Echocardiographic Assessment of LV Systolic Function

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Echocardiographic Assessment of LV Systolic
Function

• 
  Ryan Tsuda, MD

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Causes of LV Systolic Dysfunction

• CAD
• HTN
• Cardiomyopathy (iDCM, HCM, Etoh, Peripartum,
  Viral, Infiltrative, Toxins, Thyroid Dz.,
  Tachyarrythmias)
• Valvular Disease

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Dimensions and Area

• Parasternal short-axis at level of papillary
  muscles
• Parasternal long-axis
• Apical 4-chamber
• Apical 2-chamber

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2D Clips
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LV Mass Quantification

• M-mode
• Area-length method
• Truncated ellipsoid method
• Subjective assessment

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LV Mass Quantification

• 2D M-Mode method using parasternal short axis
  view or parasternal long axis view
• Assumes that LV is ellipsoid (21 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.

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LV Mass Quantification

• Penn convention formula (Another form of the cube
  equation)
• LV mass 1.04(IVS LVID PWT)3
• (LVID)3 13.6 g
• NL LV mass index for males 93 /- 22 g/m2
• NL LV mass index for females 76 /- 18
  g/m2

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RWT 2(PWT/LVID)
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LV Volume Measurement With M-Mode

• Assuming nl ventricle morphology
• V (LVID)3
• If ventricle is dilated (spherical)
• Teichholz equation
• Vdiastole 7/(2.4 LVID) x LVID3
  

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LV Systolic Function Variables

• LVEDD LVESD
• FS -------------------- X 100
• LVEDD
• Percent change in LV dimension with systolic
  contraction
• FS approximates EF if there are no significant
  wall motion abnormalities
• SV EDV - ESV
  CO SV x HR
• EDV - ESV
• EF ----------------- X 100
• EDV

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How do we quantify LV function?

• M-Mode
• Modified Simpsons Method
• Single plane area-length method
• Velocity of Circumferential Shortening
• Mitral Annular Excursion
• E-point to septal separation
• Rate of rise of MR jet
• Index of myocardial performance
• Subjective assessment

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M-Mode Quantification

• Use Parasternal Short-Axis (Mayo) or Long-Axis
  (ASE) views to measure LVEDD and LVESD
• May take several measurements at different levels
  and calculate average
• Assumes no significant regional wall motion
  abnormalities present.

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M-Mode Quantification

• Uncorrected (LVEDD)2 - (LVESD)2
• LVEF ----------------------
  -------- X 100
• 
  (LVEDD)2
• If apical contractility is normal (Quinones
  group)
• Corrected
• LVEF Unc LVEF ((100 Unc LVEF) X
  15)
• 5 hypokinetic, 0 akinetic, -5 dyskinetic, -10
  aneurysm

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Modified Simpsons Method (Disc Summation
Method)

• Use apical 4 chamber and apical 2 chamber views
  to measure dimension and area
• Trace borders manually or by acoustic
  quantification
• Divides area into 20 cylinders of equal height

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Acoustic Quantification

• Automatic detection of blood-tissue border based
  on integrated backscatter analysis
• This is the difference in amplitude of
  backscatter between the myocardial wall and blood
• Blood-tissue border is recognized by echo
  machine, and marked with dots

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Acoustic Quantification

• Area of study is quantified continuously in real
  time throughout cardiac cycle
• Therefore, the change in LV cavity area or volume
  with systolic contraction is calculated
  instantaneously, thereby providing LVEF.
• AQ limited by its dependency on echocardiographic
  gain and image quality
• Echo gain Amplification of the returning RF
  signal which weakens with distance i.e. an
  increased echodensity is seen as tissue,
  thereby decreasing accuracyLateral wall is
  especially subject to error.

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Derivation of 3.14(R)2 X D
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Modified Simpsons Method

• EDV ESV
• LVEF --------------- X 100
• EDV

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Single plane area-length method
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Velocity of Circumferential shortening

• Vcf is the mean velocity of LV shortening through
  the minor axis
• Vcf FS/ET
• ET is the time between LV isovolumetric
  contraction and isovolumetric relaxation
• Measure by obtaining M-mode of AV opening to AV
  closure, aortic flow by doppler, or by an
  external pulse recording of carotid artery
• NL values are gt 1.0 c/s
• Slow Vcf may suggest diminished systolic function

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Mitral Annular Excursion toward LV Apex

• 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 lt 8 mm, the EF is likely lt 50

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Normal E point to septal separation is lt 6
mm With reduced lvef, EPSS may be increased.
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CW doppler to measure rate of rise of MR jet may
correlate to LVEF A slow rate of rise may
indicate poor systolic function Must have MR
present, and good doppler study present (more
difficult with eccentric jets)
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Index of Myocardial Performance (mayo
clinics) Uses systolic and diastolic time
intervals to evaluate global ventricular
performance Systolic dysfunction causes prolonged
isovolumetric contraction time (ICT) and a
shortened ejection time (ET). Systolic and
Diastolic dysfunction causes a prolonged
isovolumetric relaxation time (IRT) IMP (ICT
IRT)/ET
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Index of Myocardial Performance

• Normal LV 0.39 /- 0.05
• LV, DCM 0.59 /- 0.10
• Normal RV 0.28 /- 0.04
• Primary Pulm Htn 0.93 /- 0.34
• Use PW of AV inflow signal, or CW to get AV
  regurgitant signal..Also need to measure
  interval between AV closure and opening (AVco).
• Then, need to use PW or CW to capture semilunar
  outflow signal to measure ejection time (ET).
  After all of this, IMP can be calculated.
• IMP (AVco ET)/ET

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Assessment of Regional Function

• Based on grading wall motion divided into the 16
  (17) segment model as proposed by the American
  Society of Echocardiography
• Each segment can be viewed in multiple
  tomographic planes

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Assessment of Regional Function

• 1 normal
• 2 hypokinesis
• 3 akinesis
• 4 dyskinesis
• 5 aneurysmal
• WMSI Sum of scores / Number of visualized
  segments
• WMSI gt 1.7 may suggest perfusion defect gt 20

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Assessment of Regional Function

• 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

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2D Clips
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Doppler Tissue Imaging for Wall Motion Analysis

• Myocardium is color-coded according to velocity
• On P-Short Axis view, normal LV anterior wall
  motion during systole is blue (away from
  transducer), and the posterior wall motion is red
  (toward transducer) akinesis will have no color

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Color Kinesis by 2D-Echo to Evaluate Wall Motion

• Real time color-coded display of LV endocardial
  motion on sequential frames
• Color is added to pixels that are identified as
  changing from blood to tissue in systole
• Create a color map of endocardial border
• This method limited by poor endocardial
  definition and translational motion of heart.

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Summary

• LV Mass Quantification M-mode, Area-length
  method, Truncated ellipsoid method, and
  Subjective assessment.
• LV Volume Quantification M-mode, Subjective
  assessment
• LV Function Quantification Modified Simpsons
  and Subjective Assessment by region.Also by
  M-mode, Single plane area length method, Velocity
  of Circumferential Shortening, Mitral Annular
  Excursion, EPSS, Rate of Rise of MR jet, Index of
  myocardial performance, etc..

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Summary

• Modalities limited by quality of echo windows,
  accurate measurements are based on the ability to
  identify and capture ideal axis (recognize
  misleading off axis/tangential slices), and of
  course, echocardiographer experience..

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Eye Candy
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References

• Oh, Jae K., The Echo Manual 2nd edition, 1999, p.
  37-43.
• Kerut, Edmund, Handbook of Echo- Doppler
  Interpretation, 1996, p. 54-63.
• Atlas of Echocardiography Website
• Braunwald, Eugene, Heart Disease 6th edition, p.
  165-169.