Abstract 12781: A New High Resolution 3D Echo Based Strain Method Gives Robust Characterization of Myocardial Mechanics: An In Vitro Validation Study
Background: Speckle tracking based strain has been shown to be an important tool in evaluation of segmental left ventricular (LV) dysfunction and dyssynchrony. We tested the accuracy and feasibility of a new 3D echo based feature tracking strain methods implemented in a GE Vivid E9 and EchoPac PC®.
Methods: We studied 10 freshly harvested pig hearts. Each heart was mounted in a water bath to facilitate ultrasound scanning and connected to a calibrated pulsatile pump through a balloon secured in the LV cavity. Three sonomicrometry (sono) crystals were secured into the myocardium on the anterior of the LV as a triangle at mid cavity level, with crystals 1 & 2 in long axis and 2 & 3 along the LV short axis. Each heart was driven passively by a pump delivering 5 different calibrated stroke volumes (SV; 30–70ml) at a constant rate of 50bpm. Cardiac motion was scanned from the apical view to acquire gated full volume 3D image loops on a Vivid E9 ultrasound system with a new higher frequency matrix probe. Sector width, volume size and depth of scanning were optimized to obtain the volume rate >25/sec. Sono data was also obtained at a sampling rate >250/sec. The study was repeated in each heart model after injecting 2ml of gluteraldehyde into the myocardium between crystals to simulate infarct. Image data was analyzed in EchoPac PC for 3D segmental strain. Sono data was analyzed for displacement between crystals to compute strain in corresponding segments.
Results: Increase in SV resulted in increased stretching of myocardium that was detected by both sonomicrometry and the 3D echo based method. 3D echo slightly overestimated the 3D strain values (5.0 ± 3.5%) when compared to sonomicrometry in corresponding segments, but both methods showed a strong positive linear correlation. (r = 0.85). Simulated infarct showed significantly lower strain values by both methods.
Conclusions: In our phantom study, 3D strain was an accurate imaging based method for computing strain and defining infarct.
- © 2010 by American Heart Association, Inc.