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 calculationsV= 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– 1= normal– 2= moderate hypokinesis– 3=severe hypokinesis– 4=akinesis– 5=aneurysm/dyskinesis

• Normal score is 5

ECHOCARDIOGRAPHY

Assesment by Echocardiography

Ejection Fraction

1. 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

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 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

geometryHellenic J Cardiol 2009; 50: 60-6

Other parameters

M- 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- L-L0/L0

• 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 functionParameters 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

SPECT

Parameters Comments Global Function LVEF

LV ESV, LV EDVRegional 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

J Am Coll Cardiol Img 2008;1:652–62

Thank you