Atul Jaidka
Cardiologist | Unity Health - St. Joseph's Hospital
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
- New thickened ventricle
Resources
Intro to Strain Imaging
By Atul Jaidka
