900am Dr Feigenbaum Strain Echocardiography

A Practical Approach to Using Strain Echocardiography to Evaluate the Left Ventricle Harvey Feigenbaum MD No conflicts of interest to report

Echocardiography 2020: Opportunities and Challenges Alan S. Pearlman, MD, FASE, Editor JASE JASE Volume 23, Issue 8, Pages 898-900, August 2010 •

To me, an additional concern is that using only older “tried and true” technology is absolutely the antithesis of the exciting opportunities offered by the array of diagnostic tools available to the echocardiographer, as Dr. Zoghbi (ASE keynote address) so clearly demonstrated. If echocardiographers are to stand still, depend on standard 2D echo imaging using equipment produced a decade ago and not upgraded since, perform “ejectionfractionograms”, focus primarily on the left ventricle and simply “eyeball” the other chambers, and avoid new methods such as strain imaging and contrast echo because they are perceived as “a waste of time”, then I fear that echocardiography will be passed by. As the dinosaurs illustrated, we need to adapt and continue to evolve, or face the consequences.

Echo Assessment of Left Ventricle • • • • • • • •

Linear dimensions: LVIDd LVIDs FS Areas: FAC Volumes: LVVd LVVs EF 2D Regional Wall Motion M-mode motion of walls, septum & valves Doppler measurements: Hemodynamics, MPI Tissue Doppler: Annular motion Strain and Strain Rate

Strain/Strain Rate • The relationship between two points as if they were connected by a rubber band • When the two points move away from each other (e.g. diastole) strain is increased (positive strain). • When the two points move toward each other (e.g. systole) strain is decreased (negative strain).

Strain Rate • Using tissue Doppler which is a form of pulsed Doppler, specific points in the myocardium can be identified • Tracking these point permits the meassurement of strain • Since Doppler is velocity or distance/time, the initial measurement is strain rate • Integrating strain rate gives strain

Strain Rate Imaging L

Strain Rate = Vel (L) – Vel(L + L) L

L

Strain Rate = Rate of change of length of tissue region or shortening velocity per fiber length (1/sec) Negative SR = shortenng Positive SR = lengthening

Changes in Strain Rate with Ischemia

Limitations With Doppler Based Strain Rate • As with all Doppler applications, strain rate is angle dependent • The Doppler strain rate sample volume is fixed while the myocardium is moving • Strain rate is the derivative of strain and tends to be noisy • The strain rate “curved M-mode” display is only semi quantitative, noisy, can be difficult to interpret and is not popular

Strain

2D and 3D Speckle Tracking

Speckle Tracking • The raw (radiofrequency or RF) ultrasonc image consists of numerous random speckles • Any given point on an ultrasonic image can be identified by a unique speckle pattern • Using these speckle patterns (speckle tracking) to identify specific points in the myocardium, strain can be recorded • Since 2D echo is distance, the initial measurement is strain • The derivative of strain will give strain rate

Normal Strain Displays Quantitative Parametric Overlay Wave Forms Curved M-mode

Normal Strain Bullseye Presentation (base of LV outer ring, apex at center) All segments red and all but one in upper teens or 20’s

Abnormal Strain Quantitative Parametric Overlay Wave Forms Curved M-mode

Abnormal Strain Bullseye presentation Several segments light red or pink and of lower values

Advantages of Strain/Strain Rate Imaging • Avoids some of the limitations of wall motion analysis: tethering, off-axis false positive, subtle wall motion • More sensitive in detecting myocardial dysfunction • Quantitative • Technically feasible with stress • Closer to assessing true regional contraction than is wall motion or Tissue Doppler • May assist in assessing viability with stress and at rest • Represents an independent supplement to wall motion for LV mechanics

ASE Open Forum Longitudinal strain is a great tool to evaluate the real systolic function especially in cases like HCM. This population appears to have a normal EF but the global longitudinal strain is decreased (