Assessment of LV Systolic Function Dr Nithin P G

Overview Normal LV contraction Global & regional indices of LV systolic Function Angiographic assessments Echocardiography MRI Computed Tomography Nuclear Imaging Take home message

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 Reproducibility using different imaging techniques Extensive documentation of its clinical usefulness.

Ejection fraction Drawbacks 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

ESPVR ESPVR 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 calculations V= 4/3 p [L/2] [M/2] [N/2] = p /6 LMN ARAO= p [LRAO/2] [ M/2]= p [LRAO][M]/4 ALAO= 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 indices Angiographic wall motion score Normal score is 5 2= moderate hypokinesis 3=severe hypokinesis 4=akinesis 5=aneurysm/dyskinesis Normal score is 5

Echocardiography

Assesment by Echocardiography Ejection Fraction M- mode EF= LVEDD2-LVESD2 x100 LVEDD2 EFc= [(1-%EF) x % DL] + %EF DL=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 fraction 2. D3 method 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 L D1 D2

Ejection fraction 3. 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 Fraction 4. 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 geometry Hellenic J Cardiol 2009; 50: 60-6

Other parameters M- mode parameters EPSS Descent of base >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- L-L0/L0 Strain rate- velocity of change over time

Deformation analysis 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 APEX

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 LVEF LV 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 tagging Displacement encoding [DENSE} Wall thickening Center line method LV Strain DENSE

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 Radiology 2004;233:210–6 Tagging of Ventricle for detection of RWMA Radiology 2004;233:210–6 2-D displacement Map & Colour coded myocardial strain map 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 LVEF LV 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 MRI [Gold Standard] > MDCT>2D-Echo & SPECT Radiology 2005; 234:381–390

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

SPECT Parameters Comments Global Function LVEF LV 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

SPECT LV contraction Histogram

SPECT Prognostic Value of Lung Sestamibi Uptake in Myocardial Perfusion Imaging of Patients With Known or Suspected Coronary Artery Disease 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 0.32±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

SPECT

Take Home message 2D Echo- most common MRI- precision, complex geometry Nuclear imaging, CT- used when other indications present J Am Coll Cardiol Img 2008;1:652–62

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