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EVALUATION OF SYSTOLIC FUNCTION OF LEFT VENTRICLE BY ECHOCARDIOGRAPHY. DR SANDEEP.R SR CARDIO. Basic Principle. Systole The period of the cardiac cycle from the closure of the mitral valve to the closure of the aortic valve. EJECTION FRACTION.
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EVALUATION OF SYSTOLIC FUNCTION OF LEFT VENTRICLEBY ECHOCARDIOGRAPHY DR SANDEEP.R SR CARDIO
Basic Principle Systole The period of the cardiac cycle from the closure of the mitral valve to the closure of the aortic valve
EJECTION FRACTION • Ejection fraction-percentage of LV diastolic volume that is ejected with systole • EF=STROKE VOLUME/EDV=EDV-ESV/EDV
IDEAL METHOD FOR EF CALCULATION • Accurate • Quick • Reproducible • Simple • Relatively independent of LV geometry
M-Mode Quantification • Use Parasternal Short-Axis or Long-Axis views to measure LVEDD and LVESD • Measurement is taken perpendicular to the ventricle at the level of tip of mitral leaflet • Assumes that no significant regional wall motion abnormalities are present
TECHNICAL ASPECTS Recommendations for chamber quantification*Eur J Echocardiography (2006) 7,79 108
LV MEASUREMENT - TTE 1.PLAX 2.PSAX AT PAPILARY MUSCLE
LV MEASUREMENT -TTE • 3) 2D METHOD • Useful for assessing patients with CAD • LV internal dimensions (LVIDd and LVIDs & • wall thicknesses be measured at mitral chordae level • 2D minor-axis dimensions smaller than M-mode measurements Recommendations for chamber quantification*Eur J Echocardiography (2006) 7,79 108
LV MEASUREMENTS - TEE a) ME-LAX b)TG-LAX c) TG –SAX preferred view Recommendations for chamber quantification*Eur J Echocardiography (2006) 7,79 108
LV MEASUREMENTS Recommendations for chamber quantification*Eur J Echocardiography (2006) 7,79 108
LV MEASUREMENTS Recommendations for chamber quantification*Eur J Echocardiography (2006) 7,79 108
Global Myocardial Function • Fractional shortening (FS) • Assumes symmetric contraction • Ejection fraction (EF) EF=EDV-ESV/EDV
TEICHOLZ /CUBED FORMULA • LV Volume calculation is based on assumption that the LV is a prolate ellipse • Basic assumptions • LV dilates along the minor axis • LV internal diameter is equal to one of the minor axis of the ellipse D1 • Both minor axisof ellipse D1,D2 are equal LV VOLUME= 4/3 xPi x D1/2 x D1/2 x 2D1/2 = Pi/3 x D cube =1.047 x D cube = D cube This structure has two minor axis D1 & D2 and a major axis L V=4/3 Pi X D1/2 X D2/2 X L/2
MODIFIED TECHOLZ • As LV becomes more spherical as it dilates the relation between major and minor axis changes. • Therefore a regression formula was devised to correct for this change in shape • LVV=( 7.0/2.4+D) x Dcube
MODIFIED QUINONES METHOD • Measure LVIDd &LVIDs • Calculate radial EF • If significant RWMA average EF measurement from basal & mid LV levels • Add factor for longitudinal shortening
SIMPSON’S METHOD • In the presence of RWMA all the above methods will be less accurate, since inclusion of RWMA- causes volume overestimation • The apical biplane methods are more robust in this setting, using summation of a series of disks from apex to base (often called Simpson’s Rule). • The ASE (American Society of Echocardiography) recommends use of biplane apical views with a modified Simpson’s rule approach
Simpson’s Rule – the biplane method of disks LV-ED LV-ES • Volume left ventricle - manual tracings in systole and diastole - area divided into series of disks - volume of each disc(πr2x h ) summed = ventricular volume • Preferred method of choice LV-ED LV-ES A4C A2C
AREA - LENGTH METHOD Hemi-cylindrical Hemi-ellipsoid Model Assumes: Base of ventricle = cylinder Apex of ventricle = ellipsoid Volume is calculated using a long axis length L and cross-sectional area Am of an orthogonal short-axis view at the mid-papillary muscle. V = (Am) L/2 + 2/3 (Am) L/2 V = 5/6 AL (Bullet Formula) VOLUME=5 (Area )(length)/6
VISUAL EF • Echocardiographic assessment of global left ventricular systolic function is usually performed subjectively • Experienced echocardiographers - estimate EF by looking at the overall size and contractility as well as the inward movement and thickening of the various segments of the LV walls without actually taking measurements • Correlate fairly well with angiographic assessment of the EF • Limitations: • Irregular rhythm • Very large or very small LV • Extremes of heart rate
COMPARISION OF VARIOUS ECHO METHODS WITH CINE ANGIO & RADIONUCLIDE VENTRICULOGRAPHY ESV & EDV CORRELATION Modified simpson’s rule showed maximum correlation with cine angio & RVG EF CORRELATION
Evaluation of LV Mass This is done by tracing the epicardial to calculate the total ventricular volume and the endocardial border to calculate chamber volume. LV mass = 1.05 (total volume – chamber volume)
LV Total Area LV Cavitary Area Length
Evaluation of LV Mass Total volume= Total area x length Chamber volume = Chamber area x Length Myocardial volume = Total volume – Chamber volume LV mass = Myocardial volume x density LV mass = Myocardial volume x 1.05
LV Mass Quantification • 2D M-Mode method using parasternal short axis view or parasternal long axis view • Assumes that LV is ellipsoid (2:1 long/short axis ratio) • Measurements made at end diastole • ASE approved cube formula: • LV mass (g) = 1.04 [(LVID + PWT + IVST)3 - (LVID)3] X 0.8 + 0.6 LV mass index (g/m2) = LV mass / BSA • Small errors in M-Mode cause large errors in mass values. Can have off axis/tangential cuts due to motion.
LV MASS-TEE • TEE evaluation of LV mass highly accurate,but has minor systematic differences in LV PWT • LV mass derived from TEE wall-thickness measurements is higher by an average of6 g/m2 • .
LV MASS RELATIVE WALL thickness= 2XPW/LVIDd
EPSS LIMITATIONS-INACCURATE AR MS 3) IWMI Lew W et al , American journal of cardiology 41:836-845,1978 Ahmadpour,H et al , American heart journal 106:21-28,1983:
B- notch • Delayed closure of mitral leaflets between the A and C (leaflet coaptation) points, determining a "notch" known as B-bump (small arrows) • Indicates increased left ventricular end-diastolic pressure ( > 20mmhg) • LIMITATIONS • 1) Low sensitivity • 2)false positive with first degree AV block & LBBB-due to prolonged AC interval Ambrose J A et al Circulation60:510-519 1979
MITRAL ANNULAR PLANE EXCURSION • M-mode tracings in systole • The magnitude of systolic motion is proportional to the longitudinal shortening of the LV • Normal mitral annular systolic motion is > 8mm (average 12 +/- 2 on apical4 or apical 2 views) • If motion is < 8 mm, the EF is likely < 50% • If <8mm -98% sensitive & 82% specific for EF <50%
GRADUAL CLOSURE OF AORTIC VALVE Decreased LV forward flow causes gradual reduction in forward flow in late systole This results in rounded appearance of aortic valve closure in late systole
Doppler Stroke Volume Calculation CARDIAC OUTPUT= STROKE VOLUME X HEART RATE
Doppler Stroke Volume Calculation • Assumption used for measuring SV using Doppler are: • Accurate cross-sectional flow area measurement. • Laminar Flow. • 3. Parallel intercept angle between Doppler beam and • direction of blood flow. • 4. Velocity and diameter measurements are made at the • same anatomic site.
ECHO VIEW PHASE ECHO VIEW PW SAMPLE VOLUME POSN.
Problems in this technique • 1. Apical 3-chamber view can be tried if Apical 5-c is difficult to obtain of velocities. • 2. Underestimation of flow velocities- LVOT may not be aligned with the direction of the PWD • an apical 3-chamber view may sometimes offer better alignment. • 3.When the parasternal long axis view is not obtainable, a LVOT diameter of 2cms for males and 1.75cms for females can be assumed. • 4.Variations in VTI with respiration • Movement of entire cardiawith respiration –difficult to obtain uniform velocities with PWD at LVOT
Pitfalls in Echo Calculation of CO • Accurate measurement of CSA • Weakest link in the calculation • VTI very good for assessing change in cardiac output with therapy, by following changes in VTI, since CSA is largely invariant in an individual • Measures forward flow only • Regurgitant fraction not considered • May over-estimate systemic cardiac output • Echocardiographic window in mechanically ventilated patients may be poor