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