Effect Of Long Pulse Ultrasound Combined With Microbubbles And Rt-PA In Thrombotic Embolization Model Of Rat's Common Carotid Artery

Objective:This study aims at exploring efficacy of long pulse ultrasound combined with microbubbles and rt-PA in thrombolic embolization model of rat's common carotid artery.Methods:The total occlusion models with platelet-rich thrombus were induced by using filter paper saturated with 10%ferric chloride in rat's common carotid artery.We used therapeutic ultrasound(frequency 1MHz,mechanical index 0.6,pulse length 1000cycle)and chose two different duty cycles(0.03%and 10%).Forty-two Sprague Dawley(SD)male rats were randomly divided into seven groups which contain one control group and six treatment groups(n=6):(1)control group;(2)recombinant tissue-type plasminogen activator(rt-PA)group;(3)high duty cycle ultrasound(US)combined with microbubbles(MB);(4)low duty cycle US combined with rt-PA group;(5)high duty cycle US combined with rt-PA group;(6)low duty cycle US with MB+rt-PA group;(7)high duty cycle US with MB+rt-PA group.The total treatment period last for 20 minutes and thrombolytic effects including recanalization rate and recanalization grade were evaluated with two-dimensional and color Doppler ultrasound.Results:In our study,thrombolysis in terms of recanalization rate and recanalization grade was observed in the treated group,except the control group,rt-PA group and high US(H)+MB group.Compared to the control group,there was a significant recanalization in US+rt-PA group(66.7%VS 0%,p<0.01)in both different duty cycles.However,the recanalization rate and recanalization grade in US+MB+rt-PA group was higher than US+rt-PA group no matter which duty cycle used(US(L):83.3%VS 66.7%;US(H):100%VS 66.7%).Compared to low duty cycle ultrasound group,high duty cycle ultrasound showed better recanalization grade,with or without microbubble(US+rt-PA:66.7%VS 33.3%,US+MB+rt-PA:100%VS 66.7%).Conclusion:Long pules ultrasound combined with rt-PA was a relatively effective approach for the total occlusion model by platelet-rich thrombus.Efficacy of US+MB+rt-PA was greater than US+rt-PA,especially in high duty cycle groups.