Comparison of LV Torsion, 2-D Strain and Strain Rate in Small, Medium and Large Breed Dogs
Strain (St), strain rate (SR) and LV torsion have been recognized as newly-developed non-invasive parameters to assess cardiac contractility. Large breed dogs tend to have lower FS compared with small breed dogs. We hypothesized that LV radial motion was less important and that twisting motion may play a more important role in contractility in large breed dogs. If so, quantification of LV twist could be more accurate method to evaluate contractility. The purpose of this study is to assess and compare LV torsion, St and SR in dogs with different body weight (BW) and breeds. Sixty-one clinically healthy dogs of 7 different breeds were used. Dogs were divided into 3 groups; small, medium and large breed. Speckle tracking imaging (Vivid 7 dimension, GE) was used to obtain LV circumferential and radial St and SR, along with systolic rotation, rotation rate and torsion in addition to standard M-mode measurements.
All parameters of 2-D St and SR except for peak systolic radial St negatively correlated with BW and body surface area (BSA). Parameters for torsion and rotation also negatively correlated with BW and BSA, which revealed that rotating motion was not predominant in systolic function in large breed dogs compared with smaller breed dogs. Stroke index derived from stroke volume divided by BSA did not demonstrate any correlation with BW or BSA. Therefore, a relatively lower LV motion in large breed dogs effectively ejected sufficient cardiac output. Peak systolic radial St may be a good parameter for contractility without influence of BW.