Purpose To observe the thrombolytic effect of different ultrasonic frequencies combined with urokinase-containing targeted microbubble contrast agent on rabbit femoral artery,to explore the main influencing factors,and to determine the potential indicators related to recurrent embolism in the microcirculation.Materials and Methods Unilateral femoral arterial thrombosis models were established in the selected 72 New Zealand white rabbits,which were randomly divided into 12 groups,6 rabbits in each group.This study was performed on an experimental combination of three factors and different levels,including different ultrasonic frequencies (1.6,2.2,2.8 MHz),different ultrasonic irradiation time (30 and 60 min),and different urokinase dose (3 and 6 mg).Thrombolysis with urokinase-containing targeted microbubble was performed under low frequency ultrasonic assisted irradiation,the recanalization status of blood vessels was observed,and recurrent embolism in the microcirculation was confirmed by HE staining.Furthermore,rabbit blood samples were collected,with indicators,including 6-keto-prostaglandin F1a (6-keto-PGF1a),Thromboxane B2 (TXB2),P/T ratio (6-keto-PGF1a/TXB2) and P-selectin (SP) being detected.Results All the vessels were recanalized.There was no occurrence of recurrent embolism in the group with ultrasonic frequency of 2.2 MHz,radiation time of 30 min,and urokinase dose of 3 mg.Rabbits' blood vessels were observed to be not completely recanalized in other groups,accompanied with different degree of recurrent embolism in the microcirculation.6-keto-PGF 1 a content of the rabbits in the group without recurrent embolism obviously increased after thrombolysis,and the difference was statistically significant (P＜0.05).While,there was no statistical difference in other indicators (P＞0.05).Conclsion The thrombolysis with ultrasound frequency of 2.2 MHz,irradiation time of 30 min,and urokinase dose of 3 mg could achieve complete recanalization of blood vessels.Under the certain conditions of ultrasonic frequency,irradiation time and urokinase dosage,thrombus can be effectively dissolved.However,there may be risk of recurrent embolism in the microcirculation during thrombolysis process.The increase of 6-keto-PGF 1a content has a certain effect on reducing the formation of recurrent embolism in the microcirculation.%目的 观察不同超声频率联合携尿激酶的靶向微泡造影剂对兔股动脉血栓的溶解作用,探讨影响溶栓作用的主要因素,寻找微循环再栓塞的相关指标.材料与方法 72只新西兰大白兔制作单侧股动脉血栓模型,按照完全随机分组方法分为12组,每组6只.根据超声频率(1.6、2.2、2.8 MHz)、超声照射时间(30、60 min)、尿激酶剂量(3、6mg)3因素不同水平进行实验组合.靶向微泡携带尿激酶在低频超声辅助照射下溶栓,观察血管的溶通情况,并通过HE染色证实有无微循环再栓塞.抽取兔血检测6-酮-前列腺素Fla(6-keto-PGF1a)、血栓素B2 (TXB2)、P/T比值(6-keto-PGF1a/TXB2)及P-选择素(SP)等指标.结果 超声频率2.2 MHz、超声照射时间30 min、尿激酶剂量3 mg组血管全部溶通且无微栓塞发生;其余各组均有未溶通或合并微循环再栓塞发生的情况.溶栓后无微栓塞组的兔6-keto-PGF1a含量明显升高,差异有统计学意义(P＜0.05);而其他指标差异无统计学意义(P＞0.05).结论 超声频率2.2 MHz、超声照射时间30 min、尿激酶低剂量3 mg的条件下溶栓可实现血管的完全溶通.超声频率、超声照射时间及尿激酶剂量一定时可有效溶解血栓,但在溶栓的过程中可能会发生微循环的再栓塞.6-keto-PGF1a含量的升高对降低微循环再栓塞具有一定作用.
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