Thrombosed hemodialysis grafts: percutaneous mechanical balloon declotting versus thrombolysis

Interventions for thrombosed haemodialysis arteriovenous fistulas and grafts

BACKGROUND

Patients who present with problems with definitive dialysis access (arteriovenous fistula (AVF) or arteriovenous graft (AVG)) become catheter dependent (temporary access), a condition that often carries a higher risk of infections, central venous occlusions and recurrent hospitalisations. For AVG, primary patency rates are reported to be 30% to 90% in patients undergoing thrombectomy or thrombolysis. According to the National Kidney Foundation-Kidney Disease Outcomes Quality Initiative (NKF-KDOQI) guidelines, surgery is preferred when the cause of the thrombosis is a stenosis at the site of the anastomosis in thrombosed AVF. The European Best Practice Guidelines (EBPG) reported that thrombosed AVF may be preferably treated with endovascular techniques, but when the cause of thrombosis is in the anastomosis, surgery provides better results with re-anastomosis. Therefore, there is a need to carry out a systematic review to determine the effectiveness and safety of the intervention for thrombosed fistulae.

OBJECTIVES

This review aims to establish the efficacy and safety of interventions for failed AVF and AVG in patients receiving haemodialysis (HD).

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 28 January 2024 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, EMBASE, conference proceedings, the International Clinical Trials Registry Portal (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

The review included randomised controlled trials (RCTs) and quasi-RCTs in people undergoing HD treatment using AVF or AVG presenting with clinical or haemodynamic evidence of thrombosis. Patients had to have used an AVF or AVG at least once.

DATA COLLECTION AND ANALYSIS

Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

Our search strategy identified 14 eligible studies (1176 randomised participants) for inclusion in this review. We included three types of interventions for the treatment of thrombosed AVF and AVG: (1) types of thrombectomy, (2) types of thrombolysis and (3) surgical procedures. Most of the included studies had a high risk of bias due to a poor study design, a low number of patients and industry involvement. Overall, there was insufficient evidence to suggest that a specific intervention was better than another for the outcomes of failure, primary patency at 30 days, technical success and adverse events (both major and minor). Primary patency at 30 days may improve with surgical compared to mechanical thrombectomy (3 studies, 404 participants: RR 1.36, 95% CI 1.07 to 1.67); however, the evidence is very uncertain. Death, access dysfunction, successful dialysis, and SONG (Standards Outcomes in Nephrology) outcomes were rarely reported. The current review is limited by the small number of available studies with a limited number of patients enrolled. Most of the studies included in this review have a high risk of bias and a low or very low certainty of evidence. Further research is required to define the most effective and clinically appropriate technique for access dysfunction.

AUTHORS' CONCLUSIONS

It remains unclear whether any intervention therapy affects the patency at 30 days or failure in any thrombosed HD AV access (very low certainty of evidence). Future research will very likely change the evidence base. Based on the importance of HD access to these patients, future studies of these interventions among people receiving HD should be a priority.

[Percutaneous transluminal angioplasty combined with thrombolysis for acute thrombosis in arterio-venous fistula and graft]

OBJECTIVE

To evaluate the efficacy of ultrasound or fluoroscopic-guided percutaneous transluminal angioplasty (PTA) combined with thrombolysis for the treatment of acutely thrombosed arteriovenous fistula (AVF) or grafts (AVG).

METHODS

One hundred and ninety-two hemodialysed patients, in whom the thrombosed arterio-venous AVF or AVG developed less than 72 h and there were no contraindications for thrombolysis and PTA, underwent PTA combined with thrombolysis therapy in Sir Run Run Shaw Hospital of Zhejiang University from October 2014 to October 2017. Under ultrasound and/or fluoroscopic guidance, balloon catheter was introduced to thrombosis sites along a guide wire. Then the balloon was inflated and normal saline mixed with urokinase and heparin was injected for thrombolysis. After blood flow was restored, angioplasty was performed on vascular stenosed sites.

RESULTS

A total of 274 endovascular interventional operations were performed for 192 patients. The procedure success rate was 98.2%, clinical success rate was 93.8%and complication rate was 1.46%. The post-intervention primary patency rates for AVF group were 87.4%, 76.7%and 63.9%at 3, 6 and 12 months, respectively; while the post-intervention secondary patency rates were 93.7%, 91.6%and 83.0%, respectively. The post-intervention primary patency rates for AVG group were 60.7%, 51.5%and 43.1%at 3, 6 and 12 months, while the post-intervention secondary patency rates were 82.7%, 77.1%and 70.8%, respectively.

CONCLUSIONS

PTA combined with thrombolysis is an effective and safe therapeutic option for AVF and AVG thrombosis, which would prolong hemodialysis access and save vascular resources for hemodialyzed patients.

Transfemoral Venous Access Facilitates Upper Extremity Dialysis Interventions: Procedural Success and Clinical Outcomes

PURPOSE

To report technical success and clinical outcomes of transfemoral venous access for upper extremity dialysis interventions.

MATERIALS AND METHODS

A total of 15 patients underwent a transfemoral venous approach for fistulography (n = 4; 27%) or thrombectomy (n = 11; 73%) over a 14-month period. Access characteristics, sheath size, thrombectomy method, angioplasty site, fluoroscopy time, radiation dose, technical and clinical success, complications, and post-intervention primary and secondary patency rates were recorded.

RESULTS

Access type included arteriovenous fistulas (n = 10; 67%) and grafts (n = 5; 33%). The most common configuration was brachio-brachial (n = 6; 38%). Mean age of access was 37 months. Mean prior interventions were 4. Right CFV access was used in all patients using 6-8-French (most common: 7-French [n = 10; 67%]) sheaths. Most thrombectomies (n = 11; 73%) required both pharmacologic and mechanical maceration (n = 9; 82%). All accesses required angioplasty to treat underlying stenosis at the outflow vein (n = 12; 80%) or arteriovenous anastomosis (n = 9; 90%). Mean fluoroscopy time was 26.43 min. Air kerma and dose area product were 178.06 ± 225.77 mGy and 57,768.83 ± 87,553.29 μGym², respectively. Procedural and clinical success rates were 93% and 80%, respectively. Technical failure was due to persistent stenosis in one patient. Clinical failure was due to unsuccessful dialysis immediately following intervention in three patients. Mean post-intervention primary patency and secondary patency durations were 2.8 and 4.8 months, respectively. Primary patency rates at 1 and 3 months were 50% and 35%, respectively. Secondary patency rates at 1 and 3 months were 58% and 30%, respectively.

CONCLUSION

A transfemoral venous approach for intervention of upper extremity dialysis accesses may be a valuable adjunct to traditional approaches.

Complications Related to Percutaneous Thrombectomy of Hemodialysis Grafts

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.

Pre-emptive correction for haemodialysis arteriovenous access stenosis

BACKGROUND

Guidelines recommend routine arteriovenous (AV) graft and fistula surveillance (technology-based screening) in addition to clinical monitoring (physical examination) for early identification and pre-emptive correction of a stenosis before the access becomes dysfunctional. However, consequences on patient-relevant outcomes of pre-emptive correction of a stenosis in a functioning access as opposed to deferred correction, i.e. correction postponed to when the access becomes dysfunctional, are uncertain.

OBJECTIVES

We aimed to evaluate 1) whether pre-emptive correction of an AV access stenosis improves clinically relevant outcomes; 2) whether the effects of pre-emptive correction of an AV access stenosis differ by access type (fistula versus graft), aim (primary and secondary prophylaxis), and surveillance method for primary prophylaxis (Doppler ultrasound for the screening of functional and anatomical changes versus measurement of the flow in the access); and 3) whether other factors (dialysis duration, access location, configuration or materials, algorithm for referral for intervention, intervention strategies (surgical versus radiological or other), or study design) explain the heterogeneity that might exist in the effect estimates.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Specialised Register to 30 November 2015 using search terms relevant to this review.

SELECTION CRITERIA

We included all studies of any access surveillance method for early identification and pre-emptive treatment of an AV access stenosis.

DATA COLLECTION AND ANALYSIS

We extracted data on potentially remediable and irremediable failure of the access (i.e. thrombosis and access loss respectively); infection and mortality; and resource use (hospitalisation, diagnostic and intervention procedures). Analysis was by a random effects model and results expressed as risk ratio (RR), hazard ratio (HR) or incidence rate ratio (IRR) with 95% confidence intervals (CI).

MAIN RESULTS

We identified 14 studies (1390 participants), nine enrolled adults without a known access stenosis (primary prophylaxis; three studies including people using fistulas) and five enrolled adults with a documented stenosis in a non-dysfunctional access (secondary prophylaxis; three studies in people using fistulas). Study follow-up ranged from 6 to 38 months, and study size ranged from 58 to 189 participants. In low- to moderate-quality evidence (based on GRADE criteria) in adults treated with haemodialysis, relative to no surveillance and deferred correction, surveillance with pre-emptive correction of an AV stenosis reduced the risk of thrombosis (RR 0.79, 95% CI 0.65 to 0.97; I² = 30%; 18 study comparisons, 1212 participants), but had imprecise effect on the risk of access loss (RR 0.81, 95% CI 0.65 to 1.02; I² = 0%; 11 study comparisons, 972 participants). In analyses subgrouped by access type, pre-emptive stenosis correction did not reduce the risk of thrombosis (RR 0.95, 95% CI 0.8 to 1.12; I² = 0%; 11 study comparisons, 697 participants) or access loss in grafts (RR 0.9, 95% CI 0.71 to 1.15; I² = 0%; 7 study comparisons; 662 participants), but did reduce the risk of thrombosis (RR 0.5, 95% CI 0.35 to 0.71; I² = 0%; 7 study comparisons, 515 participants) and the risk of access loss in fistulas (RR 0.5, 95% CI 0.29 to 0.86; I² = 0%; 4 studies; 310 participants). Three of the four studies reporting access loss data in fistulas (199 participants) were conducted in the same centre. Insufficient data were available to assess whether benefits vary by prophylaxis aim in fistulas (i.e. primary and secondary prophylaxis). Although the magnitude of the effects of pre-emptive stenosis correction was considerable for patient-centred outcomes, results were either heterogeneous or imprecise. While pre-emptive stenosis correction may reduce the rates of hospitalisation (IRR 0.54, 95% CI 0.31 to 0.93; I² = 67%; 4 study comparisons, 219 participants) and use of catheters (IRR 0.58, 95% CI 0.35 to 0.98; I² = 53%; 6 study comparisons, 394 participants), it may also increase the rates of diagnostic procedures (IRR 1.78, 95% CI 1.18 to 2.67; I² = 62%; 7 study comparisons, 539 participants), infection (IRR 1.74, 95% CI 0.78 to 3.91; I² = 0%; 3 studies, 248 participants) and mortality (RR 1.38, 95% CI 0.91 to 2.11; I² = 0%; 5 studies, 386 participants).In general, risk of bias was high or unclear in most studies for many domains we assessed. Four studies were published after 2005 and only one had evidence of registration within a trial registry. No study reported information on authorship and/or involvement of the study sponsor in data collection, analysis, and interpretation.

AUTHORS' CONCLUSIONS

Pre-emptive correction of a newly identified or known stenosis in a functional AV access does not improve access longevity. Although pre-emptive stenosis correction may be promising in fistulas existing evidence is insufficient to guide clinical practice and health policy. While pre-emptive stenosis correction may reduce the risk of hospitalisation, this benefit is uncertain whereas there may be a substantial increase (i.e. 80%) in the use of access-related procedures and procedure-related adverse events (e.g. infection, mortality). The net effects of pre-emptive correction on harms and resource use are thus unclear.

Efficacy of a modified pharmacomechanical thrombolysis technique for endovascular treatment of thrombosed prosthetic arteriovenous grafts

Objective

We applied a modified pharmacomechanical thrombolysis (PMT) technique to endovascular treatment of thrombosed arteriovenous (AV) grafts without the use of any mechanical thrombectomy devices. The aim of this study was to evaluate the efficacy of the PMT technique in the treatment of thrombosed AV grafts by analyzing the long-term patency.

Materials and Methods

Eighty-two patients with thrombosed AV grafts were treated with the PMT technique. AV graft surveillance to detect failing/failed access was followed by endovascular treatment.

Results

The technical and clinical success rates were 95% and 95%, respectively. The total number of thrombolysis sessions was 279. A post-intervention primary patency rate was 45% and 22% at 12 and 24 months, respectively. The secondary patency rate was 96% and 91% at 12 and 24 months, respectively. No major complications were noticed.

Conclusion

The modified PMT technique is effective in endovascular treatment of thrombosed AV grafts.

Paradoxical embolism after declotting of hemodialysis fistulae/grafts in patients with patent foramen ovale

BACKGROUND AND OBJECTIVES

The safety of percutaneous endovascular declotting procedures for thrombosed hemodialysis fistulae/grafts is well described in the general population; however, its safety in the presence of a patent foramen ovale (PFO) is not known. The objective of this study is to assess the incidence of symptomatic paradoxical embolic events associated with declotting procedure of thrombosed arteriovenous (AV) graft or fistula in patients with documented PFO.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a retrospective study in a hospital-based, academic practice. It included 23 patients (10 men; mean age, 65) with PFO and thrombosed hemodialysis graft/fistula who underwent a standardized declotting procedure with 2 mg of Alteplase and balloon thrombectomy. Twenty patients (87%) had AV grafts, and three (13%) had AV fistulae. The PFO shunt was right to left in two (9%), left to right in eight (34%), and bidirectional in ten (44%). The shunt direction was not specified in three patients (13%). The technical success of the declotting procedure and the frequency of clinically manifested paradoxical embolic events in this patient population were calculated.

RESULTS

Fifty declotting procedures were performed on 23 patients with a technical success rate of 96% (48 of 50, 96%). No symptomatic paradoxical embolic events were found in any of the 23 patients with PFO.

CONCLUSIONS

Symptomatic paradoxical embolic events after percutaneous endovascular declotting procedures of thrombosed AV grafts and fistulae in patients with documented PFO are rare. This procedure appears to be safe in patients with a PFO.

Radiation exposure in dialysis access-related procedures decreases with increase in number of procedures performed by the interventional nephrologist

An appreciation of the inherent risks with radiation exposure to patients and to the physician performing the procedure and the staff is urgently needed. The objective of this study is to assess radiation exposure to both patients and interventional nephrologists performing procedures and see any trends in the procedure and fluoroscopy times over a 2-year period. A total of 400 procedures performed at our vascular access center by a new to practice interventional nephrologist were recorded and retrospectively analyzed. Fluoroscopic time and procedure time for various procedures over the course of 2 years were recorded. This data were subsequently separated into eight groups (four quarters per year) based on the date of the procedure. Our study demonstrates a decrease in mean and median fluoroscopy times and procedure times for newly trained interventional with gain in number of procedures. The mean fluoroscopy time for the first two quarters was 5 minutes and 4 seconds, and the median was 3 minutes and 37 seconds. The mean procedure time for the first two quarters was 38 minutes, and the median was 32 minutes. The mean fluoroscopy time for the last two quarters was 1 minute and 54 seconds, and the median was 1 minute and 26 seconds. The mean procedure time for the last two quarters was 27 minutes, and the median was 21 minutes. In conclusion, gain of experience by the practicing Interventional Nephrologist from performing an increasing number of procedures leads to decreased procedure times and fluoroscopy times, which lowers the risk of radiation.

Phase 1 study of human plasma-derived plasmin (TAL-05-00018) in hemodialysis graft occlusion

INTRODUCTION

Hemodialysis grafts often fail because of stenosis at the venous anastomosis resulting in thrombosis. Percutaneous intervention involves thrombolysis with plasminogen activators, mechanical removal of thrombus, and angioplasty of the stenotic lesions.

OBJECTIVES

This article describes a phase I trial using plasmin (human) TAL 05-00018, a direct-acting fibrinolytic agent, to evaluate safety and, secondarily, to establish effective thrombolytic dosing.

PATIENTS/METHODS

Six cohorts of five patients with acute HD graft occlusion documented by fistulagrams were treated with increasing dosages of plasmin (1, 2, 4, 8, 12, and 24 mg) infused within the graft over 30 min via two criss-crossed pulse-spray catheters. The primary efficacy endpoint was at least 50% thrombolysis, as determined by fistulography.

RESULTS

There was no significant change in plasma alpha-2 antiplasmin or fibrinogen concentration, major bleeding did not occur, and there were no deaths. Serious adverse events in four patients were not related to the study drug. There was a dose-response relationship for the primary efficacy endpoint, all five subjects receiving 24 mg achieving more than 75% lysis.

CONCLUSION

This first phase I study of plasmin (human) TAL 05-00018, infused into thrombosed HD grafts, documents safety at all doses and an effective thrombolytic dosage of 24 mg indicating that further investigation into locally delivered plasmin is warranted.

A first-in-human phase I trial of locally delivered human plasmin for hemodialysis graft occlusion

BACKGROUND

Hemodialysis (HD) grafts often fail because of stenosis at the venous anastomosis and thrombotic occlusion. Percutaneous management relies on thrombolysis with plasminogen activators, mechanical removal of thrombus, and angioplasty of the stenotic lesion.

OBJECTIVES

This report describes a phase I trial using Plasmin (Human) TAL 05-00018, a direct-acting fibrinolytic agent, to evaluate safety and, secondarily, to establish effective thrombolytic dosing.

PATIENTS/METHODS

Six cohorts of five patients with acute HD graft occlusion documented by angiography were treated with escalating dosages of plasmin (1, 2, 4, 8, 12, and 24 mg) infused over 30 min via criss-crossed pulse-spray catheters within the graft. The primary efficacy endpoint was > or =50% thrombolysis, as determined by comparison of pre-plasmin and 30-min post-plasmin fistulograms.

RESULTS

Of 31 subjects who received study drug (safety population), one withdrew and 30 completed the trial (evaluable for efficacy). There was no significant change in plasma alpha-2 antiplasmin or fibrinogen concentration, major bleeding did not occur, and there were no deaths. Serious adverse events in four patients were not related to the study drug. There was a dose-response relationship for the primary efficacy endpoint, all five subjects receiving 24 mg achieving >75% lysis.

CONCLUSIONS

This first phase I study of Plasmin (Human) TAL 05-00018, infused into thrombosed HD grafts, documents safety at dosages of 1-24 mg and an effective thrombolytic dosage of 24 mg. The results establish a foundation for further clinical study of catheter-based plasmin administration in thrombotic disorders.

Surgical versus percutaneous care of arteriovenous access

Current clinical practice patterns have led to the performance of many percutaneous vascular procedures outside the traditional operating room and led to significant changes in management strategies for treatment of complications of arteriovenous access. In an effort to identify optimal treatment for failed or failing arteriovenous fistulas and grafts, percutaneous and surgical techniques are analyzed. Assessment of the functioning or failing access by physical examination is critical in determining proper treatment and in assessing outcomes of interventions. Percutaneous and surgical techniques are available for the treatment of AV access thrombosis and venous stenosis. Techniques for percutaneous thrombectomy and stent placement for venous stenosis and AV graft pseudoaneurysms are reviewed. Management of arterial inflow disease, steal syndrome and nonmaturing AV fistulas is also addressed. Overall, percutaneous techniques are assuming an increasingly important role in the treatment of failed or failing AV fistulas and grafts. Ongoing analysis of outcomes of both percutaneous and surgical interventions is necessary to continue to identify optimum treatment algorithms.

Percutaneous treatment of failed native dialysis fistulas: use of pulse-spray pharmacomechanical thrombolysis as the primary mode of therapy

Objective

To determine the efficacy and outcome of percutaneous treatment in restoring the function of failed native arteriovenous fistulas (AVFs) where pulse-spray pharmacomechanical thrombolysis was used as the primary mode of therapy.

Materials and Methods

From June 2001 to July 2005, 14 patients who had thrombosis of native AVFs underwent percutaneous restoration following 20 episodes of thrombosis. These included 6 repeated episodes in one forearm AVF and two episodes in another forearm AVF. All patients except one were treated with urokinase injection utilizing the pulse-spray technique and had subsequent balloon angioplasty. One patient was treated by percutaneous angioplasty alone. We retrospectively evaluated the feasibility of percutaneous treatment in restoring the function of the failed AVFs. The primary and secondary patencies were calculated by using a Kaplan-Meier analysis.

Results

Both technical and clinical success were achieved in 15 (75%) of 20 AVFs. Four of the five technical failures resulted from a failure to cross the occluded segment. One patient refused further participation in the trial through a brachial artery access following failure to cross the occluded segment via an initial retrograde venous puncture. There were no major precedure related complications observed. Including the initial technical failures, primary patency rates at six and 12 months were 64% and 55%, respectively. Secondary patency rates at six and 12 months were 71% and 63%, respectively.

Conclusion

Pulse-spray pharmacomechanical thrombolysis for treatment of the thrombosed AVFs is safe, effective and durable. This procedure should be considered as an option for the management of failed AVFs prior to surgical intervention.

Vascular injury caused by mechanical thrombectomy in porcine arteries: AKónya eliminator device versus Arrow-Trerotola percutaneous thrombolytic device

PURPOSE

To compare vascular injuries induced by a nonrotational thrombectomy device equipped with an adjustable basket (the AKónya Eliminator [AKE] device) and the Arrow-Trerotola percutaneous thrombolytic device (PTD) in porcine external iliac arteries (EIAs).

MATERIALS AND METHODS

The EIAs of nine domestic pigs underwent simulated thrombectomy with the AKE after the diameter of the basket had been adjusted to the vessel's diameter and with the PTD after motor activation. Three animals were euthanized immediately after treatment (group 1, acute), three after 1 week (group 2, subchronic), and three after 6 weeks (group 3, chronic). Vessel diameters were measured angiographically at four anatomic locations at the three time points. A histologic grading system was established to quantify the degree of vascular injury and lumen compromise. Four other EIAs were treated with an "oversized" AKE basket and followed for 6 weeks.

RESULTS

Histologically, the acute lesions in the AKE-treated vessels were more superficial than those in the PTD-treated vessels. In group 2, two of three PTD-treated arteries occluded, and their subchronic injuries were more serious than those in the AKE-treated arteries. In group 3, all AKE-treated arteries remained patent, but one of the PTD-treated vessels occluded, and the lumen sizes of the PTD- and AKE-treated arteries differed significantly. After 6 weeks, there was no significant difference between arteries treated with the PTD and those treated with the oversized AKE in terms of diameter or histologic grading.

CONCLUSIONS

The adjustable basket and hand-controlled operation of the AKE were significantly less injurious to the arterial wall than the constant-size PTD basket operated at 3,000 rpm. Damage produced by the oversized AKE basket was similar to that produced by the PTD.

Percutaneous declotting of virgin femoral hemodialysis grafts

OBJECTIVE

The objective of our study was to evaluate outcomes of percutaneous declotting procedures in patients with prosthetic femoral dialysis grafts.

MATERIALS AND METHODS

A retrospective review of all pharmacomechanical femoral dialysis graft declotting procedures performed in our hospital between May 11, 1993, and April 30, 2003, was performed. A total of 110 procedures were performed on 25 patients (nine males, 16 females; age range, 17-80 years; mean age, 49 years) with 30 grafts.

RESULTS

Technical success was 97.3%. Using life table analysis, 30-day postinterventional primary patency was 72%, 90-day primary patency was 46%, 180-day primary patency was 25%, and 365-day primary patency was 4%. The 30-day secondary postinterventional patency was 93%, 90-day secondary patency was 86%, 180-day secondary patency was 76%, and the 365-day secondary patency was 51%. An average of 1.96 declotting procedures were performed per year of dialysis.

CONCLUSION

Percutaneous declotting of femoral hemodialysis grafts has technical success and patency rates similar to those for percutaneous declotting in the upper extremities. Results of this series exceeded criteria established by the National Kidney Foundation in the "Dialysis Outcome Quality Initiative" for immediate patency and unassisted 3-month patency.

A new mechanical device for declotting of hemodialysis access grafts: first clinical experience

PURPOSE

To review the early clinical experience with a new mechanical thrombectomy device for declotting polytetrafluoroethylene (PTFE) hemodialysis access (HDA) grafts.

METHODS

The XTD is a 6-F introducer-compatible device that pulverizes clot with a rotating curved tip driven by a flexible spiral shaft. Fragments are aspirated into a collection container. Fifty patients (32 women; mean age 66 years) with clotted 6-mm polytetrafluoroethylene HDA grafts were treated at 2 medical centers in a study spanning 22 months. In all, 59 procedures were performed on an outpatient basis under monitored conscious sedation. Ancillary techniques were used as needed to treat the underlying cause of the clot. Technical success was defined on a per-procedure basis as removal of sufficient thrombus to visualize the underlying disease without major device-related complications.

RESULTS

Technical success was 100%; no device-related adverse events occurred. Immediate clinical success was achieved in 47/59 (80%) cases. Continued clinical success in survivors was 52% (30/58) at 1 month and 46% (26/56) at 3 months. Eliminating from analysis a high-risk patient subgroup (reocclusions, chronically clotted or unsalvageable grafts, untreatable central venous stenosis, and venous anastomoses resistant to wire/catheter passage) increased the 3-month clinical success to 59% (22/37).

CONCLUSIONS

The XTD is a promising device capable of safely and effectively declotting PTFE grafts. Further investigation is warranted.

Effectiveness and safety of dialysis vascular access procedures performed by interventional nephrologists

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.

Pharmacomechanical Thrombolysis of Dialysis Access Grafts Using the MTI Castañeda Over-the-Wire Brush Catheter and Reteplase

Pharmacomechanical thrombolysis (PMT) has emerged as an alternate treatment used in most patients presenting with a thrombosed hemodialysis graft. Although the gold standard, surgical revision of thrombosed hemodialysis grafts is reserved for those cases of recurrent thrombosis despite the use of percutaneous techniques and for complicated cases after PMT. Nevertheless, as for every other procedure, PMT has its own set of limitations and cost issues. New mechanical devices have begun to emerge on the market to help accelerate clot dissolution with or without thrombolytic medications. These devices have decreased the time required to lyse clot and decrease the overall cost of percutaneous treatment. This article describes the use of the Microtherapeutics, Inc. (MTI) Castañeda over-the-wire brush and our experience with this device in the treatment of the clotted hemodialysis graft.

Percutaneous treatment of complications occurring during hemodialysis graft recanalization

INTRODUCTION/OBJECTIVE

To describe and evaluate percutaneous treatment methods of complications occurring during recanalization of thrombosed hemodialysis access grafts.

METHODS AND MATERIALS

A retrospective review of 579 thrombosed hemodialysis access grafts revealed 48 complications occurring during urokinase thrombolysis (512) or mechanical thrombectomy (67). These include 12 venous or venous anastomotic ruptures not controlled by balloon tamponade, eight arterial emboli, 12 graft extravasations, seven small hematomas, four intragraft pseudointimal 'dissections', two incidents of pulmonary edema, one episode of intestinal angina, one procedural death, and one distant hematoma.

RESULTS

Twelve cases of post angioplasty ruptures were treated with uncovered stents of which 10 resulted in graft salvage allowing successful hemodialysis. All arterial emboli were retrieved by Fogarty or embolectomy balloons. The 10/12 graft extravasations were successfully treated by digital compression while the procedure was completed and the graft flow was restored. Dissections were treated with prolonged Percutaneous Trasluminal Angioplasty (PTA) balloon inflation. Overall technical success was 39/48 (81%). Kaplan-Meier Primary and secondary patency rates were 72 and 78% at 30, 62 and 73% at 90 and 36 and 67% at 180 days, respectively. Secondary patency rates remained over 50% at 1 year. There were no additional complications caused by these maneuvers.

DISCUSSIONS AND CONCLUSION

The majority of complications occurring during percutaneous thrombolysis/thrombectomy of thrombosed access grafts, can be treated at the same sitting allowing completion of the recanalization procedure and usage of the same access for hemodialysis.

Original report. Pulse-spray thrombolysis of thrombosed hemodialysis grafts with tissue plasminogen activator

OBJECTIVE

The purpose of this study was to evaluate pulse-spray pharmacomechanical thrombolysis with the use of tissue plasminogen activator in the recanalization of thrombosed hemodialysis access grafts.

CONCLUSION

Pulse-spray pharmacomechanical thrombolysis with tissue plasminogen activator is an effective method for percutaneous recanalization of thrombosed hemodialysis access grafts with results similar to other percutaneous techniques.

Improving dialysis access management

Renal replacement therapy requires either placement of a functional hemodialysis vascular access or peritoneal dialysis catheter. Early provision of a dialysis access improves patient care with reduction in morbidity and reduces the economic burden incurred as a result of delayed access placement. Vascular access dysfunctions (thrombosis and infection) pose the greatest burden on the end-stage renal disease population. This article reviews the current literature on the planning of dialysis access, with particular emphasis on issues pertaining to vascular access. Current concepts to maximize access patency and efficiently manage vascular access complications are highlighted.

Alteplase for hemodialysis access graft thrombolysis

PURPOSE

To evaluate the efficacy and safety of alteplase, a recombinant tissue plasminogen activator, in hemodialysis access graft thrombolysis.

MATERIALS AND METHODS

From November 1999 to May 2001, 68 episodes of occlusion in 50 grafts (in 49 patients) were included in the study. Occlusion was treated with pulse-spray (n = 41) or lyse-and-wait (n = 27) thrombolysis with use of alteplase. Balloon angioplasty of all identified stenoses was performed. The arterial plug was mobilized with the Fogarty maneuver.

RESULTS

Procedural success was achieved in 64 of 68 episodes (94%) with a dose of 2-10 mg (mean = 4.13 mg) of alteplase, allowing successful hemodialysis within 24 hours. Failures (6%) were the result of PTA perforation (one of 68), nonnegotiable outflow occlusion (one of 68), delayed bleeding (one of 68), and balloon bursting and shearing becoming occlusive within the graft (one of 68). Primary and secondary patency rates were 72% and 87% at 30 days, 57% and 80% at 90 days, and 44% and 72% at 180 days, respectively. Arterial emboli (two of 68) were treated by Fogarty balloon retrieval and alteplase infusion locally over the course of 20 minutes. One of two PTA perforations was controlled by balloon tamponade.

CONCLUSION

Alteplase can be used successfully for hemodialysis graft thrombolysis.

The role of vascular radiology in hemodialysis access

The article summarizes the role of vascular radiology in the imaging and salvage of hemodialysis fistulas and in the placement and maintenance of tunneled dialysis access catheters.

Restoration of thrombosed Brescia-Cimino dialysis fistulas by using percutaneous transluminal angioplasty

PURPOSE

To evaluate the authors' experience with a technique for management of thrombosed Brescia-Cimino arteriovenous fistula.

MATERIALS AND METHODS

Forty patients with 42 thrombosed arteriovenous fistulas were percutaneously treated. Thrombosis occurred within 24 hours of attempted angioplasty in five fistulas, between 24 and 72 hours in 27, and longer than 72 hours in 10. Thrombosed fistulas were approached in a retrograde fashion followed by direct balloon dilation with 5-8-mm balloon catheters. If retrograde catheterization failed to cross the arterial anastomosis, an antegrade puncture directly into the thrombosed drainage vein close to the anastomosis was performed with ultrasonographic guidance, as an aid to catheterize the arterial inflow. Thrombolytic therapy with infusion of urokinase directly into the thrombus was performed in selected patients with visible thrombus that had compromised blood flow in the partially restored vascular access. Postintervention primary and secondary patency was calculated by using Kaplan-Meier analysis. Patency rates between patients without and with urokinase infusion were examined by using the log-rank test.

RESULTS

Anatomic success was achieved in 39 (93%) of 42 fistulas; and clinical patency, in 38 (90%) of 42 fistulas. Postintervention primary and secondary patencies (including initial technical failure) at 6, 12, and 18 months were 81% and 84%, 70% and 80%, and 63% and 80%, respectively. No significance of patency rate between patients without and with urokinase infusion was found (P =.912). Three patients died of unrelated causes at 1, 2, and 5 months after the procedures. No major complications were encountered.

CONCLUSION

High anatomic success and excellent clinical patency can be achieved in the salvage of thrombosed arteriovenous fistulas. Percutaneous restoration of arteriovenous fistulas should be attempted before surgical recreation to optimize outcome in patients undergoing hemodialysis.

Reteplase in the treatment of thrombosed hemodialysis grafts

PURPOSE

To prospectively evaluate the efficacy and safety of reteplase with percutaneous transluminal angioplasty (PTA) in the treatment of thrombosed polytetrafluoroethylene hemodialysis arteriovenous grafts (AVGs).

MATERIALS AND METHODS

Forty-two patients were entered into the study. Sixty-two procedures in 43 grafts were performed. One unit of reteplase and 4,000 units of heparin were administered into the AVGs. Routine venography and percutaneous transluminal angioplasty (PTA) was then performed. Patients were transferred for hemodialysis immediately after the procedure.

RESULTS

Technical success was achieved in 92% of the cases. Four cases involved intentional repeat thrombosis because of poor outflow and/or need for a new graft site. Minor complications occurred in 6.5% of the cases. No major complications occurred. The mean procedure time for experienced versus less-experienced interventionalists was significantly shorter (P <.001). Primary patency rates were 50%, 34%, and 34% at 30, 90, and 180 days, respectively.

CONCLUSION

Reteplase in conjunction with heparin and PTA is a safe and effective means of thrombolysis of AVGs. Its efficacy is comparable to that of other available thrombolytic drugs.

Thrombosed hemodialysis grafts: lyse and wait with tissue plasminogen activator or urokinase compared to mechanical thrombolysis with the Arrow-Trerotola Percutaneous Thrombolytic Device

PURPOSE

To determine if the lyse and wait (L&W) technique with a 4-mg dose of alteplase (tissue plasminogen activator; tPA) is a safe and effective method of declotting dialysis grafts as compared to use of the Arrow-Trerotola Percutaneous Thrombectomy Device (PTD) or the L&W technique with use of urokinase (UK).

MATERIALS AND METHODS

Forty patients were randomized prospectively to undergo L&W declotting with use of 4 mg of tPA or mechanical thrombolysis with the PTD. The time interval to restored graft flow, total procedure time, hemostasis time, and anatomic success, clinical success, complications, and patency rates were analyzed. These were compared with historic results in 20 patients treated with the L&W technique with use of 250,000 U UK.

RESULTS

The immediate anatomic success rate was 95% in the tPA L&W and PTD groups. The mean in-room lysis time with restored flow was 10 minutes for L&W with tPA and 19 minutes for PTD (P = .002). The mean in-room procedure time was 39 minutes for L&W and 45 minutes for PTD (P = NS). Mean hemostasis time with use of manual compression was 44 minutes for L&W with tPA and 23 minutes for PTD (P = .057). The historic group of 20 patients who underwent L&W with UK had a 95% anatomic success rate, a mean of 14 minutes of lysis time, a mean of 34 minutes of procedure time, and a mean of 26 minutes of time to hemostasis. No bleeding complications occurred in the PTD group. Seven episodes of bleeding occurred in six patients given tPA; four were delayed 60-90 minutes after the procedure, one necessitated hospitalization, and two required additional therapies. Four of the 20 patients undergoing L&W with UK had minor puncture site bleeding during the procedure. The 3-month primary patency rates were 65%, 65%, and 60% for L&W with tPA, PTD, and L&W with UK, respectively (P = NS).

CONCLUSION

The 4-mg dose of tPA is effective but results in more bleeding complications and longer hemostasis times than mechanical thrombolysis with use of the PTD. Unlike in our experience with UK, bleeding complications with tPA were both major and delayed.

Contemporary treatment of thrombosed hemodialysis grafts

Maintaining hemodialysis grafts remains a difficult problem. Before the early 1990s, graft declotting was usually performed in the surgical suite. Percutaneous declotting has been evolving since the mid-1980s. Initially, a low-dose thrombolytic infusion of streptokinase through a single catheter was used. Crossing catheters with a higher-dose infusion of urokinase was then introduced. This technique was modified with the adjunctive use of pharmacomechanical techniques with the use of compliant balloons and the adjunctive use of heparin. The advent of the "lyse-and-wait" technique provided a simpler and quicker way to declot thrombosed grafts by using urokinase, with similar outcomes. Since the removal of urokinase from the market, multiple mechanical devices have been used with similar success. Recent reports concerning the use of newer-generation thrombolytic agents report similar outcomes, with a reduction in total cost.

Comparison of three mechanical thrombus removal devices in thrombosed canine iliac arteries

PURPOSE

To assess and compare intimal and medial vascular damage caused by three mechanical wall-contact thrombectomy devices: Fogarty embolectomy catheter, Arrow-Trerotola peripheral thrombectomy device, and MTI-Castañeda over-the-wire brush.

MATERIALS AND METHODS

Bilateral external iliac arteries of 15 canines were thrombosed before mechanical thrombolysis. Ten thrombosed arteries were randomly assigned to receive each device. Animals were sacrificed immediately, and histologic assessment of endothelial and medial damage in the vessels was performed.

RESULTS

The vascular damage found with all devices extended into the tunica media. The Fogarty embolectomy catheter and the Arrow-Trerotola device caused significantly more damage than the Castañeda brush.

CONCLUSION

All devices caused lesions extending into the media. Previous research has shown that the extent and depth of the vascular lesion may be contributing factors in promoting early atherosclerotic and accelerated hyperplastic intimal and medial changes. These findings warrant further study of these devices in an atherosclerotic model with longer follow-up.

Short-term patency and safety of an expanded polytetrafluoroethylene encapsulated endoluminal device at the venous anastomosis of a canine arteriovenous graft model

PURPOSE

To determine the safety and short-term patency of a polytetrafluoroethylene (PTFE)-encapsulated carbon-lined endoluminal device (ED) deployed across the venous anastomosis of arteriovenous conduits.

MATERIALS AND METHODS

Arteriovenous grafts (n = 16) were created between femoral arteries and veins in eight female canines and allowed to mature 30 days +/- 5 (SD). Five were excluded before implantation because of thrombosis or intragraft stenosis. Deployment was conducted in the remaining 11 anastomoses. Fistulography and intravascular ultrasound (IVUS) were performed before and after the procedure and 1 month postimplantation. Stent migration, apposition, and stenosis were evaluated. The angle of the anastomosis was compared before and after deployment and at follow-up. Mural thrombus thickness, percentage of surface covering, and percentage of endothelialization within the device were measured histologically.

RESULTS

There was no significant migration. By explant, all devices were completely apposed. Stenosis occurred in three of nine grafts. The angle of the venous anastomosis decreased by 29.5 degrees (posteroanterior) and 32.4 degrees (oblique) after ED deployment. There was a further decrease of 6.1 degrees (posteroanterior) and 3.2 degrees (oblique) during the 4-week follow-up period. Hemostasis was difficult to achieve in this animal model. Five required more than 1 hour to achieve hemostasis manually. Six in three animals were closed with a Perclose device, achieving immediate hemostasis; however, three (one in each animal) re-bled intermittently 2 weeks after implantation for an average of 9.3 days. The puncture site of each graft that bled was radiographically shown abnormal.

CONCLUSION

The ED can be deployed without stent migration and is completely apposed and patent after 4 weeks. Although bleeding was a problem with this animal model, delayed bleeding complications associated with puncture site abnormalities were seen only in grafts closed with a percutaneous suturing device.

Vascular access for haemodialysis

BACKGROUND

The recent expansion of renal replacement therapy programmes has been associated with an increase in the number and complexity of patients requiring permanent vascular access. The introduction of strategies designed to maximize secondary access patency is, therefore, increasingly important as a means of prolonging patient survival on dialysis, reducing morbidity and reducing the escalating cost of such programmes.

METHODS

A review of the current literature on the planning of vascular access, access surveillance methods and treatment of the most common complications was performed.

RESULTS

Multidisciplinary vascular access planning, increased use of preoperative imaging and the preferential use of autogeneous vein are essential to obtain the best long-term results. While vascular access surveillance, in particular protocols involving direct measurement of access flow, enables the prospective detection and treatment of venous stenosis, the precise indications for treating venous stenosis remain unclear. Surgical revision remains the gold standard for the treatment of failing arteriovenous fistulas, but recent advances in interventional radiological techniques along with the suitability of arteriovenous fistulas for percutaneous intervention may offer an effective alternative. The effect of both these interventions on access patency requires comparison in a randomized trial.

CONCLUSION

The introduction of strategies to improve access patency rates will change vascular access surgical practice away from the construction of new fistulas towards an increase in outpatient percutaneous intervention and surgical revisional procedures. The role of surgical interventions requires clearer definition.

Pulmonary embolism from pulse-spray pharmacomechanical thrombolysis of clotted hemodialysis grafts: urokinase versus heparinized saline

PURPOSE

To compare the frequency and extent of pulmonary embolism (PE) occurring during pulse-spray pharmacomechanical thrombolysis (PSPMT) of clotted hemodialysis grafts with use of either urokinase (UK) or heparinized saline (HS). Postintervention primary patency and complication rates were compared for each method of thrombolysis.

METHODS AND MATERIALS

Twenty-seven patients were enrolled in this prospective, randomized, double-blind study evaluating PE with two PSPMT agents. The doses of heparin were similar between groups. The only variable was that one group of patients received UK and the other received HS. In two cases, the venous anastomosis could not be crossed. Eleven patients were treated with UK and 14 with HS. Nuclear medicine perfusion lung scans were performed before treatment and after graft declotting procedures. Lung perfusion was quantified to 10% of a pulmonary segment (0 = normal perfusion, 1 = segmental perfusion defect), with nine segments counted for each lung.

RESULTS

Baseline nuclear medicine perfusion lung scan results were abnormal (> or = 20% segmental perfusion defect) in 19 patients (70.4%). New PE (one or more pulmonary segments) occurred in two patients treated with UK (18.2%) and nine patients treated with HS (64.3%; P = .04). All cases of PE were asymptomatic. Quantitative global pulmonary perfusion analyses revealed that treatment with UK improved flow to 0.2 +/- 2.0 pulmonary segments, whereas treatment with HS decreased perfusion to 1.0 +/- 1.7 segments (P = .16, NS). Although postintervention primary patency rates were similar according to life-table analysis (P = .76, NS), complication rates were higher with use of HS (n = 4, 28.6%) than with use of UK (n = 2, 18.2%) (P = .6, NS).

CONCLUSIONS

All PE were asymptomatic during PSPMT, but treatment with UK reduced the rate of PE and tended to result in smaller defects in lung scan results. Most patients undergoing hemodialysis have abnormal baseline perfusion scan results, but PSPMT with UK improved many of them. The postintervention primary patency rates were similar between groups, but complications were more frequent after treatment with HS.

Early rethrombosis of clotted hemodialysis grafts: graft salvage achieved with an aggressive approach

OBJECTIVE

The purpose of this study was to assess the efficacy of repeated pulsed spray pharmacomechanical thrombolysis for salvage of early rethrombosis of hemodialysis grafts and to identify factors that predict successful outcome.

MATERIALS AND METHODS

Thirty-four patients with initial successful thrombolysis were referred for repeated thrombolysis because of early rethrombosis. Repeated thrombolysis occurred within 1 month of initial thrombolysis. Technical success and patency rates were calculated. Causes of graft thrombosis and procedural modifications were analyzed.

RESULTS

The 39 rethrombosed grafts were successfully treated using pharmacomechanical thrombolysis, and patients underwent subsequent hemodialysis. The underlying flow-limiting stenoses were treated with balloon angioplasty using a larger balloon (41%), a same-size angioplasty balloon (18%), stent placement (15%), or increased anticoagulation (5%). A new stenosis location was discovered in 18%. Mean primary patency was 80.9 days (2.6 months) and secondary patency was 235.4 days (7.8 months). With life table analysis, 1-, 3-, 6-, and 12-month primary patency rates were 72%, 31%, 23%, and 15%, and secondary patency rates were 77%, 62%, 51%, and 31%, respectively. Graft patency rates in our study were compared with our institutional historic graft patency rates, with no significant difference noted (p = 0.76). No major procedural complications occurred.

CONCLUSION

Adequate technical success and patency rates for pharmacomechanical thrombolysis occur even for hemodialysis grafts that rethrombose within 1 month. After thrombolysis, aggressive search for and treatment of additional stenoses are warranted.

Recanalization of thrombosed dialysis access with use of a rotating mini-pigtail catheter: follow-up study

PURPOSE

To evaluate the feasibility, efficacy, and safety of mechanical thrombectomy of occluded dialysis access with use of a rotating mini-pigtail catheter.

MATERIALS AND METHODS

Thrombus was fragmented by mechanical action of the rotating pigtail tip (5-mm diameter), while the guide wire exited a sidehole at the pigtail curvature and served as a fixed rotation axis. Twenty-six procedures were performed in 22 patients (12 men, 10 women; mean age, 55.5 years). Native fistulas were treated in 15 instances, polytetrafluoroethylene (PTFE) grafts were treated in 11 instances. Average occlusion time was 20 hours +/- 13 (range, 5-46 hours), average occlusion length was 25.6 cm +/- 10.1 (range, 6-45 cm). Thrombus fragmentation was followed by balloon angioplasty of underlying stenoses.

RESULTS

In all 26 procedures, the dialysis access was successfully declotted with subsequent dialysis using the access (clinical success rate, 100%). Handling of the mini-pigtail catheter was simple and rapid, regardless of whether a graft or a native fistula was treated. Average duration of the intervention was 118 minutes +/- 30. Mean primary patency was 165 days +/- 167. Primary patency rate was 82% at 30 days, 65% at 3 months, and 47% at 6 months. There was no evidence of complications due to the thrombus fragmentation procedure.

CONCLUSION

The results suggest that declotting of occluded dialysis grafts and fistulas with the mini-pigtail catheter is as effective and safe as other more established percutaneous therapies. It may serve as an easy-to-handle, low-budget alternative to current thrombectomy devices.

Outpatient percutaneous transluminal renal artery angioplasty: a Canadian experience

PURPOSE

The authors performed a retrospective study of their experience and complication rate while performing outpatient percutaneous transluminal renal artery angioplasty (PTRA) during a 5-year period.

MATERIALS AND METHODS

From July 1992 to July 1997, 87 PTRAs were performed. Of these, 62 PTRA procedures were performed on 53 outpatients. In total, 66 arteries were dilated in 62 PTRA sessions using standard, established techniques. During the same period, only 25 PTRAs were performed on inpatients. Angioplasties were performed on those patients with demonstrated renal artery stenosis and poorly controlled hypertension and/or renal failure. Patients chosen for PTRA were picked by a team that included a vascular surgeon, a nephrologist, and a radiologist. Patients who were deemed suitable for an outpatient procedure were recommended by a nephrologist. Radiological input was sought at that time. Specific guidelines were used to select these patients who were otherwise healthy, well-orientated, and able to respond to an emergency situation. None of the subjects had significant risk factors. All were accompanied by an adult for the first 24 hours and all lived no more than an hour's travel time from a hospital. All were stable on discharge and were seen within 24 hours by a nephrologist.

RESULTS

The technical success rate, defined as a residual stenosis on imaging of less than 30% and/or by a pressure gradient of less than 10 mm Hg across the stenosis, was 85%. The early complication rate was 5.6%, including two patients who developed a localized hematoma. In all, four patients were admitted to the hospital rather than being discharged to home after an average of 4.2 hours of observation. The late complication rate was 3% and involved two patients. One patient, who reported pain after balloon deflation, was readmitted 6 hours after discharge with hypotension, and a diagnosis of renal artery rupture was confirmed with computed tomography. Another patient developed peripheral atheroemboli 20 days after the procedure.

CONCLUSION

Outpatient PTRA can be performed on selected patients. In this study, late complications occurred in only 3% of patients. Early complications were readily recognized in 5.6% of patients, and these patients were admitted for observation after the procedure.

Transcatheter aspiration: the key to successful percutaneous treatment of deep venous thrombosis?

RATIONALE AND OBJECTIVES

The purpose of this study was to examine transcatheter aspiration as an adjunct to local thrombolysis in a porcine model of acute deep venous thrombosis (DVT).

MATERIALS AND METHODS

DVT was induced in both hind limbs of five pigs. Thirty minutes later, bilateral thrombolysis was performed by using infusion guidewires placed coaxially through occlusion balloon catheters. A temporary venous filter was then placed in the inferior vena cava. The balloon catheters and infusion wire were removed, a 14-F sheath was placed on the right side, and aspiration of residual thrombi was attempted with 8- and 6-F catheters. At autopsy, the mass of any thrombus in the iliofemoral veins was measured, and residual thrombosis in the venous tributaries was graded at four sites. Thromboemboli in the inferior vena cava and the pulmonary circulation were also collected and weighed.

RESULTS

With aspiration and lysis, the iliofemoral veins were cleared of thrombus in three of five limbs; from the remaining two, only 0.09 and 0.15 g of thrombus were harvested. Except for the deep femoral vein in two legs, tributaries were free of thrombus. After thrombolysis alone, thrombi ranged in mass from 0.54 to 1.14 g (median, 0.70 g). Some thrombi were observed in most tributaries. One or two small emboli were found trapped by the caval filter and in the pulmonary circulation in four and three pigs, respectively.

CONCLUSION

The primary axial veins and their tributaries can be rapidly cleared of thrombus by using thrombolysis with transcatheter aspiration, but this procedure is associated with the risk of pulmonary embolism.

Retrospective comparison of the Amplatz thrombectomy device with modified pulse-spray pharmacomechanical thrombolysis in the treatment of thrombosed hemodialysis access grafts

PURPOSE

To retrospectively evaluate the Amplatz thrombectomy device (ATD) in the treatment of thrombosed hemodialysis grafts and compare it with modified pulse-spray pharmacomechanical thrombolysis (PPT).

MATERIALS AND METHODS

During a 4-month period, 79 patients presented with 126 episodes of graft occlusion. Percutaneous recanalization was performed by using the ATD (n = 57) or the modified PPT technique (n = 69). Evaluation included the technical success, complications, and primary patency rates.

RESULTS

Technical success was achieved in 93% (53 to 57) of the cases treated with the ATD and in 96% (66 of 69) of the cases treated with modified PPT (P = .70). Complications occurred in 6% (four of 69) of modified PPT procedures and 16% (nine of 57) of ATD procedures. This difference was not statistically significant (P = .08); however, there were significantly more local complications in the ATD group (P = .04). The primary patency rates at 30, 90, and 180 days were 65% and 65%, 36% and 50%, and 26% and 33% for modified PPT and ATD, respectively. Survival curves were found not to differ significantly (P = .49).

CONCLUSION

The ATD and modified PPT were similarly successful in the recanalization of thrombosed hemodialysis access grafts and achieved comparable primary patency rates. The higher rate of local complications and technical difficulties encountered with use of the 8-F ATD limit its usefulness for this indication.

Comparison of the angiojet rheolytic catheter to surgical thrombectomy for the treatment of thrombosed hemodialysis grafts. Peripheral AngioJet Clinical Trial

PURPOSE

To compare the clinical effectiveness of the AngioJet F105 rheolytic catheter to that of surgical thrombectomy for the treatment of thrombosed hemodialysis grafts.

MATERIALS AND METHODS

This was a multicenter, prospective, randomized trial comparing technical success, primary patency, and complication rates. A total of 153 patients were enrolled: 82 patients in the AngioJet group and 71 patients in the surgical thrombectomy group. Patient follow-up was performed 24-48 hours, 1 month, and 6 months after the procedures.

RESULTS

Technical success, as defined by the patient's ability to undergo hemodialysis treatment, was 73.2% for the AngioJet group and 78.8% for the surgical thrombectomy group (P = .41). The primary patency rates of the AngioJet group were 32%, 21%, and 15% at 1, 2, and 3 months, respectively. The primary patency rates for the surgical group were 41%, 32%, and 26% at 1, 2, and 3 months, respectively. This difference approached statistical significance (P = .053). The groups had similar complication rates-14.6% in the AngioJet group and 14.1% in the surgery group-although the surgery group had more major complications (11.3%). In the AngioJet group, there was a transient increase in plasma-free hemoglobin, which normalized within 24-48 hours.

CONCLUSIONS

The AngioJet F105 catheter provides similar clinical results when compared to surgical thrombectomy for the treatment of thrombosed hemodialysis grafts. The difference in patency rates between these two techniques approached statistical significance. In addition, results of both thrombectomy methods were inferior to those suggested by the Dialysis Outcomes Quality Initiative guidelines.