Intro to Strain Imaging

Atul Jaidka

Slides Available

  • https://slides.com/atulkj/strain
  • https://www.cardioguide.ca/cardio-onc

Background

Anatomy

  • Instead of individual fibres we have multiple bands pulling in different directions
  • Contraction occurring in multiple directions

http://cardiacos.net/wp-content/uploads/ArticulosMedicos/2002/2002-The-Helix-and-the-Heart.pdf

https://ecgwaves.com/topic/deformation-strain-strain-rate-speckle-tracking-echocardiography/

Band Model

What is Strain?

What is Strain?

  • "Deformation of an object that is normalized to its shape"

https://www.asecho.org/wp-content/uploads/2018/01/Anderson-Beginners-Guide-to-Strain.pdf

Directions of Strain

  • Clinically we focus longitudinal strain

https://www.asecho.org/wp-content/uploads/2018/01/Anderson-Beginners-Guide-to-Strain.pdf

How does software determine strain?

Speckle Tracking

  • Myocardium on echo is made up of speckles
  • Software tracks the movement of of these speckles

https://pubmed.ncbi.nlm.nih.gov/15452466/

Global Longitudinal Strain

  • Systolic longitudinal strain for all segments are summed into one value = GLS

https://heart-bmj-com.proxy1.lib.uwo.ca/content/106/18/1438

Global Longitudinal Strain

https://www.asecho.org/wp-content/uploads/2018/01/Anderson-Beginners-Guide-to-Strain.pdf

GE

Acquiring Strain

https://www.sciencedirect.com/science/article/pii/S1936878X1400494X?via%3Dihub

Demonstration

Training

Minimum requirement of 50 studies recommended to achieve competency.

Interpreting the Numbers

ASE 2015

https://asecho.org/wp-content/uploads/2015/01/ChamberQuantification2015.pdf

  • Note when following patients use same machine/software package
  • GLS of -20% is a good general number for healthy people

JACC 2020

https://www.jacc.org/doi/full/10.1016/j.jcmg.2019.07.020

  • GLS worsens as we age
  • Regardless of the company, GLS <16% (absolute value) likely indicates significant myocardial dysfunction

Appropriate Use

Standards for Provision of Echocardiography in Ontario

  • No mention of strain

https://www.corhealthontario.ca/resources-for-healthcare-planners-&-providers/eqi/standards

  • Green: Appropriate use (focus for us)
  • Yellow: May be appropriate
  • Red: Not appropriate

https://www.asecho.org/wp-content/uploads/2019/07/AUC-for-MMI-Nonvalvular-HD-2019.pdf

Cardiotoxic Agents

Maybe Appropriate

  • Initial evaluation of known or suspected HF
  • Inherited or acquired cardiomyopathy
    • restrictive, infiltrative, dilated, hypertrophic
  • ​Valvular disease
    • Mod or greater disease to assess for subclinical LV dysfunction
    • Premise: EF is load dependent and GLS may be more sensitive in picking up dysfunction

Clinical Cases

Approach

https://www.asecho.org/wp-content/uploads/2018/01/Anderson-Beginners-Guide-to-Strain.pdf

Four

Thickened Ventricles

https://bmjopen.bmj.com/content/2/4/e001390

Four

Thickened Ventricles

  • A. Athlete
  • B. HTN
  • C. HCM
  • D. Apical HCM
  • HCM reduces longitudinal strain
  • MRI is best but in Canada it is +++delayed

Clinically important change?

https://www.asecho.org/wp-content/uploads/2018/01/Anderson-Beginners-Guide-to-Strain.pdf

Guidelines don't agree on EF but 15% reduction in GLS considered diagnostic for cardiotoxicity

  • Note: emphasizes the importance of needing baseline strain

55F with HTN, DLD presents with fatigue

https://casereports-bmj-com.proxy1.lib.uwo.ca/content/2012/bcr-2012-006937

55F with HTN, DLD presents with fatigue

  • LVH + RVH
  • Pericardial/Pleural Effusions
  • Plethoric IVC

55F with HTN, DLD presents with fatigue

55F with HTN, DLD presents with fatigue

  • Restrictive filling pattern by MV filling and TDI
  • Apical sparing reduction of GLS -> classic for Amyloid

Take Home Points

  • Strain is available and doable
  • Image quality/optimization is key
  • Need to do enough scans to be competent (50)
  • GLS numbers simplified:
    • 20% is healthy
    • <16% likely is significant myocardial dysfunction

Take Home Points

  • Strain can be clinically useful in:
    • New thickened ventricle
      • HCM vs HTN vs Amyloid
      • Cardio-toxic agent
    • Possible:
      • New/Suspected HF/CM

Resources

Intro to Strain Imaging

By Atul Jaidka

Intro to Strain Imaging

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