Effects of different ultrasound power application on left ventricular rotation and twist in vivo open-chest beagle canines

Abstract

Objective To evaluate left ventricular (LV) myocardial mechanical rotation and twist with contrast agent and different power irradiation in open-chest beagle canines by ultrasound velocity vector images (VVI). 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 standard short-axis gray-scale views at basal level (BL), and apical level(AL) during three complete cardiac cycles in open-chest beagle canine models were acquired. The peak subendomyocardium rotation (subendo-rot), subepimyocardium rotation (subepi-rot) of BL and AL were analyzed using a dedicated Syngo velocity vector imaging (VVI) method and LV subendomyocardium twist (subendo-twi) and subepimyocardium twist (subepi-twi) were defined as apical subendo-rot/subepi-rot-basal subendo-rot/subepi-rot. Results In group A, the LV subendo-twi, subepi-twi, subendo-rot and subepi-rot of BL and AL in the most of segments were significant different on diagnostic power irradiation, contrast agent irradiation 5 min and contrast agent 20 min (P 0.05); subendo-rot and subepi-rot of LV AL were different compared with those on baseline condition (P<0.05); LV subendo-twi and subepi-twi in group B under the same condition were significant difference (P<0.05). Conclusions LV rotation and twist increase on diagnostic ultrasound power irradiation 5 min, combined with contrast agent irradiation 5 min, contrast agent 20 min conditions, 1 W and 2 W; LV twist and AL rotation decrease on ultrasound power 3 W, but BL rotation is not affected on ultrasound power 3 W. Key words: Sonication; Ventricular function, left; Rotation; Twist