Effects of different ultrasound power application on left ventricular rotation and twist in vivo open-chest beagle canines / 中华超声影像学杂志

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 ) compared with baseline condition ;LV subendo-twi was higher than subepi-twi in group A under the same condition ( P < 0 .05) . In group B ,LV subendo-twi ,subepi-twi and subendo-rot ,subepi-rot of BL and AL on power 1 W ,2 W were higher and subendo-twi ,subepi-twi on power 3 W were lower than those on baseline condition ( P < 0 .05) ;There was no difference in subendo-rot and subepi-rot of LV BL compared with baseline condition ( 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 .