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Assessment of LV Systolic Function
Dr Nithin P G
Overview • Normal LV contraction
• Hemodynamics & Angiographic assessments
• Echocardiography
• MRI
• Computed Tomography
• Nuclear Imaging
Introduction• Mechanical pump
• LV systolic function = Contractility
Normal contraction of LV
J Am Coll Cardiol Img 2008;1:366 –76
ASSESSMENT OF LV FUNCTION
Clinically relevant indicators of global LV function
EJECTION FRACTION. • Ratio of SV to EDV. [EDV-ESV/EDV]
– Simplicity of its derivation – Ability to determine easily – Reproducibly using different imaging techniques – Extensive documentation of its clinical usefulness.
Ejection fractionDrawbacks
– Depends on preload and afterload, as well as HR and synchronicity of contraction.
– Global parameter, major regional differences in contractility are presented as an average
– Given EF may have different prognostic importance according to clinical situation eg severe MR
Preload increases [AR,MR, Anemia]
EF increases
Afterload increases [AS] EF decreases
Hemodynamic measurements• Cardiac index (liter/min/m2) = HR × SV/BSA
• Stroke Volume index (ml/m2) = SV/BSA
• Stroke Work index (ml×mmHg/m2) = SVI × mean SBP
– LVSW reasonably good measure of LV contraction ,exceptions
• Volume or Pressure overload
• RWMA
ESPVRESPVR or maximum elastance- method for LV contractility• Nearly independent of preload and afterload• Multielectrode catheters –impedance, Vol., micromanometer Pressure
recordings [aortic dicrotic notch pressure as ESPr & Minimum LV chamber volume ]
• Pacing/ IVC balloon occlusion/ Drugs PV loops at different loads line drawn across ES points
• Slope of line = measure of LV contractility
ESPVR• ESPVR accurately reflect myocardial contractility independent of
ventricular loading [ in various canine and human studies]
• Drawbacks• Difficult to perform• Invasive • Spontaneous variability over the time it takes to make
measurements• Curves dependent on gender, age, position of IVS [RV filling
pressure, LBBB]
MAXIMAL RATE OF PRESSURE RISE• Maximum rate of rise of LV Sys. Pr. [IVC]• Analogous to the maximal rate of tension development of isolated
cardiac muscle [well-established index of myocardial contractility]• Relatively load independent [ changes to afterload & preload < 10%
in normal physiological limits]
Drawbacks• Comparison b/w individuals
difficult• c/c AS dP/dt less when
contractility normal• RWMA & marked dyssynchrony
Regional Indices of Left Ventricular Function
• WMS [wall motion score]
• Center line chordal shortening
• Radian change, regional area change
• Strain rate imaging
• Torsion imaging
Centerline method
ANGIOGRAPHIC ASSESSMENT
Volume calculationsV= 4/3 p [L/2] [M/2] [N/2] = p /6 LMN
ARAO= p [LRAO/2] [ M/2]= p [LRAO][M]/4ALAO= p [LLAO/2] [N/2]= p [LLAO][N]/4
V= p /6 Lmax [4ARAO] [4ALAO] [p LRAO][p LLAO]
Usu, Lmax= LRAO
=> V= 8 ARAO ALAO
3 p LLAO
Regional indicesAngiographic wall motion score
– 1= normal– 2= moderate hypokinesis– 3=severe hypokinesis– 4=akinesis– 5=aneurysm/dyskinesis
• Normal score is 5
ECHOCARDIOGRAPHY
Assesment by EchocardiographyEjection Fraction1. M- mode• EF= LVEDD2-LVESD2 x100 LVEDD2
• EFc= [(1-%EF) x % DL] + %EFDL=apex contractility
15% normal 5% hypokinetic 0% akinetic -5% dyskinetic -10% aneurysmal
– Only along a single interrogation line, regional variation in function– Does not reflect true minor axis especcially in elderly with angulation
Ejection fraction2. D3 method
D1 D2
L
Vol = 4/3 p (D1/2) (D2/2) ( L/2) = 4/3 p (D1/2) (D1/2) ( 2D1/2) = p/3 (D3) = 1.047 D3 = D3
More spherical shape,
Vol. = (7/2.4+D) x D3
Ejection fraction3. Modified Simpson’s biplane
method [2D-Echo] 20• Vol= p/4 S ai bi L i=1 20[Difference b/w ai & bi should be less
than 20%]• Most reliable method in case of
regional difference in function• EF calculated comparable to those
measured hemodynamically
Ejection Fraction4. Single plane Area- length
Method
• When only one view is available
• Ventricle is considered symmetrical
• Vol= 0.85 A2
L
Other parameters• Fractional Shortening FS= LVEDD-LVESD x100 LVEDD
• Velocity of Circumferential Fiber shortening [Vcf] Mean Vcf= FS/ LVET
– Mean velocity of ventricular shortening of the minor axis of LV– Ejection phase index of systolic function
Other parameters• Myocardial Performance
index [TEI index] ICT + IRT ET
– Measure of both sys & diastolic function
– Normal <0.4– Strong inverse relationship
with EF– Independent of ventricular
geometryHellenic J Cardiol 2009; 50: 60-6
Other parametersM- mode parameters• EPSS
– >6mm abnormal• Descent of base
– Linear correlation b/w magnitude of annular excursion & LV function
• Rounded appearance of aortic valve closure in late systole
• Rates of systolic thickening of PW
Regional function indices
• WMS– Normal =1– Hypo=2– Akinetic=3– Dyskinetic=4
• WMSI S WMS/N
Deformation analysis• Newer methods of TDI & speckle tracking• Analysis of strain, strain rate or torsion• Strain- change in distance over time• Strain rate- velocity of change over time
Deformation analysis
APEX
Drawbacks
• Strain not uniform from base to apex & in circumferential plane [anterior & lateral wall higher]
• Angle dependency
• Preload dependent
• Heterogenicity within the same myocardium
• Patient to patient variability
• Inter & Intra observer variability
2-D Echo evaluation of LV Function• Most common method used is Simpson’s rule
• Most accurate when LV geometry is normal
• Correlation coefficients ~ 0.75 compared to RNA, cine angiography & autopsy studies Circulation 1979, 60:760-766; Circulation 1980, 61:1119-112
• Limited by reproducibility b/w individual studies
• Improved by tissue harmonic imaging & contrast use.
3D Echocardiography• Direct evaluation of cardiac chamber volumes without the
need for geometric modelling and without the detrimental effects of foreshortened views
• Direct 3D assessment of regional LV wall motion
• Quantification of systolic asynchrony to guide CRT
• 3D color Doppler imaging with volumetric quantification of regurgitant lesions , shunts , and cardiac output
J Am Coll Cardiol 2006; 48:2053– 69
3D Echocardiography
Am J Cardiol 2005;95:809–813
MAGNETIC RESONANCE IMAGING
MRI• Gold standard for assessing LV & RV function
Parameters Comments
Global Function LVEFLV ESV, LV EDV
‘Gold standard’•Simpson’s rule & A-L method•Steady state free precession [SSPE]•Even in patients with abnormal geometry•Low inter & intra observer variability
Cardiol Clin 25 (2007) 15–33
Regional Function RWMA Tissue taggingDisplacement encoding [DENSE}
Wall thickening Center line methodTissue tagging
LV Strain Tissue taggingDENSE
MRI
Assessment by MRI
Gradient echo images of sequential multiple slices of the left ventricle in short-axis planes (from base to apex) are displayed for determining left ventricle volume by Simpson’s rule
Cardiol Clin 25 (2007) 15–33
Assessment by MRI
Tagging of Ventricle for detection of RWMA
2-D displacement Map & Colour coded myocardial strain map
Radiology 2004;233:210–6
Radiology 2004:230:862–71
COMPUTED TOMOGRAPHY
Computed Tomography• EBCT & MDCT has excellent visualization of cardiac
structures.
• Delineation of epicardial & endocardial borders allow accurate & reproducible measure of wall thickness, ESV, EDV.
• ECG gating & image post processing allows cine mode imaging
ECG gated CT
Computed Tomography
Parameters Comments
Global Function LVEFLV ESV, LV EDV
Comparable to RNA Am J Cardiology 1999; 83 (7): 1022-1026
Regional Function Wall Motion Abnormalities and Wall thickening
Stress rest EBCT comparable to Tc SPECT for detecting CAD [EF- 81, 76; EF+RWMA- 88, 100] Am J Cardiology 1998; 81 (6): 682-687
Ventricular Remodeling Comparable to SPECT & Echocardiography J Comput Assist Tomogr 2006; 30 (4): 555-563
Computed Tomography
Radiology 2005; 234:381–390
MRI [Gold Standard] > MDCT>2D-Echo & SPECT
Computed Tomography• Disadvantages
– Radiation risk– Contrast toxicity– Temporal resolution comparably limited
• Used when echo window very poor & MRI contraindicated
NUCLEAR IMAGING
Radionuclide Angiography• Equilibrium method
– ECG gated, data averaged from multiple cardiac cycles, MUGA– 99mTc labeled RBC
• First- pass method– Dynamic acquisition, rapid temporal sampling to look at initial
transit • Principal application is measurement of LVEF
– ICD, ACEI use, Surgical ventricular restoration, Cardiotoxic chemotherapeutics ( Adrimycin therapeutics), Heart Failure Trials
SPECTParameters Comments
Global Function LVEFLV ESV, LV EDV
Regional Function Wall Motion, Wall Thickening
LV contraction Histogram Dysynchrony- heterogenous phase angle distribution
Lung to Heart Ratio Increased lung uptake = incrased PCWP also in MS,MR
Transient Ischemic Dilation Ratio Apparent cavity dilation 20 to diffuse subendocardial ischemia
LV eccentricity & Shape Index
SPECTLV contraction Histogram
SPECT
Overall (n = 718)
Normal (n = 367) SSS<3
Mild (n = 136) SSS 4-8
Moderate (n = 78) SSS 9-13
Severe (n =137) SSS>13
Stress LHR 0.32±0.06 0.30±0.05 0.31±0.05 0.34±0.08 0.36±0.07
Rest LHR 0.31±0.06 0.30±0.05 0.31±0.05 0.32±0.07 0.35±0.06
Diff. LHR 0.006±0.05 0.003±0.046 0.000±0.048 0.017±0.065 0.012±0.053
p value: sLHR vs. rLHR 0.001 0.15 >0.2 0.02 0.008
J Am Coll Cardiol, 2005; 45:1676-1682
Prognostic Value of Lung Sestamibi Uptake in Myocardial Perfusion Imaging of Patients With Known or Suspected Coronary Artery Disease
SPECT
Take Home message
• 2D Echo- most common
• MRI- precision, complex geometry
• Nuclear imaging, CT- used when other indications present
JAmColl Cardiol Img 2008;1:652–62
Thank you