Effects of different ultrasound power application on left ventricular myocardium 2-dimension strain in in vivo open-chest beagle canines

Abstract

Objective To evaluate the left ventricular (LV) myocardial mechanical changes with contrast agent and different power irradiation in open-chest beagle canines. Methods The anesthetized open-chest beagle canines were assigned into two groups randomly: group A (n=6) for baseline, diagnostic ultrasound power irradiation (300 mW) 5 min, combined with contrast agent irradiation 5 min and contrast agent 20 min conditions; group B (n=6) for baseline and intensity ultrasound irradiation (1 W, 2 W and 3 W, 5 min respectively) conditions. The peak circumferential strain (CS), longitudinal strain (LS) and radial strain (RS) of LV myocardial wall were measured and analyzed using a dedicated Syngo velocity vector imaging (VVI) method. Results In group A, the peak CS and LS were increased significantly on diagnostic power irradiation, contrast agent irradiation 5 min and contrast agent 20 min (all P 0.05). In group B, the peak CS and LS were higher on power 1 W than on baseline condition (P 0.05); the peak CS, LS, RS were lower on power 2 W than on baseline condition (P>0.05); the peak of CS, LS were lower on power 3 W than on baseline condition (P 0.05). Conclusions These findings indicate potential positive inotropic effects with diagnostic ultrasound power irradiation 5 min, combined with contrast agent irradiation 5 min, contrast agent 20 min conditions, power 1 W and negative inotropic effects with power 3 W on LV myocardial CS, LS deformation. LV myofiber deformation reactions appear no significant differences on LV myocardial RS deformation in same disturbed setting. Key words: Sonication; Microbubbles; Ventricular function, left; Strain