BACKGROUND: To study the long-term patency of thrombosed prosthetic vascular access grafts treated with percutaneous mechanical thrombectomy (PMT) followed by aggressive surveillance and monitoring and repeated endovascular interventions. STUDY DESIGN: Two hundred seven vascular access grafts presented with first-time thrombosis were treated with PMT using the AngioJet device (n=185) or the Arrow-Trerotola percutaneous thrombolytic device (n=22) followed by angioplasty (+/- stenting) of the anatomical lesion responsible for the thrombotic event. Clinical success was considered at least one successful subsequent hemodialysis session. Graft surveillance/monitoring included clinical and hemodialysis parameters to detect a failing or thrombosed graft. RESULTS: PMT was technically successful in 202 cases (97.6%) and clinically successful in 193 cases (93.2%). During follow-up, 149 got thrombosed and either abandoned (n=33) or underwent at least once repeat thrombectomy (n=116); finally 100 grafts were abandoned (n=90), ligated (n=5) or removed (n=5). Endovascular management (0.54 procedures per 100 graft-days, thrombectomy, n=307 sessions and angioplasty, n=162 sessions) increased significantly functional assisted-primary patency rates from 29% and 14% at 1 and 2 years to a secondary patency of 62% and 47%, respectively. Secondary patency was worse in loop grafts (P=.02) and intermediate graft thrombosis (occurred between 31-182 days after graft placement, P<.001) and better when renal failure was due to hypertension or diabetes (compared to other or cryptogenic causes, P=.048) or isolated angioplasty for graft dysfunction during follow-up had been performed (P<.001). Multivariate analysis identified intermediate graft thrombosis and isolated angioplasty as independent predictors of secondary patency (P<.001, relative risk 2.77 and P<.001, relative risk 0.28, respectively). CONCLUSIONS: PMT is a highly successful procedure with acceptable long-term secondary patency results, provided that aggressive endovascular management of subsequent thrombotic or dysfunction episode is performed. Further research to identify the causes of intermediate graft thrombosis is justified.

Until recently, acute arterial or venous thromboses were routinely managed with surgical intervention. With the development of effective thrombolytic pharmacologic agents and improved modes of delivery of these agents to the target site, surgery is no longer the only option. Greater understanding and knowledge about the finely orchestrated, counterbalanced processes of coagulation and fibrinolysis/thrombolysis have enabled development of agents and strategies for pharmacologic restoration of vascular patency while reducing or eliminating the need for surgery. An evidence-based rationale now exists for the use of thrombolysis in acute limb ischemia, deep venous thrombosis, stroke, and arteriovenous vascular access thromboses. Thrombolytic agents are valuable ancillary agents that allow a less invasive solution to a variety of thrombotic vascular conditions. Strategies that combine thrombolytic agents with endovascular techniques provide precise delivery of these drugs to the target thrombus. A more widespread adoption of this strategy has been limited primarily owing to problems with the currently available pharmacologic agents. The future of thrombolysis therapy is discussed in terms of data obtained from ongoing and recently completed clinical trials. Efforts to develop and study new thrombolytic agents that act directly on the thrombus without activation of intermediary biochemical steps will provide the next major step forward, as well as the rational basis for expansion of currently accepted indications for the treatment of acute arterial and venous thromboses.

Purpose: To study the outcome of rheolytic thrombectomy for hemodialysis access occlusion. Methods: A prospective study was conducted of 187 patients (88 men; median age 63 years, range 21-89) with end-stage renal disease treated with the AngioJet rheolytic thrombectomy catheter followed by angioplasty (+/- stenting) of the culprit lesions in 285 episodes of arteriovenous graft (n = 261) or fistula (n = 24) thrombosis. Clinical success was defined as at least one successful subsequent hemodialysis session. Graft monitoring and surveillance included clinical and hemodialysis parameters, respectively, to detect a failing/failed access. Results: Rheolytic thrombectomy had a technical (immediate) success rate of 98.2% and a clinical success rate of 95.1%. Technical and clinical success for patients presenting within 2 days of the thrombosis was 99.6% and 96.6%, respectively, compared to 91.8%(p = 0.003, odds ratio 20.8) and 87.8%(p = 0.019, odds ratio 4) for later presentation. The number of stenoses that was managed (median, interquartile range) was significantly higher in grafts (4, 3-4) compared to fistulae (2, 2-3; p<0.001) and in accesses that had been treated for dysfunction or thrombosis in the past (4, 3-4) compared to accesses that had not (3, 3-4; p = 0.07). During follow-up, 95 (36.6%) accesses had no further thrombotic events, 23 (9%) accesses became dysfunctional and were treated with endovascular techniques, 137 (52.3%) developed recurrent thrombosis for which rheolytic thrombectomy was attempted, and 30 (11.5%) were abandoned or removed for infection. Functional assisted primary patency at 1, 6, 12, and 18 months was 72.4%, 45.1%, 30.3%, and 22.4%, respectively. Reintervention and venous outflow stenosis were associated with better and worse outcomes, respectively; multivariate analysis identified patient age, central vein stenosis, and stenting as additional independent predictors of improved patency. Conclusion: Rheolytic thrombectomy is a highly successful procedure, with acceptable long-term assisted primary patency. Early referral for thrombectomy should be encouraged.

Purpose: To retrospectively review the complications reported during percutaneous thrombectomy procedures performed on polytetrafluoroethylene hemodialysis grafts. Materials and Methods: A retrospective review revealed that 935 percutaneous thrombectomy procedures were performed at our institution between January 1993 and June 2001. The type and number of procedures include: Arrow PTD (527), pulse-spray with urokinase (240), Amplatz Thrombectomy Device (96), AngioJet (17), Oasis (15), Hydrolyser (10), Endovac (7), Lyse and Wait (7), Thrombex (6), Cragg brush (6), Castaneda brush (4). Complications were reported to have occurred in 31 patients. The radiology reports and medical records of these patients were reviewed. Results: The overall complication rate was 3.3%. The type and number of complications included: rupture of a vein during angioplasty (13), severe cardiopulmonary distress (4), arterial emboli (4), rigors related to urokinase (3), minor bleeding (2), hypoxia with chest pain (2), other assorted complications (3). There was one death resulting from a fall from the angiography table immediately following the procedure. There were 12 minor complications, requiring minimal treatment, and 19 major complications that altered the course of the procedure or treatment of the patient. Conclusion: The most common complication was angioplasty-induced rupture of the vein or graft. The most severe complications occurred immediately following dislodgement of the arterial plug and were likely due to acute pulmonary embolization.

PURPOSE: Endovascular removal of intravascular thrombus using the AngioJet rheolytic thrombectomy (RT) system has been shown to be clinically effective. This system also permits the concomitant infusion of thrombolytic agent followed by thrombectomy, thus creating a novel strategy known as pharmacomechanical thrombectomy (PMT). Although these interventions have gained wide clinical application, little is known regarding the vessel wall response following thrombectomy therapy. The aims of this study were to assess the effect of thrombectomy interventions on endothelial function in a porcine model of deep venous thrombosis (DVT) and to evaluate the effect of nitric oxide (NO) precursor L-arginine on endothelial function following thrombectomy therapy. METHODS: Deep vein thrombosis was created in bilateral iliac veins by deploying a self-expanding stent-graft incorporating an intraluminal stenosis from a groin approach. Five pigs underwent sham operation. Following 14 days of DVT, animals were randomized to three groups: the first group received RT treatment (RT group, n = 5); the second group received pharmacomechanical thrombectomy (PMT) with tissue plasminogen activator (alteplase 10 mg; PMT group, n = 5); and the third group received PMT with tPA plus intravenous L-arginine (20 mmol/l)(arginine group, n = 5). Iliac vein patency was evaluated by venography and intravascular ultrasound at 1 week. Nitric oxide level was determined by a chemiluminescent assay of the nitrite/nitrate metabolites (NO(x)). Thrombogenicity was evaluated by radiolabeled platelet and fibrin deposition. Veins were harvested and evaluated with light microscopy and scanning electron microscopy (SEM). Endothelial function was evaluated using organ chamber analysis. RESULTS: The luminal areas in the sham, RT, PMT, and arginine groups were 34 +/- 10 mm(2), 21 +/- 13 mm(2), 35 +/- 18 mm(2), and 37 +/- 16 mm(2), respectively. All iliac veins remained patent at 2 weeks. No difference in endothelial cell structure was observed between the three treatment groups by means of light microscopic or SEM examination. A decrease in platelet deposition occurred in the arginine group compared to the RT and PMT groups (P < 0.05). The arginine group also showed a greater endothelium-dependent relaxation compared to the RT or PMT groups in response to A23187, bradykinin, and ADP (P < 0.05). Local NO(x) level was higher in the arginine group than in the RT or PMT group (2.6 +/- 0.6 mumol/l versus 0.3 +/- 0.1 mumol/l and 0.3 +/- 0.2 mumol/l; P < 0.01). CONCLUSIONS: AngioJet RT and PMT interventions resulted in similar attenuated endothelium-dependent vasoreactivity and morphologic effect. L-Arginine supplementation preserves endothelial vasoreactivity and reduces platelet deposition following PMT in iliac DVT. Additionally, L-arginine enhances NO production at sites of venous thrombosis. The NO precursor L-arginine may have a therapeutic potential in preserving endothelial function following mechanical thrombectomy.

PURPOSE: The present study sought to evaluate the performance of the Arrow-Trerotola Percutaneous Thrombolytic Device (PTD) in the treatment of native fistula thrombosis in a U. S. hemodialysis population. Specifically, the technical success, clinical success, complication rate and type, primary and secondary patency rates, effect of adjunctive thrombolytic therapy, and any variables that affected outcomes of procedures in which this device was used were analyzed. MATERIALS AND METHODS: Forty-two patients with 44 thrombosed native fistulas (17 radiocephalic, 10 brachiocephalic, 10 transposed or superficialized, five graft/fistula hybrids, and two leg fistulas) were treated with 62 mechanical thrombolysis procedures with use of the PTD. All patients had large clot burden. The device type was recorded in 43 procedures: standard (n = 21), over-the-wire (OTW; n = 19), or both (n = 3). No device was used in two cases because of inability to cross the anastomosis. Adjunctive therapies (n = 18) included the use of tissue plasminogen activator (tPA; n = 16) and deployment of the AngioJet device with (n = 1) or without tPA (n = 1). Stents were inserted in four procedures. Outcome variables included technical and clinical success, complications, and primary and secondary patency. Cox proportional-hazards regression and Kaplan-Meier analyses were performed. RESULTS: The technical success rate was 87%(54 of 62) and the clinical success rate was 79%(49 of 62). Percutaneous transluminal angioplasty was performed in all but two procedures. Complications occurred in 13% of procedures (n = 8); three resulted in technical failure. The primary patency rates were 38% at 6 months and 18% at 12 months; secondary patency rates were 74% and 69%, respectively. Outcomes were not affected by adjunctive techniques, fistula type, age of fistula, device type (ie, OTW vs standard), or patient sex. Secondary patency was superior when no residual clot or stenosis was present (P =.003). CONCLUSIONS: The PTD is effective for percutaneous treatment of thrombosed hemodialysis fistulas, with good short- and long-term outcomes in a U.S. population. Within the limitations of a retrospective study with a small sample size, use of an adjunctive thrombolytic agent did not appear to improve results compared with the use of the device alone.

The purpose of this study was to evaluate the efficacy and safety of a new hydrodynamic percutaneous thrombectomy catheter in the treatment of thrombosed hemodialysis fistulas and grafts. Twenty-two patients (median age: 47 years; range: 31-79 years) underwent mechanical thrombectomy for thrombosed hemodialysis fistulas or polytetrafluoroethylene (PTFE) grafts. In all cases, an Oasis hydrodynamic catheter was used. Five patients had native fistulas and 17 had PTFE grafts. Six patients required repeat procedures. All patients with native fistulas and 15 of the 17 with PTFE grafts also underwent angioplasty of the venous limb following the thrombectomy. Major outcome measures included technical success, clinical success, primary and secondary patency, and complication rates. Twenty-eight procedures were performed in total. The technical success rate was 100% and 90% and clinical success was 86% and 76% for native fistulas and grafts, respectively. The primary patency at 6 months was 50% and 59% for fistulas and grafts, respectively, and the secondary patency at 6 months was 75% and 70% for fistulas and grafts, respectively. Two patients died of unrelated causes during the follow-up period. The Oasis catheter is an effective mechanical device for the percutaneous treatment of thrombosed hemodialysis access. Our initial success rate showed that the technique is safe in the treatment of both native fistulas and grafts.

We report the final results of the trial comparing the Amplatz thrombectomy device (ATD) with surgical thromboembolectomy (ST) to declot thrombosed dialysis access grafts (DAG). The study population consisted of 174 DAG, 109 of which were randomized to mechanical thrombectomy using the ATD and 65 of which were randomized to conventional surgical thromboembolectomy. Forty grafts were re-enrolled in the trial when they failed beyond the 90 days follow-up after the initial treatment. Thirty-one were re-enrolled for mechanical thrombectomy and nine were re-enrolled for surgical thrombectomy, resulting in a total of 140 ATD procedures and 74 surgical thromboembolectomy. Immediate thrombectomy success was defined as greater than 90% thrombus removal followed by the ability to dialyze after treatment, and analysis of long term success based on graft patency at 30 and 90 days, with successful dialysis. Immediate thrombectomy success with the ATD procedure was achieved in 79.2% and with ST in 73.4%. Patency of the graft, with successful dialysis, at 30 days with the ATD procedure was 79.2% and with ST was 73.4%. Patency of the graft, with successful dialysis, at 90 days with the ATD procedure was 75.2% and with ST was 67.8%. The data collected in this study provided a prospective comparison of mechanical thrombectomy with the ATD and ST performance in thrombosed DAG. The results of the performance of both methods were comparable. No statistically significant differences were seen.

BACKGROUND: The purpose of this report was to analyze the results obtained from a group of interventional nephrologists working in multiple centers performing basic procedures that are used routinely in the management of vascular access problems, with an effort toward establishing standards for evaluating success, complication rates, and acceptable times for procedure duration and fluoroscopy. METHODS: Data on six basic procedures were analyzed-angioplasty of arteriovenous fistulas (AVF-PTA), angioplasty of synthetic grafts (graft-PTA), thrombectomy of arteriovenous fistulas (AVF declot), thrombectomy of synthetic grafts (graft declot), placement of tunneled dialysis catheters (TDC placement), and tunneled dialysis catheter exchange (TDC exchange). These data were examined both as a group and by individual physician operator. RESULTS. A total of 14,067 cases were performed under the six categories of procedure that were the subject of this report; 13,503 cases (96.18%) were successful. The overall complication rate for the combined group of procedures was 3.54%, with 3.26% falling within the minor category and 0.28% within the major. The number of cases performed in each individual category with success rates for each were as follows: TDC placement-1765 cases, 98.24% successful; TDC exchange-2262 cases, 98.36% successful, AVF-PTA-1561 cases, 96.58% successful; graft-PTA-3560 cases, 98.06% successful; AVF declot-228 cases, 78.10% successful; graft declot-4671 cases, 93.08% successful. CONCLUSION: This study demonstrates that appropriately trained interventional nephrologists can perform these basic procedures in both a safe and effective manner.

BACKGROUND: Access failure in hemodialysis patients is commonly encountered by vascular surgeons. Researchers have reported various solutions for dealing with clotted grafts, including thrombectomy, thrombolysis, interposition grafting, angioplasty, or a combination of these methods. Surgical thrombectomy has been the standard procedure for dealing with thrombosed hemodialysis grafts in the cardiovascular department of Chang Gung Memorial Hospital. However, to correct associated stenotic lesions and improve the results of surgery, intraoperative balloon angioplasty has been applied in consecutive cases of dialysis graft failure since July 2001. METHODS: Initial experience with 13 consecutive intraoperative balloon angioplasties performed during a 2-month period was reviewed. Noncompliant high-pressure balloons were used for the procedures. Age, gender, graft age, and initial outcome were reviewed and analyzed. RESULTS: A success rate of 100% was achieved in the group that underwent thrombectomy plus intraoperative balloon angioplasty. Furthermore, the primary potency rates were 77% at 1 month, 62% at 3 months, and 38% at 6 months. CONCLUSIONS: We recommend intraoperative balloon angioplasty plus surgical thrombectomy as an effective method of salvaging thrombosed hemodialysis grafts. However, since these are the initial results for this kind of hybrid procedure from a single hospital, large-scale studies with long-term follow up are required.

Treatment of a thrombosed hemodialysis graft is an ideal application for a mechanical thrombectomy device. The soft, acute thrombus contained within the graft can be quickly macerated and removed with minimal risk of damaging native vascular endothelium. There are no universally accepted techniques for using mechanical thrombectomy devices to treat a thrombosed vascular access. To the contrary, there are a variety of thrombectomy methods that are currently utilized by interventional radiologists. Each device has its own niche and is best utilized for certain specific situations. A busy interventionalist should be familiar with several of these thrombectomy devices to most effectively treat the variety of clinical problems that may be encountered.

We report on a 3-year-old boy in whom a complete occlusive thrombus in the right femoral artery was removed rapidly and successfully using a hydrodynamic thrombectomy catheter. There was no bleeding complication, reocclusion, vascular injury, or loss of motor or sensory function. Hydrodynamic thrombectomy can be an important part of the treatment of thrombosis in children.

PURPOSE: To review the place of interventional radiology in arteriovenous access for hemodialysis. METHODS: Prophylactic dilation of stenoses greater than 50% associated with clinical abnormalities such as flow-rate reduction is warranted to prolong access patency. Stents are placed only in selected cases with clearly insufficient results of dilation but they must never overlap major side veins and obviate future access creation. Thrombosed fistulae and grafts can be declotted by purely mechanical methods or in combination with a lytic drug. RESULTS: The success rates are over 90% for dilation, with frequent resort to stents in central veins. Long-term results in the largest series are better in forearm native fistulae compared with grafts (best 1-year primary patency: 51% versus 40%). The success rates for declotting are better in grafts compared with forearm fistulae but early rethrombosis is frequent in grafts so that primary patency rates can be better for native fistulae from the first month's follow-up (best 1-year primary patency: 49% versus 26%). CONCLUSION: Radiology achieves results comparable with surgery, with minimal invasiveness and better venous preservation. However, wide variations in the results suggest that the degree of commitment of physicians might be as important as the type of technique used.