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ECHO ASSESSMENT OF LV SYSTOLIC FUNCTION
Fuad Farooq
Assessment of ventricular systolic function, the essential part of all echocardiography examinations
2D echo allows visualization of the endocardium and it’s thickening, by which global and regional ventricular systolic functions are assessed
Quantitative assessment of global systolic function is usually based on changes in ventricular size and volume
Systolic Function Variables
Fractional shortening of LV Ejection fraction Stroke volume and cardiac index Systolic tissue velocity of the mitral
annulus and myocardium Tissue tracking Regional wall motion analysis
Fractional Shortening
Percentage change in LV dimensions with each LV contraction
Reflects global ventricular function
LVED - LV end-diastolic dimensionLVES - LV end-systolic dimension
Limitation
Assesses ventricular function only at the level being interrogated If regional dysfunction is present, which is not
in the interrogation plane, it may result in a misleading estimate of global ventricular function
Ejection Fraction
Expression of global LV function
Strong predictor of clinical outcome in almost all major cardiac conditions
Determined visually by eyeballing echocardiographic images of the LV
Considerable inter-observer variation but with experienced readers variation is less than 5%
Measured quantitatively by using volumetric measurements from M-mode, 2D and 3D echocardiograms
LVEDV - LVESV LVEDV
LVEF =
EF can also calculated from LV dimensions measured with M-mode
Measurement of LV dimensions from the mid ventricular level is used to calculate LVEF
LVEDD2 – LVESD2
LVEDD2
Add 15% for normal, 5% for hypokinetic apex, 0% for akinetic apex, -5% for dyskinetic apex, and -10% for apical aneurysm
LVEF = x 100
Stroke Volume
Not a true indicator of systolic function Determined by multiple factors Provides the amount of blood volume
ejected with each cardiac cycle
Stroke volume can be measured as the difference between the LV end-diastolic volume and LV end-systolic volume obtained by the Simpson method
The difference should be equal to SV across the LVOT if there is no valvular regurgitation
If there is MR, regurgitant volume needs to be subtracted to obtain stroke volume across the LVOT
Calculated as
SV = LVOT area x LVOT TVI(time velocity
integral)
Cardiac output is calculated as:
CO = SV x HR
Cardiac index is calculated as:
CO Body Surface Area (BSA) CI =
Systolic Velocity of Myocardial Tissue or Mitral Annulus
Tissue Doppler imaging records the velocity of myocardial tissue
The systolic component (S’) of the mitral annulus correlates well with the LVEF
Value of 8cm/s was selected as a cutoff point
Vinereanu et al. have reported (80% sensitivity, 89% specificity) for the same cutoff point of S’ measured at the medial mitral annulus and (80% sensitivity, 92% specificity) for S’ measured at the lateral mitral annulus
Estimation of global left ventricular function from the velocity of longitudinal shortening. Echocardiography 2002;19(3):177-185
Ventricular Mechanical Synchrony
Systolic contraction of the ventricles is performed optimally when regional contractions are coordinated
All walls should contract within 20 to 30 milliseconds of each other
Disrupted by conduction delay, atrial fibrillation, or a pacemaker
Assessed best with tissue Doppler imaging
Reliably provide timings of cardiac events or myocardial movement
TDI in systole
TDI in diasystole
Tissue colour Doppler in M-mode
Tissue Tracking
It is byproduct of tissue Doppler imaging
Basoapical views of each ventricular segment are displayed as seven color bands, with each color representing a particular distance the tissue moves during systole
Tissue tracking provides a rapid assessment of systolic motion
Mitral anulus displacement can be determined instantaneously with tissue tracking
Normal mitral annular systolic motion is >8mm (average 12 + 2 on apical 4 or apical 2 views)
A systolic mitral anulus displacement of less than 5 mm determined by tissue tracking correlates well with a severe decrease in the LVEF (<30%)
Regional Wall Motion Analysis
Normal ventricular contraction consists of simultaneous myocardial thickening and endocardial excursion toward the center of the ventricle
Regional contractility or wall motion of the LV is graded by dividing the LV into segments
In 2002, a 17-segment model was recommended by the American Society of Echocardiography
LV is divided into three levels - basal, mid or papillary and apical
Circulation, 2002;105: 539-542
Basal1.Anteroseptum2. Anterior3. Lateral 4. Inferolateral 5. Inferior6. Inferoseptum
Segments
Mid1.Anteroseptum2. Anterior3. Lateral 4. Inferolateral 5. Inferior6. Inferoseptum
Apical1. Anterior2. Lateral 3. Inferior4. Septal
Apical cap
Numerical score is assigned to each wall segment on the basis of its contractility as assessed visually:
1= Normal (>40% thickening with systole)2= Hypokinesis (10-30% thickening)3= Severe hypokinesis to akinesis (<10% thickening)4= Dyskinesis (out of phase)5= Aneurysm (thinned and bulging outwards)
On the basis of this wall motion analysis scheme, a wall motion score index (WMSI) is calculated to semiquantitate the extent of regional wall motion abnormalities
Normal WMSI is 1WMSI > 1.7 may suggest perfusion defect >
20%
Qualitative estimation errors due to: Underestimation of EF due to endocardial
echo dropout and seeing mostly epicardial motion
Underestimation of EF with enlarged LV cavity; a large LV can eject more blood with less endocardial motion
Overestimation of EF with a small LV cavity Significant segmental wall motion
abnormalities
Normal
Abnormal
The Tei index
Myocardial performance index
TEI index = IVRT + IVCT LVET
IVCT - Isovolumic contraction time IVRT - Isovolumic relaxation time LVET - LV ejection time
Normal in 0.39 +/- 0.05
Indirect Markers
1. E-point septal separation2. Aortic valve opening pattern
E-point Septal Separation
The magnitude of opening of the mitral valve, as reflected by E-wave height, correlates with transmitral flow and, in the absence of significant mitral regurgitation, with left ventricular stroke volume
Mitral valve E point (maximal early opening) is within 6 mm of the left side of the ventricular septum
In the presence of a decreased ejection fraction, this distance is increased
Severe systolic dysfunction
Aortic Valve Opening Pattern
If left ventricular forward stroke volume is decreased, there may be a gradual reduction in forward flow in late systole, which results in gradual closing of the aortic valve in late systole. This results in a rounded appearance of the aortic valve in late systole