressure
is the RV or the LV more sensitive to after load
- RV
what is contractility
- aka inotropy
- inherent strength of the cardiac muscle and ability to shorten as contracts
what three factors increase stroke volume
- increase preload
- decrease afterload
- increase inotropy
quantitative systolic measurements
- fractional shortening FS
- ejection fraction EF
7 volumetric assessments of systolic measurement
- simpsons EF
- area length method
- stroke volume / CO / CI
- Dp/Dt
- tissue doppler
- MPI
- global strain
2 qualitative assessment of systolic function
- visual kinetic analysis (global EF estimation)
- segmental wall motion analysis
4 types of wall motion
- normal
- hypokinetic
- akinetic
- dyskinetic
teicholz ejection fraction
- LVIDd ^3 - LVIDs^3 / LVID^3 x 100
normal parasternal techolz EF
> /= 55%
fractional shortening equation
FS = LVIDd - LVIDs / LVIDd x 100
normal FS
> 25%
what does teicholz EF need to be accurate
- needs to have symmetrical contractility
what is fractional shortening
- % of change in the minor axis dimension
- has a correlation to EF
normal simpsons EF for male and female
male = 52-72 female = 54-74
3 signs of end diastole
- onset of QRS complex
- frame after MV closure
- frame where the LV diameter/dimension is largest
3 signs of end systole
- the frame proceeding MV opening
- when the LV is smallest
- near the end of the T wave
how to measure LVID with abnormal IVS
- when peak downward displacement of the septum is abnormal use the peak upward displacement of the posterior wall for timing
2 things needed for simpsons EF
- requires clear endocardial definition
- reduce depth to half way into th atria and sector down if possible
when would you never do Simpsons
- suboptimal endocardial definition
- IF YOU CANNOT SEE TWO ADJACENT SEGMENTS
how do we quantify left ventricle volumes
- end diastolic trace (A4C and A2C average)
- end systolic trace (A4C and A2C average)
stroke volume equation with EDV and ESV
SV = EDV - ESV
severe abnormal parasternal teichols EF
= 30
normal LV size women
= 5.3
severe abnormal LV size women
> /= 6.2
normal LV size men
= 5.9
severe abnormal LV size men
> /= 6,9
normal simpsons EF female
54-74
severe abnormal simpsons EF female
< 30
normal simpsons EF male
52-72
severe abnormal Ef male
< 30
4 tips/assumptions for SV calc
- accurate LVOT measurement
+ assumes LVOT is circular - Laminar flow assumed
+ plate sv in center of LVOT - parallel intercept angle between doppler beam and direction of flow
- velocity and diameter measurements are made at the same anatomic site
pressure over time equation
Dp/Dt
- Dp will ALWAYS equal 32mmHg
when is Dp/Dt measured
- the pre-ejection phase fo the cardiac cycle
- less influenced by loading conditions
what is Dp/Dt a measurement of
- rate of LV pressure rise during isovolumic contraction
what are the two arbitrary points chosen for Dp/Dt
1m/s and 3m/s
4 limitations of Dp/Dt
- valve click artifacts (prosthetic valves)
- eccentric MR jets (difficult to pick up CW)
- poor alignment to MR jets
- non compliant LA
how to do Dp/Dt
- optimize mitral regurge jet
- increase sweep speed to 100-200 cm/s
- draw a line from 1m/s to 3m/s
normal Dt
< 27 milisec
severe abnormal Dt
> 40ms
normal Dp/Dt values
> 1200 mmHg/s
severe abnormal Dp/Dt
< 800 mmHg/s
how are the muscle tissue in the LV arranged
- longitudinally
- radially
- circumferentially
what does tissue doppler measure
- speed that the LV muscle contracts in the longitudinal plane
- good measure of systolic function
what is normal LV s prime measurement
> 9.0cm/s
what is normal RV s prime measurement
> 9.5cm/s
6 s prime limitations
- can only truly reflect the performance of the basal segments in apical view
- if wall motion normal or globally down s prime will still be accurate
- if there are varying degrees of segmental systolic dysfunction s prime not as accurate
- s prime is influenced by tethering and translational motion of heart
- s prime velocity progressively decrease from base to apex
- TDI requires the optimal doppler angle
LIMP
- left index of myocardial performance
RIMP
- right index of myocardial performance
5 cases where index of myocardial performance is used
- dilated cardiomyopathy
- cardiac amyloidosis
- pulmonary hypertension
- RV infarction
- RV dysplasia
can MPI provide info on systolic and diastolic function
- yes
what is IMP a ration between
- isovolumic contraction time and isovolumic relaxation time divided by ejection time
normal LV LIMP doppler method
< 0.44
TDI MPI method LV normal LIMP
< 0.6
TDI MPI method RV normal RIMP
< 0.55
how is the RV size assessed
qualitatively
normal RV size - qualitative
- RV in A4C view should be less than 2/3 size of LV
- LV should dominate apex
Mild dilation of RV size - qualitative
- RV > 2/3 of LV but RV cavity is still smaller than LV
- RV apex more basal than LV apex as normal
moderate dilatation of RV - qualitative
- RV and LV share apex
severe dilatation of RV - qualitative
- RV > LV size
- RV occupies the apex
normal RV basal diameter
= 4.1 cm
normal mid cavity diameter RV
= 3.5cm
normal RV length
=8.6cm
RVOT diameter normal prox
= 3.3 cm
RVOT diameter normal distal
= 2.7cm
normal RV fractional area change
> /= 35%
normal MPI RV doppler method
= 0.43
TAPSE normal
> /= 12mm
5 methods to asses RV systolic function
- TASPSE
- RV s prime wave
- RV fractional area change
- RIMP
- RV stroke volume
what 3 things is RV stroke volume dependant on
- preload
- afterload
- contractility
qualitative LV systolic function assessment
- need to assess wall motion and thickening
- walls must be seen in 2 or more views to be scored