A porcine deep vein thrombosis model for magnetic resonance-guided monitoring of different thrombectomy procedures

PURPOSE: To establish a porcine model of deep iliac vein thrombosis, which allows monitoring of thrombectomy and thrombolytic procedures by magnetic resonance imaging (MRI). MATERIALS AND METHODS: Deep iliac vein thrombosis was induced in 12 domestic swine using an occlusion-balloon catheter and subsequent injection of thrombin distal to the occluded vessel site. Thrombosis induction was successfully achieved in all animals after 1 hour as verified by MRI. In addition, x-ray fluoroscopy was performed for comparison. Subsequently, thrombectomy was performed using a Fogarty catheter, an Arrow-Trerotola percutaneous thrombolytic device as well as electrical discharge-induced shock waves. The latter procedure was carried out with and without additional administration of Actilyse. MRI and x-ray fluoroscopy were repeated to monitor therapy. RESULTS: After successful thrombosis induction within the deep iliac veins in all cases, thrombus material could be completely removed using the Fogarty catheter and the Arrow-Trerotola percutaneous thrombolytic device, whereas electrical discharge-induced shock wave failed to recanalize the occluded vessel even if additional Actilyse was administered. The actual burden of thrombotic material could be reliably visualized using MRI. CONCLUSIONS: A porcine model of deep iliac vein thrombosis model is presented, which permits reliable visualization of thrombotic material. This model might be a useful tool to compare different thrombectomy devices or to evaluate the effectiveness of new thrombolytic approaches.     

Percutaneous ilio-caval thrombectomy with the Amplatz device: preliminary results

The Amplatz Thrombectomy Device (ATD) is a percutaneous, rotational thrombectomy catheter, capable of recirculating and homogenizing the thrombus in order to obtain mechanical clot dissolution. The authors present their experience with mechanical thrombectomy with the ATD in eight cases of ilio-caval thrombosis. Under temporary caval filter protection, the ATD was introduced through the right transjugular approach (in one patient this was used in combination with the right femoral approach) and activated for a time ranging from 90 to 180 s. Complete clearing of thrombotic material in the treated venous segments was achieved in six cases (75 %), partial success was obtained in one case (12.5 %) and failure occurred in one patient (12.5 %). One patient developed a recurrence of venous iliac thrombosis 1 week after the procedure and postphlebitic syndrome 6 months after the first episode of deep venous thrombosis, and one patient died from acute myocardial infarction, unrelated to thrombectomy session, after 3 days. A negative clinical and radiological follow-up at 3, 6, 12 and 24 months was obtained in the remaining six patients. If a fresh free-floating ilio-caval clot must be removed immediately, the ATD can be effective under temporary filter protection. Received: 5 May 1998; Revision received: 8 June 1998; Accepted: 16 September 1998     

Prototype percutaneous thrombolytic device: preclinical testing in subacute inferior vena caval thrombosis in a pig model.

PURPOSE: To develop an animal model of subacute inferior vena caval (IVC) thrombosis and apply this model in evaluating the safety and efficacy of a prototype percutaneous thrombolytic device for restoring patency. MATERIALS AND METHODS: In 11 pigs, a stent with a ligature in the middle was placed in the IVC. Thrombin was injected to induce thrombosis. Hemostasis was achieved by using an occlusion balloon. The stent was ligated to prevent thrombus migration. Five to 8 days after thrombus induction, the ligature was broken and the stent fully deployed. In 10 animals, thrombectomy was performed by using the percutaneous thrombolytic device. A vena caval filter was inserted at the beginning of each declotting procedure. Thrombus removal percentage was estimated and pulmonary angiograms obtained to detect embolism before and after thrombectomy. The IVC was analyzed histologically. To determine thrombus composition, one animal was sacrificed without thrombectomy. Concerning procedural safety, failure of the stent delivery system, stent migration, and venous perforation due to balloon inflation and the stent placement or thrombectomy procedure were evaluated. RESULTS: Thrombus creation was successful in all animals. Fragmentation led to 75%--100% thrombus removal with flow restoration in all cases. There were no episodes of stent delivery failure, stent migration, or venous perforation. No significant pulmonary embolism was observed. In one case, a vessel dissection was identified at histologic examination. CONCLUSION: In this animal model of IVC thrombosis, the percutaneous thrombolytic device is effective and safe for clot removal.     

Percutaneous AngioJet thrombectomy in the management of extensive deep venous thrombosis

PURPOSE: This study was undertaken to evaluate the efficacy of a percutaneous mechanical thrombectomy (PMT) device for rapid thrombus removal following deep venous thrombosis (DVT). MATERIALS AND METHODS: Over a 37-month period, 17 patients (14 women; mean age, 41 y +/- 20) with extensive DVT were treated with initial attempts at PMT with use of the AngioJet rheolytic thrombectomy device. Sites of venous thrombosis included lower extremities in 14 patients and upper extremity and brachiocephalic veins in three. The etiology for venous thrombosis was malignancy in seven, idiopathic etiology in three, May-Thurner syndrome and immobilization in three each, and oral contraceptive use and hypercoagulable disorder in one each. The primary endpoint was venographic evidence of thrombus extraction. Perioperative complications, mortality, and recurrence-free survival were also evaluated. RESULTS: After PMT, four of 17 patients (24%) had venographic evidence of >90% thrombus removal, six of 17 (35%) had 50%-90% thrombus removal, and seven of 17 (41%) had <50% thrombus extraction. Adjunctive thrombolytic therapy was used in nine of 13 patients with <90% thrombus extraction by PMT; six patients (35%) had contraindications to pharmacologic thrombolytic therapy. An underlying lesion responsible for the occlusion was uncovered in 10 patients (59%). Significant improvement in clinical symptoms was seen in 14 of 17 patients (82%). No complications were noted directly relating to the use of the AngioJet thrombectomy catheter. None of the patients were lost to follow-up during a mean of 8.9 months +/- 5.3 (range, 2-21 months). At 4 and 11 months, recurrence-free survival rates were 81.6% and 51.8%, respectively. CONCLUSION: PMT with adjunctive thrombolytic therapy is a minimally invasive, low-risk therapeutic option in patients with extensive DVT, associated with clinical benefits including thrombus removal, patency, and relief of symptoms.     

机械性血栓切除和开通治疗慢性血管内血栓

目的　探索机械性血栓切除和开通治疗慢性血管内血栓的可行性 ,初步分析疗效并讨论适应证、禁忌证。方法　本组 2 3例患者血管内血栓均行MRA、血管超声及血管造影证实。其中 12例患有慢性心力衰竭和 (或 )血管性疾病 ,11例为重度糖尿病 ,血栓位于髂动脉 10例 ,股动脉 2例 ,动脉3例 ,髂静脉 7例 ,门静脉 1例。血栓长度为 3～ 8cm ,血栓直径为 5～ 10mm。 7例髂静脉血栓患者行血栓物理性治疗前先行放置下腔静脉滤器。射频消融 (ATD)治疗 9例 (7例静脉 ) ,经皮电动网篮 (PTD) 2例 (门静脉 ) ,流变溶栓 (OASIS) 3例 (动脉 2例 ,静脉 1例 ) ,内支架直接开通 9例 (均为动脉 )。所有患者在血栓治疗过程中采用 5 0万U的尿激酶通过导管内直接进行溶栓。物理性血栓切除后如造影证实血管狭窄者于狭窄部行血管内支架放置。术后治疗包括内科溶栓、肝素抗凝和改善微循环等药物治疗。随访包括血管超声、CT血管重建随访及临床症状随访。结果　 12例 (85 .7% )成功进行了物理性血栓切除。 1例门脉血栓者失败 ,1例股动脉血栓患者同时进行ATD和OASIS治疗。 2 1例 (91.3% )患者症状明显改善和消失 ,包括缺血、肿胀、活动受限。血管超声随访血管通畅率 :10 0 % (3个月 ) ,85 .4 % (6个月 ) ,73.2 % (12个月 ) ;同时 3个月、     

深静脉血栓的血管内溶栓治疗

通过对深静脉血栓的血管内溶栓治疗分析，提供一种有效的治疗静脉血栓的新方法。本组７例，左髂总静脉血栓４例，左髂外静脉２例，右髂外静脉１例，７例均先插管逆，顺行静脉造影确定血栓长度及病变程度。     

Stent Placement on Fresh Venous Thrombosis

Purpose: To report on the efficacy of fixing fresh venous thrombus to the venous wall by stent placement. Methods: Seven patients underwent stenting to treat acute venous thrombosis. In two patients, the hemodialysis fistula was thrombosed with the thrombus extending into the brachial veins. In three patients, the hemodialysis fistula was patent but massive swelling of the ipsilateral arm was caused by proximal venous thrombosis. Two patients presented with iliac venous thrombosis within stented pelvic veins. Stent placement was preceded by other mechanical thrombectomy methods in all cases. Results: Attachment of thrombus to the venous wall was successful in all cases treated. Acute rethrombosis did not occur. Follow-up patency in dialysis patients was 7.2 ± 2.1 months. One patient had rethrombosis of the dialysis graft 3 months after primary treatment. Three patients developed restenosis within a mean period of 7.7 months. One shunt remained patent for 10 months with no event of reobstruction during follow-up. In both patients with iliac stent placement, the vein remained patent over a follow-up period of 8 and 12 months respectively. Conclusion: Stenting fresh venous thrombus can achieve immediate venous patency. It may be used as an alternative approach when all other percutaneous methods fail. Frequent restenosis within stented veins limits its use to very selected cases. Received: 0/00/00/Accepted: 0/00/00     

经动脉序贯静脉置管溶栓治疗急性混合型下肢深静脉血栓26例的初步临床疗效观察

目的评价经动脉序贯静脉置管溶栓治疗急性混合型下肢深静脉血栓（lower extremity deep vein thrombosis,LEDVT）的安全性和有效性。 方法回顾性分析26例急性混合型LEDVT患者的临床资料。患者术前置入下腔静脉滤器,穿刺左侧肱动脉于患侧髂动脉置管溶栓,2～3 d后复查造影并穿刺患侧腘静脉行球囊扩张（percutaneous transluminal angioplasty,PTA）+手动抽栓（percutaneous mechanical thrombectomy,PMT）+置管溶栓（catheter directed thrombolysis,CDT）。观察血栓清除情况、患侧下肢周径变化情况及溶栓并发症等。 结果26例患者经动脉置管溶栓后24例（92.31%）腘静脉及膝下段深静脉血栓大部分溶解;之后行PTA+PMT+CDT操作1次者17例（65.39%）,操作2次者7例（26.92%）,操作3次后置入髂静脉支架者2例（7.69%）。血栓清除率Ⅲ级者22例（84.62%）,Ⅱ级者2例（7.69%）,I级者2例（7.69%）。治疗前膝上周径与健侧差值为（5.02±2.29）cm,治疗后差值为（0.74±0.18）cm,两者比较具有显著的统计学差异（t=7.601,P<0.001）。26例溶栓治疗无严重并发症。 结论经髂动脉置管溶栓序贯腘静脉PTA+PMT+CDT对于急性混合型LEDVT治疗安全有效。     

经皮导管抽吸去栓术治疗急性下肢深静脉血栓形成

目的：探讨经皮导管抽吸去栓术在急性下肢深静脉血栓形成（deep venous thrombosis,DVT）综合介入治疗术中的临床应用价值。方法：34例左侧急性下肢DVT,均经右侧股静脉穿刺置入下腔静脉滤器,随后经左侧股静脉或胭静脉穿刺插管,行导管抽吸去栓,最后对左侧髂总静脉进行球囊血管成形术。结果：31例血栓一次性清除,3例部分清除;所有病例均存在左髂静脉受压综合征;左下肢水肿完全消退30例,部分消退4例;未出现肺栓塞或其它并发症,随访6～52个月,临床治愈者元复发。结论：经皮导管抽吸去栓术治疗急性下肢DVT是一种快捷、有效的方法,值得临床推广。     

Clot-trapper device for transjugular thrombectomy from the inferior vena cava

The clot-trapper device for transjugular thrombectomy was used in 10 dogs with acute thrombosis and two dogs with chronic thrombosis. In eight of these animals, the clots were trapped with the clot-trapper device, then a mechanical thrombectomy device was used to destroy the clots. In 10 animals, including eight with in vitro thrombi and two with in situ thrombi, thrombi were efficiently trapped with the clot-trapper device. In two animals, pulmonary embolism occurred because of a discrepancy between the diameter of the inferior vena cava and the diameter of the bag opening. After increasing the size of the loop to match the diameter of the inferior vena cava, trapping of all thrombi was possible in both experiments (acute and chronic thrombosis). The clot-trapper device, in conjunction with an embolectomy balloon catheter and/or a mechanical thrombectomy device, facilitates the removal of thrombi from the inferior vena cava and iliac veins.     

Does umbilical vein catheterization lead to portal venous thrombosis? Prospective US evaluation in 100 neonates

PURPOSE: To establish, by means of serial ultrasonography (US), the incidence and natural history of neonatal portal venous thrombosis associated with catheterization of the umbilical vein and to evaluate the potential risk factors predisposing patients to thrombus formation. MATERIALS AND METHODS: Neonates who had undergone umbilical vein catheterization were studied. US was performed at 2-7-day intervals, before and after the removal of the catheter, until clot resolution or hospital discharge. The presence of portal venous thrombosis and temporal evolution were noted, and various risk factors were analyzed. RESULTS: US demonstrated clinically silent portal venous thrombosis in 43 (43%) of 100 neonates. Follow-up US revealed complete or partial resolution in 20 (56%) of 36 babies. A significant (P =.024) correlation was found between the initial size of the thrombi and spontaneous clot resolution. Statistically significant risk factors were catheterization for more than 6 days (P =.001) and transfusion (P =.019). CONCLUSION: Portal venous thrombosis is frequently associated with the placement of an umbilical venous catheter, and spontaneous resolution is expected in many cases. The duration of catheter placement should be minimized, and US monitoring is recommended as a guide to catheter removal.     

Mechanical Thrombectomy of Iliac Vein Thrombosis in a Pig Model Using the Rotarex and Aspirex Catheters

Purpose

To investigate the efficacy and safety of mechanical thrombectomy for iliac vein thrombosis using Rotarex and Aspirex catheters in a pig model.

Materials and Methods

Iliac vein thrombosis was induced in six pigs by means of an occlusion-balloon catheter and thrombin injection. The presence of thrombi was verified by digital subtraction angiography (DSA) and computed tomography (CT). Thrombectomy was performed using 6F and 8F Rotarex and 6F, 8F, and 10F Aspirex catheters (Straub Medical AG, Wangs, Switzerland). After intervention, DSA and CT were repeated to evaluate the efficacy of mechanical thrombectomy and to exclude local complications. In addition, pulmonary CT was performed to rule out pulmonary embolism. Finally, all pigs were killed, and iliac veins were dissected to perform macroscopic and histological examination.

Results

Thrombus induction was successfully achieved in all animals as verified by DSA and CT. Subsequent thrombectomy lead to incomplete recanalization of the iliac veins with residual thrombi in all cases. However, the use of the 6F and 8F Rotarex catheters caused vessel perforation and retroperitoneal hemorrhage in all cases. Application of the Aspirex device caused one small transmural perforation in a vessel treated with a 10F Aspirex catheter, and this was only seen microscopically. Pulmonary embolism was detected in one animal treated with the Rotarex catheters, whereas no pulmonary emboli were seen in animals treated with the Aspirex catheters.

Conclusion

The Aspirex catheter allowed subtotal and safe recanalization of iliac vein thrombosis. In contrast, the use of the Rotarex catheter caused macroscopically obvious vessel perforations in all cases.     

经腘静脉顺行穿刺治疗下肢静脉血栓的探讨

目的：探讨经腘静脉顺行穿刺治疗下肢静脉血栓的可行性及优越性。方法：下肢静脉血栓患者19例，经对侧股静脉放置下腔静脉滤器后，使用骨科止血带加压成功穿刺腘静脉，15例顺行插管抽血栓，4例使用Amplatz血栓清除器（ATD）。结果：19例均获成功，栓塞血管复通达100％。临床症状消失，无症状性复发。结论：下肢静脉血栓中使用骨科止血带后可有效地提高顺行穿刺腘静脉成功率，是下肢静脉溶栓治疗的有效方法。     

Abdominal venous system: assessment using MR

Twenty-five patients with known or suspected evidence of venous disease based on results of computed tomography, angiography, or ultrasound were imaged with magnetic resonance (MR) to determine the MR characterization of venous abnormalities. MR findings were proved by laparotomy or autopsy in 18 of 25 cases. In seven of 25 patients in whom only biopsy was performed, the MR findings were correlated with findings from other radiologic tests. On MR, the inferior vena cava (IVC), portal vein, and their major tributaries were seen in all but two cases. In those two, identification of collaterals led to the correct diagnosis of splenic vein thrombosis in one case and left renal vein thrombosis in another. MR imaging helped identify intraluminal thrombi in the IVC (12 of 12 cases), portal vein (two of two cases), renal veins (seven of seven cases), superior mesenteric vein (one case), and iliac veins (seven of seven cases). Intraluminal signal intensity secondary to slow blood flow seen in five patients was always differentiated from the thrombus. MR imaging helped identify correctly the nature of the thrombus in 11 of 16 patients. In five patients, the differentiation between tumor thrombus and blood clot thrombus was not possible. Involvement of the IVC wall by tumor was seen in four cases. MR imaging also accurately depicted slow flow in obstructed or constricted veins; encasement, compression, or displacement of veins without intraluminal occlusions; and the presence of venous collaterals. The MR imaging evaluation of venous abnormalities is accurate, easily performed, and will probably become an important application.     

髂静脉受压综合征及继发血栓形成的介入治疗

目的 探讨髂静脉受压综合征(ICS)及继发深静脉血栓形成(DVT)的介入治疗效果.方法 回顾性分析125例经DSA明确诊断为ICS及继发DVT的患者资料,其中单纯ICS患者39例,ICS继发DVT患者86例.对不伴有新鲜血栓的髂静脉受压及髂静脉狭窄、闭塞的患者行经皮腔内血管成形术和自膨支架置入术,对伴有髂、股静脉新鲜血栓的髂静脉受压患者在置入下腔静脉滤器后行经导管血栓抽吸、机械性血栓消融、腔内血管成形、支架置入术及经导管溶栓.采用卡方检验对单纯ICS患者及ICS继发DVT患者出院时和出院后6个月的治疗有效率和优良率进行比较.结果 39例单纯ICS患者中,38例实施了腔内成形和支架置入术;86例继发有DVT的ICS中,83例实施了各种腔内介入治疗.ICS患者及ICS继发DVT患者出院时的治疗有效率分别为97.4%(38/39)和96.5%(83/86),出院后6个月分别为96.3%(26/27)和90.2%(46/51),差异均无统计学意义(X2值分别为0.000和0.266,P值均>0.05);ICS患者及ICS继发DVT患者出院时的治疗优良率分别为94.9%(37/39)和79.1%(68/86),出院后6个月分别为92.6%(25/27)和68.6%(35/51),差异均有统计学意义(X2值分别为3.879和4.441,P值均<0.05).结论 介入治疗ICS及继发DVT安全、有效,并且应尽早发现和处理ICS.     

Ovine Iliac Vein Model for Endovascular Thrombectomy of Acute Deep Venous Thrombosis

An ovine iliac vein thrombosis model was devised to test a wall-contacting rotational thrombectomy device. Thrombosis was successfully induced in 9 sheep with an average clot length of 31 mm ± 12 and >60% vessel occlusion on angiography. The thrombus was subsequently removed, maintaining normal intraoperative pulmonary arterial pressure (5.9 mm Hg ± 3.6) and complete distal reperfusion after thrombectomy. Additionally, the sheep were without signs of vascular trauma or embolic complications on gross necropsy and histopathologic analysis. The findings from this study support the use of an ovine iliac deep vein thrombosis model for testing of a lower extremity thrombectomy device.     

Saline-jet aspiration thrombectomy catheter. Clinical results in patients with venous thrombosis

PURPOSE: To evaluate hydraulic thrombectomy using a saline-jet aspiration thrombectomy catheter in the treatment of venous thrombosis. MATERIAL AND METHODS: Ten patients underwent 12 hydraulic thrombectomy procedures using 2.7 or 4.0 mm catheters. The site of the thrombus was either central, peripheral or in portal veins. The age of the thrombi was between 2 and 60 days (mean 19.7 days). The efficacy of hydraulic thrombectomy was evaluated based on the aspirated thrombus ratio (ATR), i.e. the volume of the thrombus aspirated divided by the volume of the thrombus before thrombectomy. ATR was estimated by comparing the angiograms of the lesion before and after thrombectomy. RESULTS: Soft thrombi were usually rapidly removed. ATR was >2/3 in 3, 2/3-1/3 in 2, 1/3-0 in 4, and 0 in 1 patient. The activation time of the injector was 23-224 s (mean 102 s) and the volume of aspirated blood was 30-680 ml (mean 250 ml). Compensatory infusion of saline was performed for blood loss, and 400 ml of packed red blood cells was transfused in 1 patient. No complications of the hydraulic thrombectomy were observed. Thrombolysis or additional treatment were performed in 9 patients. CONCLUSION: Hydraulic thrombectomy using this catheter can contribute to the treatment of venous thrombosis.     

Deep venous thrombosis in pregnancy: noninvasive diagnosis

In pregnant patients, venous thrombosis usually affects the left-side iliofemoral deep vein. Vascular ultrasound (US) offers distinct advantages in confirming the clinical suspicion of disease or suggesting the need for further tests. The authors encountered three consecutive cases of antepartum proximal vein thrombosis during a 6-month period (0.6 case per 1,000 deliveries). Lack of venous flow accentuation and lack of diameter change at the common femoral vein during the Valsalva maneuver are indications for iliac venography and suggest the diagnosis of iliac vein thrombosis. In distal iliac and proximal femoral vein thrombosis, noncompressibility of the vein and the presence of echogenic material within are indicative of acute thrombus.     

Selective venous thrombolysis with the nipple-balloon catheter: comparative evaluation in vivo.

PURPOSE: To compare in an animal model of deep vein thrombosis, an intramural drug delivery catheter, the nipple-balloon catheter, with an occlusion balloon-infusion guide wire system. MATERIALS AND METHODS: Ten juvenile pigs were used for the study. Deep vein thrombosis was induced in both hind limbs by using a previously described technique. Heparin was administered 30 minutes later (2,500 IU intravenously) and bilateral thrombolysis was attempted with use of 8 mg of alteplase as a 0.25 mg/mL solution containing heparin 50 IU/mL (n = 10) and sodium/meglumine ioxaglate 40 mgI2/mL (n = 5). In one limb, the external iliac vein was endoluminally occluded, and 0.8 mL of alteplase was administered every 3 minutes through a multisideport infusion wire placed coaxially through the balloon catheter. On the other side, a nipple-balloon catheter was used: alteplase was injected as two 0.4-mL aliquots every 3 minutes in overlapping segments of the vessel. Blood samples were taken at predetermined intervals to determine the partial thromboplastin time and plasma fibrinogen concentration. At autopsy, the thrombus mass in the iliofemoral veins was measured, and the extent of residual thrombosis in the venous tributaries was graded at four sites. The heart and the lungs were also examined for thromboemboli (n = 5). Venous specimens were then subjected to X-ray fluorescence spectrometry to determine iodine content (n = 5). RESULTS: Bilateral thrombolysis could be successfully completed in all animals. No procedural problem associated with the use of the nipple-balloon catheter was encountered. The mass of residual thrombus in the axial veins was significantly lower in this group (P = .005). The drug delivery system used did not appreciably influence thrombolysis in the tributaries. Signs of macroscopic damage to the veins were not observed in any animal. None of the venous specimens had detectable levels of iodine. Small thromboemboli were found in the pulmonary circulation in three of five animals. Fibrinogen levels did not decrease during the procedure. CONCLUSIONS: The significantly lower residual thrombus burden associated with use of the nipple-balloon catheter suggests that the device may have the potential to be an effective delivery system for selective thrombolysis in veins.     

Lower extremity venous thrombolysis with adjunctive mechanical thrombectomy

PURPOSE: To evaluate the use of adjunctive mechanical thrombectomy (MT) with pharmacologic catheter-directed lower extremity venous thrombolysis. MATERIALS AND METHODS: Catheter-directed thrombolysis with adjunctive MT was used to treat 28 symptomatic limbs in 20 patients (22 procedures) with lower extremity deep vein thrombosis (DVT) between August 1997 and July 2001. Procedural success, major bleeding, thrombolytic infusion time, and total thrombolytic agent dose were recorded. RESULTS: Procedural success was achieved in 23 of 28 limbs (82%). Fifteen patients (18 limbs) received iliac vein stents. Major bleeding was observed after three of 22 procedures (14%) and resulted in transfusion in two patients and endometrial ablation in the third patient. Mean per-limb infusion time was 16.8 hours +/- 12.8. Mean per-limb total doses were lower than those reported in published studies of DVT thrombolysis: 2.67 million U +/- 1.60 urokinase, 18.4 mg +/- 10.7 tissue plasminogen activator, and 13.8 U +/- 6.9 reteplase. Venographic analysis demonstrated minimal thrombus removal (26.0% +/- 24.1) when using MT alone, compared with substantial thrombus removal (62.0% +/- 24.9) when using MT after pharmacologic thrombolytic agents had been administered (P =.006). CONCLUSION: The use of adjunctive MT to augment pharmacologic catheter-directed DVT thrombolysis provides comparable procedural success and may reduce the required thrombolytic dose and infusion duration.