Objective To investigate the thrombolytic effect of EKOS

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ultrasound catheter combined withintrathrombotic microbubbles（MB）on urokinase（UK）thrombolysis.MethodsThe peak negative pressure（PNP）of the EKOS

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catheter was measured by hydrophone method.Ninety bovine thrombus samples in vitro were randomly divided into six groups:ultrasound（US）+MB+UK（combined group）

US+UK group

US+MB group

US group

UK group and control group

each grouphas 15 samples. The thrombus quality of each group was weighed before and after thrombolysis

and thrombolysis rate wascalculated and compared.After treatment

the thrombus in each group wasstained with HE

and the distribution of erythrocyte andfibrin was observed under a light microscope.ResultsThe PNP of EKOS

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catheter varied irregularly within the range of 0.4～6.4 MPa.The thrombolysis rate of combined group（41.9±4.5）% was close to that of US+UK group（42.0±3.3）%

which weresignificantly higher than that of the other groups（all P

<

0.05）.The thrombolysis rate of US+MB group was（28.4±3.3）%

comparedwith（27.8±3.1）% in UK group

there was no significant difference between the two groups

which were significantly higher thanthat of US group（23.9 ±3.0）% and control group（17.5±3.7）%

there were significant difference（both P

<

0.05）.Histologicalexamination of the thrombus in combined group and US+UK group showed that the thrombus contacting with EKOS

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catheter wasmore disintegrated

and the distribution of red blood cells was more sparse than other groups.Conclusion EKOS

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catheter canobviously improve the thrombolysis rate of UK to bovine thrombus in vitro

however

MB has no significant effect on thrombolysis rate.