椎基底动脉缺血性卒中急诊动脉溶栓疗效分析

目的观察椎基底动脉缺血性卒中急诊动脉溶栓的安全性和疗效。方法对急性椎基底动脉系统缺血性卒中急诊脑血管造影显示，基底动脉主干或其较大主要分支闭塞17例，双侧椎动脉闭塞4例，一侧椎动脉闭塞，另一侧椎动脉或基底动脉严重狭窄5例，未见血管闭塞19例。符合动脉溶栓条件，实施接触性动脉溶栓的病人45例。结果45例病人溶栓后血管成功再通17例（65，4％），血管不成功再通9例（34.6％）。30例疗效好。溶栓后发现基础血管中重度狭窄5例，溶栓后近期复发1例，颅内出血2例，死亡5例，病死率11％。结论椎基底动脉缺血性卒中急诊动脉溶栓是有效的治疗方法，可增加血管再通率，改善椎基底动脉缺血性卒中病人的预后。     

动脉内溶栓联合支架治疗基底动脉闭塞临床报道

目的探讨溶栓后即刻置入支架的方法治疗急性椎基底动脉系统卒中溶栓术后血管重新闭塞的有效性和安全性。方法回顾性分析北京宣武医院2003年7月-2004年12月采用动脉内溶栓加支架置入治疗的7例脑卒中患者的临床资料，采用尿激酶超选择动脉溶栓，溶栓后对血管狭窄行支架成形术。结果7例溶栓后均再通。基底动脉尾段狭窄1例，主干狭窄4例，头段狭窄2例．动脉狭窄率平均为85％．即刻置入冠脉支架。置入支架后造影显示血管形态良好．残留狭窄率小于20％。术后复查点片状脑出血2例。术后症状好转或消失6例，围手术期死亡1例。结论超选择动脉溶栓联合支架治疗能够防止血管再闭塞及卒中复发，改善病人预后。     

超选择动脉溶栓及血管成形术治疗急性脑梗死的临床研究

目的：探讨超选择经动脉尿激酶（UK）溶栓及血管成形术（PTA）治疗急性脑梗死的临床疗效。方法：随机取56例急性脑梗死病人为研究组，行超选择动脉溶栓及PTA治疗，取脑梗死病人为对照组，行UK静脉溶栓治疗，复查血管再通率，比较两组临床疗效及并发症。结果：颈内动脉（ICA），大脑中动脉（MCA），椎基底动脉闭塞血管再通率分别为50％，95％，和100％，PTA组6例中，ICA2例，椎基底动脉4例，均有血管再通，治疗后研究组神经功能缺损（NFD）评分，语言功能障碍恢复，3个月后临床神经功能均好于对照组，研究组并发症的数量和严重程度均明显低于对照组。结论：尿激酶超选择动脉溶栓及血管成形术是治疗急性脑梗死安全有效的方法，血管内精巧细致的超滑导丝和球囊扩张等机械性作用显弥补了单纯溶栓药物治疗的不足。     

尿激酶动脉内溶栓联合血管内干预治疗急性脑梗死分析

目的分析尿激酶动脉内溶栓联合血管内干预治疗急性脑梗死的疗效和安全性。方法回顾分析我科住院治疗13例患者进行尿激酶动脉内溶栓及血管内干预治疗的急性脑梗死患者临床资料。结果 13例患者中,颈动脉系统病变11例,其中颈内动脉闭塞2例,大脑中动脉主干及分支闭塞8例,大脑前动脉闭塞1例(包含脑血管造影未见异常者3例),椎基底动脉闭塞2例。溶栓开始时间3～12h,平均7.5h,其中10例在6h内开始。使用尿激酶30万～100万U,平均70万U。溶栓后2例给予血管内支架治疗,4例给予球囊扩张血管成形治疗。基本痊愈5例,显著进步5例,无效3例。闭塞血管成功再通7例,未成功再通3例。并发脑出血1例,死亡1例,无并发消化道出血等其他情况。结论对急性脑梗死患者进行尿激酶动脉内溶栓联合血管内干预治疗是安全有效的。     

Solitaire-AB型支架取栓术治疗急性椎-基底动脉闭塞的疗效

目的 探讨Solitaire-AB型支架取栓术治疗急性椎-基底动脉闭塞的有效性及安全性。方法 回顾性分析2016年1月至2019年7月采用Solitaire-AB型支架取栓术治疗10例急性椎-基底动脉急性闭塞的临床资料。脑梗死溶栓（TICI）分级≥2b级认为血管再通。结果 10例取栓后均获得血管再通,TICI分级3级。1例合并枕叶少量出血,1周后复查出血消失。出院时mRS评分0分3例,1分1例,2分3例,3分1例,4分1例,死亡1例。出院3个月,mRS评分0分4例,1分3例,2分2例。结论 急性椎-基底动脉闭塞采取Solitaire-AB型支架取栓血流再通率高,能显著改善病人的预后。     

动脉内溶栓治疗急性缺血性脑卒中的临床分析

目的:探讨使用动脉内溶栓方法治疗急性缺血性脑卒中的效果。方法:回顾138例急性缺血性脑卒中患者,发病距接受治疗的时间为3～24h,采取超选择性动脉溶栓。结果:颈内动脉闭塞22例,大脑中动脉主干闭塞38例,大脑中动脉分支闭塞33例,大脑前动脉闭塞1例,椎基底动脉系统血管闭塞12支。脑血管造影未见异常32例。闭塞血管再通者,颈内动脉12例;大脑中动脉24例;大脑中动脉分支21例;椎基底动脉8例。8例患者因明显血管狭窄,治疗后予以球囊扩张,支架植入术。临床症状完全恢复或明显好转83例,溶栓后脑出血患者5例。结论:超选择动脉内溶栓是治疗急性缺血性脑卒中的有效方法。     

急性缺血性脑卒中动脉内溶栓治疗临床分析

目的探讨急性缺血性脑卒中动脉内溶栓治疗效果。方法411例急性缺血性脑卒中患者,男238例,女173例,平均为(64±11)岁,发病距接受治疗的时间为2-24 h,采取超选择性接触性溶栓。尿激酶用微量泵以1万u/min持续泵入,总量为80- 130万u。在泵入尿激酶的过程中,通过导引导管造影,了解闭塞血管再通情况。结果颈动脉系统血管闭塞273支,椎-基底动脉系统闭塞132支。脑血管造影未见明显异常78例。颈内动脉闭塞再通率为54.72%;大脑中动脉闭塞再通率为65.18%。大脑中动脉分支闭塞再通率为61.68%。椎-基底动脉系统闭塞再通率为67.42%。并有35例因明显的血管狭窄而给予球囊扩张、支架置入术。临床症状完全恢复正常或有明显好转的247例,为60.10%。结论我们认为动脉内接触性溶栓治疗急性脑梗塞还是很值得进行的。随着溶栓经验的积累,溶栓药的开发,脑保护剂的应用,总有效率会不断提高。     

动脉内接触性溶栓治疗急性缺血性脑卒中

目的探讨急性缺血性脑卒中动脉内接触性溶栓治疗的安全性和有效性。方法对178例急性缺血性脑卒中病人在起病后2～24h进行尿激酶超选择性动脉内接触性溶栓,尿激酶用量50～130万U(平均85万U)。结果颈内动脉系统血管闭塞117例,椎-基底动脉系统闭塞30例,脑血管造影未见明显异常31例。闭塞的颈内动脉再通14例,大脑中动脉再通29例,大脑中动脉分支再通30例,椎-基底动脉系统再通20例。11例因血管狭窄明显,溶栓后给予球囊扩张、支架置入术。临床症状完全恢复正常或明显好转108例,并发脑出血6例,消化道出血15例。结论超选动脉内接触性溶栓可使血栓局部迅速达到较高的血药浓度,疗效好,见效快,用药总量小,并发症少。     

微创方案治疗急性椎基底动脉闭塞性脑梗死临床研究

目的探讨静脉溶栓、动脉溶栓及机械取栓方案对急性椎基底动脉闭塞性脑梗死患者近远期疗效及安全性的影响。方法选取焦作煤业集团中央医院2016-01-2018-01收治急性椎基底动脉闭塞性脑梗死患者共135例,以随机数字表法分为A组(45例)、B组(45例)及C组(45例),分别采用静脉溶栓、动脉溶栓及机械取栓方案治疗,比较3组血管再通率、NIHSS评分改善良好率、随访预后改善率、随访病死率及颅内症状性出血发生率。结果 C组血管再通率和NIHSS评分改善良好率均显著高于A组、B组(P0.05);B组血管再通率和NIHSS评分改善良好率均显著高于A组(P0.05);C组随访预后改善率显著高于A组、B组(P0.05);3组随访病死率比较差异无显著性(P0.05);同时C组术后颅内症状性出血发生率显著低于A组、B组(P0.05)。结论机械取栓方案治疗急性椎基底动脉闭塞性脑梗死在近远期疗效和安全性方面均显著优于静脉溶栓、动脉溶栓,更具临床应用价值。     

重组组织型纤溶酶原激活剂动脉内溶栓和血管内支架成形术治疗急性脑梗死

目的 评价重组组织型纤溶酶原激活剂(r-TPA)超选择动脉内溶栓和血管内支架成形术治疗急性脑梗死的临床疗效.方法 回顾性分析45例急性脑梗死病人的临床资料,其中颈内动脉闭塞16例,大脑中动脉闭塞25例,椎-基底动脉闭塞4例.将微导管超选择送至血管闭塞部位,注入r-TPA行动脉内溶栓.其中血管明显狭窄7例,溶栓后采用支架血管内成形术.结果 溶栓后完全再通31例,部分再通14例.治疗前欧洲卒中评分(European stroke scale,ESS)为(55.50±13.25),治疗后7dESS评分为(90.85±15.36),两者有显著性差异(P＜0.01).7例血管明显狭窄者,支架置入术后血管残余狭窄＜16％.结论 r-TPA早期超选择动脉内接触性溶栓,是治疗急性脑梗死的有效方法之一.对合并严重动脉狭窄的病人,动脉内溶栓结合血管内支架成形术安全可行.     

时间窗超过3h急性缺血性卒中患者动脉溶栓治疗观察

目的 评价时间窗超过3 h的急性缺血性卒中患者动脉溶栓治疗的疗效及影响因素.方法 选择法国南锡大学中心医院神经影像科自2008年1月至2009年1月收治的16例急性缺血性卒中患者(时间窗均达到或超过3 h,颈内动脉系统卒中时间窗不超过6 h,椎基底动脉系统卒中时间窗不超过24h.昏迷不超过6 h),行动脉内药物联合机械溶栓治疗,分析不同因素对疗效的影响.结果 7例患者闭塞血管达到完全再通,7例达到部分再通,另有2例闭塞血管未再通,再通率为87.5%.患者动脉溶栓后与溶栓前NIHSS评分比较明显降低.时间窗大于5 h的前循环系统闭塞患者溶栓前后NIHSS评分无改善,与时间窗较短患者相比较,出院时mRS评分明显较高.5例颈内动脉闭塞患者溶栓前后NIHSS评分无改善,与9例大脑中动脉闭塞患者、2例基底动脉闭塞患者相比预后较差.4例患者溶栓后24h出现症状性颅内出血,3例为颈内动脉闭塞,1例死亡.1例溶栓后发生血管再闭,但因侧支循环血流丰富,最终临床预后仍较好.结论 对于时间窗超过3 h大脑中动脉和基底动脉闭塞急性缺血性卒中患者,动脉溶栓可使闭塞血管达到较高的再通率,短期内使临床神经功能恢复,改善临床结局.临床应用动脉溶栓时应注意个体化选择性治疗,评价其疗效需结合时间窗、血管闭塞部位、侧支循环、并发症等因素,避免出血等并发症.

Abstract：

Objective To evaluate the efficacy of intra-arterial hrombolytic therapy in patients with acute ischemic stroke having their time window over 3 h and analyze its influencing factors.Methods Sixteen patients with acute ischemic stroke having their time window over 3 h, admitted to Department of Neuroradiology of Central Hospital of Nancy University from January 2008 to January 2009, were treated by intra-arterial thrombolysis using chemical (rt-PA) and mechanical technique. These patients had carotid stroke for less than 3 h, vertebrobasilar stroke for less than 24 h or coma for less than 6 h. According to the images of DSA, the recanalization after thrombolysis was evaluated by thrombolysis in cerebral infarction (TICI) grades. CT scans 24 h after thrombolysis were operated to detect the hemorrhage complications. NIHSS at baseline and 24 h after thrombolysis and modified Rankin Scale (mRS) were recorded to evaluate the clinical efficacy. Results After intra-arterial thrombolysis, 7 (43.75%) in 16 patients got totally recanalization (TICI grade 3), another 7 partial recanalization (TICI grade 2), and the left 2 patients failed in recanalization (TICI grade 1); the total recanalization rate was 87.5%. A significant reduction of NIHSS scores after the thrombolysis was noted as compared with that before the thrombolysis. The atients with occlusion of anterior ciculation having time window over 5 h enjoyed no reduction of NIHSS scores after thrombolysis; mRS scores in patients having time window over 5 h were ignificantly higher as compared with those in patients having time window less than 5 h.The patients having ICA occlusion (n=5) had no reduction of NIHSS scores after thrombolysis, and enjoyed poorer prognosis as compared with whose occlusion lay in the middle cerebral artery (MCA,n=9) and basilar artery (BA, n=2). By CT scan 24 h after thrombolysis, 4 patients were detected with symptomatic intra cerebral hemorrhage (ICH, 25%) and all of them with occlusion in the internal carotid artery system: 1 patient with occlusion in MCA died of cerebral hernia causing by the large hematoma;the other 3 were all occlusion in ICA. Although reocclusion after thrombolysis occurred, 1 patient was benefitted from the affluent collateral perfusion and got a good prognosis. Conclusion For patientswith BA and MCA occlusion having time window over 3 h, intra-arterial thrombolytic therapy is effective and selective resulting from their high recanalization rate, improvement of neurological function and clinical end. The therapy should be individually chosen; mutiple factors as time window of stroke,location of stroke, ompensatory circulation and complications should be considered in evaluating the efficacy; and the hemorrhage complications should be avoided.     

时间窗超过3h急性缺血性卒中患者动脉溶栓治疗观察

目的 评价时间窗超过3 h的急性缺血性卒中患者动脉溶栓治疗的疗效及影响因素.方法 选择法国南锡大学中心医院神经影像科自2008年1月至2009年1月收治的16例急性缺血性卒中患者(时间窗均达到或超过3 h,颈内动脉系统卒中时间窗不超过6 h,椎基底动脉系统卒中时间窗不超过24h.昏迷不超过6 h),行动脉内药物联合机械溶栓治疗,分析不同因素对疗效的影响.结果 7例患者闭塞血管达到完全再通,7例达到部分再通,另有2例闭塞血管未再通,再通率为87.5%.患者动脉溶栓后与溶栓前NIHSS评分比较明显降低.时间窗大于5 h的前循环系统闭塞患者溶栓前后NIHSS评分无改善,与时间窗较短患者相比较,出院时mRS评分明显较高.5例颈内动脉闭塞患者溶栓前后NIHSS评分无改善,与9例大脑中动脉闭塞患者、2例基底动脉闭塞患者相比预后较差.4例患者溶栓后24h出现症状性颅内出血,3例为颈内动脉闭塞,1例死亡.1例溶栓后发生血管再闭,但因侧支循环血流丰富,最终临床预后仍较好.结论 对于时间窗超过3 h大脑中动脉和基底动脉闭塞急性缺血性卒中患者,动脉溶栓可使闭塞血管达到较高的再通率,短期内使临床神经功能恢复,改善临床结局.临床应用动脉溶栓时应注意个体化选择性治疗,评价其疗效需结合时间窗、血管闭塞部位、侧支循环、并发症等因素,避免出血等并发症.     

时间窗超过3h急性缺血性卒中患者动脉溶栓治疗观察

目的 评价时间窗超过3 h的急性缺血性卒中患者动脉溶栓治疗的疗效及影响因素.方法 选择法国南锡大学中心医院神经影像科自2008年1月至2009年1月收治的16例急性缺血性卒中患者(时间窗均达到或超过3 h,颈内动脉系统卒中时间窗不超过6 h,椎基底动脉系统卒中时间窗不超过24h.昏迷不超过6 h),行动脉内药物联合机械溶栓治疗,分析不同因素对疗效的影响.结果 7例患者闭塞血管达到完全再通,7例达到部分再通,另有2例闭塞血管未再通,再通率为87.5%.患者动脉溶栓后与溶栓前NIHSS评分比较明显降低.时间窗大于5 h的前循环系统闭塞患者溶栓前后NIHSS评分无改善,与时间窗较短患者相比较,出院时mRS评分明显较高.5例颈内动脉闭塞患者溶栓前后NIHSS评分无改善,与9例大脑中动脉闭塞患者、2例基底动脉闭塞患者相比预后较差.4例患者溶栓后24h出现症状性颅内出血,3例为颈内动脉闭塞,1例死亡.1例溶栓后发生血管再闭,但因侧支循环血流丰富,最终临床预后仍较好.结论 对于时间窗超过3 h大脑中动脉和基底动脉闭塞急性缺血性卒中患者,动脉溶栓可使闭塞血管达到较高的再通率,短期内使临床神经功能恢复,改善临床结局.临床应用动脉溶栓时应注意个体化选择性治疗,评价其疗效需结合时间窗、血管闭塞部位、侧支循环、并发症等因素,避免出血等并发症.     

Intra-arterial thrombolytic therapy improves outcome in patients with acute vertebrobasilar occlusive disease

In this retrospective analysis we report our treatment experience in 65 consecutive patients with clinical signs of severe brainstem ischemia with angiographically demonstrated thrombotic vertebrobasilar artery occlusions who received either local intra-arterial thrombolytic therapy (urokinase or streptokinase) (43 patients) or conventional therapy (antiplatelet agents or anticoagulants) (22 patients). We analyzed the data with respect to cerebral artery occlusion patterns, posttreatment arterial recanalization, and the clinical categories of favorable/unfavorable outcome and survival/death. In subgroup analyses, recanalization in patients who received thrombolytic therapy correlated significantly with clinical outcome; in 19 of 43 patients, recanalization was demonstrated angiographically, while in 24 patients the occlusion persisted. All patients without recanalization died, but 14 of the 19 patients displaying recanalization survived (p = 0.000007), 10 with a favorable clinical outcome. Only three of the 22 patients who received conventional therapy survived, all with a moderate clinical deficit. When we compared the treatment groups, highly significant differences in both outcome quality (p = 0.017) and survival (p = 0.0005) were found to depend on establishing recanalization. Our data support the concept that technically successful thrombolysis of vertebrobasilar artery occlusions is associated with beneficial clinical outcome.     

Long-term follow-up of patients after intraarterial thrombolytic therapy of acute vertebrobasilar artery occlusion

Local thrombolysis may reduce mortality after acute vertebrobasilar artery occlusion. We focused on variables affecting recanalization, outcome and long-term prognosis. Thirty-six patients with vertebrobasilar artery occlusion were treated with local intraarterial thrombolytic therapy. Four of the survivors were among the 16 patients without recanalization. Recanalization was associated with a higher survival rate. Top-of-the-basilar-type occlusions have the highest recanalization rate. The thrombolytic medication used did not influence the recanalization frequency. One patient died due to an intracerebral bleed after thrombolysis. There was no association between the time interval (greater or less than 6 h) between the onset of symptoms and therapy initiation and survival. Relapses during follow-up (mean follow-up 3.7 years) did not occur. MRI/MRA and ultrasound studies during follow-up showed unchanged results in these patients. All survivors at the time of follow-up lived at home.     

选择性动脉溶栓治疗急性大脑中动脉闭塞的体会

目的探讨选择性动脉溶栓治疗急性大脑中动脉闭塞的效果。方法对临床初诊急性大脑中动脉闭塞的患者,经全脑血管造影证实大脑中动脉闭塞并系责任血管后,取尿激酶50万IU稀释在50 ml生理盐水中,先在1 min内推注10万IU,再按1万IU/min泵入,每10 min造影一次。50 min泵完尿激酶,对再通者,停止溶栓;不全开通者再追加20万IU尿激酶;若血管还未开通或开通不理想,改用微导丝对血栓或栓子进行机械碎栓。结果采用选择性动脉溶栓与机械碎栓相结合的治疗方法,12例完全再通,8例部分再通,1例溶栓后再闭塞。2例血管完全开通后合并出血。16例患者临床症状得到改善,2例出现新的脑梗死灶。结论对于基层医院,采取选择性动脉溶栓和机械碎栓结合的方法救治急性大脑中动脉闭塞,疗效满意。     

亚急性、慢性椎-基底动脉闭塞的血管内再通治疗分析

目的探讨血管内支架再通术治疗亚急性、慢性椎-基底动脉闭塞的可行性、安全性及中远期疗效。方法回顾性分析2012年10月至2016年8月行血管内再通术治疗18例亚急性、慢性椎-基底动脉闭塞的的临床资料。结果 18例中,16例(88.9%)实现闭塞血管再通,闭塞血管远端中位TIMI血流分级由术前的0提高到2.4;术后6例症状改善,9例症状稳定,1例因颅内出血死亡。15例术后平均随访1年,其中11例改良Rankin量表评分较术前改善,4例没有明显改善;Malek评分1分12例,2分3例;DSA随访仅1例出现再狭窄(再狭窄程度大于50%),余未见明显血管内再狭窄。结论亚急性、慢性椎基-动脉闭塞腔内支架成形再通术在技术上是可行的,安全的,并且可以取得良好的中远期效果。     

Mechanical recanalization for acute ischemic stroke

Thrombolysis has become accepted as an effective treatment for acute ischemic stroke. However, two major problems remain: failure of recanalization and hemorrhagic complications. The combined use of mechanical recanalization techniques with thrombolytic agents occasionally may be required to improve recanalization rates and to reduce hemorrhagic complications. Percutaneous transluminal angioplasty (PTA), clot extraction utilizing retrieval devices, and clot fragmentation using energy of ultrasonic or laser vibrations and suction-creating saline jets are possible effective mechanical recanalization strategies, but mainly as a rescue therapy for patients with failed thrombolysis. However, for large artery occlusions, thrombolysis alone often results in failure of recanalization. In such cases, to minimize the total dose of thrombolytic agents and to prevent hemorrhagic complications, mechanical recanalization may be alternatively selected as the first choice of treatment. The safety and effectiveness of PTA for acute middle cerebral artery trunk occlusion has been reported using additional thrombolysis with low doses of thrombolytic agents for distal embolism by crushed fragments. Reduction of total doses of thrombolytic agents may decrease serious hemorrhagic complications, resulting in better clinical outcome.     

闭锁综合征临床与脑血管造影结果的对比研究

目的:研究椎一基底动脉系统缺血所致闭锁综合征的临床特点与全脑血管造影的情况。方法:对13例经MRI证实的双侧桥脑基底部梗塞的闭锁综合征患者行股动脉插管全脑血管造影术,观察脑供血障碍的情况,并给予静脉和动脉溶栓治疗。结果:13例患者死亡8例,存活5例,超早期静脉溶栓4例,效果不佳,早期动脉溶栓4例,2例闭塞的基底动脉再通,恢复较好。脑血管造影示双侧椎动脉起始部严重狭窄并扭曲2例,优势供血的椎动脉起始部严重狭窄1例,椎动脉V3段闭塞波及基底动脉下段2例,基底动脉起始段闭塞4例,基底动脉中段闭塞3例,基底动脉全程狭窄1例。结论:椎一基底动脉不同部位闭塞或严重狭窄可引起双侧桥脑基底部梗塞,表现为闭锁综合征,死亡率高,早期动脉溶栓有一定效果。     

Effects of microbubbles on transcranial Doppler ultrasound-assisted intracranial urokinase thrombolysis

Introduction

To evaluate the efficacy of microbubbles in transcranial Doppler ultrasound (TCD)-assisted urokinase thrombolysis.

Materials and Methods

Male New Zealand white rabbits (N = 32) were randomly divided into 2 groups, a urokinase group and a combined urokinase plus microbubble group. The middle cerebral artery (MCA) was occluded by injecting autologous blood clots through the carotid artery. In the urokinase plus microbubble group, sulfur hexafluoride (SonoVue) microbubbles were injected intravenously immediately after intravenous injection of urokinase. The 2 groups were monitored by TCD from before until 2 h after thrombolysis, and the hemodynamic changes and infarct size were recorded.

Results

The urokinase alone group had 1 case of complete recanalization and 4 cases of partial recanalization (recanalization rate, 31.3%). The urokinase plus microbubble group had 3 cases of complete recanalization and 6 cases of partial recanalization (recanalization rate, 56.3%). The average size of the infarction foci was 13.9% in the urokinase group and 9.1% in the urokinase plus microbubble group (P = 0.025). Pathological examination revealed no cerebral hemorrhage in either group.

Conclusions

The addition of microbubbles enhanced the effects of transcranial Doppler ultrasound-assisted urokinase thrombolysis.