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

Comparison of pharmacological thrombolysis with mechanical thrombectomy in thrombosed arteriovenous fistulas and grafts: a systemic review and meta-analysis

AIM

To compare the effectiveness and safety of pharmacological thrombolysis and mechanical thrombectomy.

MATERIAL AND METHODS

This review was conducted in accordance with the PRISMA guidelines. Pooled proportions and subgroup analysis were calculated for primary and secondary patency rates, technical success, clinical success, major and minor complications rates.

RESULTS

This systematic review identified a total of 6,492 studies of which 17 studies were included for analysis. A total of 1,089 patients comprising 451 (41.4 %) and 638 (58.6 %) patients who underwent thrombolysis and mechanical thrombectomy procedures, respectively, were analysed. No significant differences were observed between thrombolysis and mechanical thrombectomy procedures in terms of technical success, clinical success, major and minor complications rates, primary and secondary patency rates; however, subgroup analysis of overall arteriovenous fistulas (AVFs) and arteriovenous grafts (AVGs) demonstrated a significantly higher rate of major complications within the AVF group (p=0.0248).

CONCLUSION

The present meta-analysis suggests that pharmacological thrombolysis and mechanical thrombectomy procedures are similarly effective and safe; however, AVFs are subject to higher major complications compared to AVGs.

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.

Direct Percutaneous Thrombolysis (DPT): A novel method of salvaging Thrombosed Native Arteriovenous Fistula

INTRODUCTION

Thrombosed arteriovenous fistulas (AVFs) are either treated by thrombectomy or pharmaco-mechanical thrombolysis with or without percutaneous balloon angioplasty. In this study, we have described an effective and economical technique of salvaging these fistulae using a 20-22-gauge spinal needle and urokinase and have named it direct percutaneous thrombolysis (DPT).

MATERIALS AND METHOD

This prospective study comprised of 148 patients out of which 120 patients presented with AVF thrombosis and were divided into two groups; those with no obvious stenosis on ultrasound (n = 38) and second with venous stenosis (n = 82). Remaining 28 patients developed thrombosis post angioplasty for venous stenosis. Percutaneous injection of urokinase into the thrombus was done under ultrasound guidance, followed by balloon angioplasty if there was associated stenosis.

RESULTS

In 38 patients who didn't have any stenosis, 32 AVFs were successfully thrombolysed by DPT, with technical success of 84.2%. Remaining six patients required angioplasty because of chronic nature of clot. In 82 patients who had venous stenosis, 80 cases were treated successfully by DPT followed by angioplasty with technical success of 97.5%. In third group (n = 28), who developed thrombosis post angioplasty, 100% success rate was noted. The mean length of thrombus was 31.4 ± 4.6 mm and mean diameter of thrombosed vein was 10.5 ± 1.2 mm. There were no major complications encountered during the procedure. Minor complications were seen in 19 patients which included prolonged oozing from puncture site and local hematoma formation.

CONCLUSION

Ultrasound guided DPT with urokinase is a safe and economical option for salvaging thrombosed AVF without vascular stenosis that does not need angioplasty.

Arteriovenous fistulas for hemodialysis: Brief review and current problems

The number of people worldwide living with end-stage renal disease is increasing. Arteriovenous fistulas are the preferred method of vascular access in patients who will require hemodialysis. As the number of patients with arteriovenous fistulas grows, the role of physicians who intervene who maintain and salvage these fistulas will grow in importance. This review aims to familiarize practitioners with the rationale for arteriovenous fistula creation, the detection of fistula dysfunction, and the state of the art on fistula maintenance and preservation. Current controversies are briefly reviewed.

[Complications of permanent vascular access for haemodialysis]

Permanent vascular access is the basis of renal replacement therapy by the method of programmed haemodialysis, on whose stable functioning depends the life of patients with end-stage renal disease. At the present time, there is significant deficit of scientific and methodological Russian-language literature on this problem, with no Russian consensus documents concerned. This article is a review of the contemporary world literature dedicated to the problem of permanent vascular access, including currently in force European (2018) and North American (2019) guidelines for good clinical practice, also discussing the problems of strategy and tactics of creating a permanent vascular access, monitoring its dysfunction, pathophysiology of functioning of arteriovenous fistulas. Presented herein are unified approaches to diagnosis and treatment of thrombolytic and haemorrhagic complications associated with the access, as well as local infectious and non-infectious complications. Special attention is paid to indications for the operation and rational therapeutic decision-making.

Comparative efficacy and safety of local and peripheral venous thrombolytic therapy with urokinase for thrombosed hemodialysis arteriovenous fistulas

Arteriovenous fistula (AVF) thrombosis is a common complication in patients undergoing hemodialysis, and early intervention is required. Urokinase has been used as a thrombolytic agent for declotting the thrombosed access. However, the optimal route for infusing urokinase remains to be determined. In the present retrospective observational study, 49 patients who underwent local venous infusion and 57 patients with peripheral venous infusion of urokinase were included. A urokinase dosage of 300,000 U was administered until successful thrombolysis, which was a maximum of three times. Age, sex, period of dialysis, time of AVF placement, systolic and diastolic blood pressure and thrombus age were similar between the two groups. The efficacy of urokinase infusion via the two routes in resolving thrombosed AVFs, defined as successful fibrinolysis, and the safety, defined as the number of bleeding events, was compared. The cumulative thrombolysis success rate following three sessions of thrombolytic therapy in the local venous thrombolysis group was higher compared with that in the peripheral venous thrombolysis group (85.7 vs. 68.4%; P=0.04). The local thrombolysis group exhibited less ecchymosis (4.1 vs. 14.0%; P=0.07), epistaxis (2.0 vs. 10.5%; P=0.08) and gingival bleeding (4.1 vs. 19.3%; P=0.02) events compared with the peripheral thrombolysis group. Further analyses demonstrated that systolic [odds ratio (OR)=1.10; 95% confidence interval (CI), 1.03-1.17; P<0.01] and diastolic (OR=1.08; 95% CI, 1.02-1.14; P<0.05) blood pressure were protective factors, whereas thrombus age (OR=0.91; 95% CI, 0.84-0.99; P<0.05) was a risk factor for thrombolysis success among patients who underwent local thrombolytic therapy. Overall, the results suggest that local venous infusion of urokinase is superior to peripheral venous infusion for the treatment of patients with thrombosed fistulas.

Spanish Clinical Guidelines on Vascular Access for Haemodialysis

Vascular access for haemodialysis is key in renal patients both due to its associated morbidity and mortality and due to its impact on quality of life. The process, from the creation and maintenance of vascular access to the treatment of its complications, represents a challenge when it comes to decision-making, due to the complexity of the existing disease and the diversity of the specialities involved. With a view to finding a common approach, the Spanish Multidisciplinary Group on Vascular Access (GEMAV), which includes experts from the five scientific societies involved (nephrology [S.E.N.], vascular surgery [SEACV], vascular and interventional radiology [SERAM-SERVEI], infectious diseases [SEIMC] and nephrology nursing [SEDEN]), along with the methodological support of the Cochrane Center, has updated the Guidelines on Vascular Access for Haemodialysis, published in 2005. These guidelines maintain a similar structure, in that they review the evidence without compromising the educational aspects. However, on one hand, they provide an update to methodology development following the guidelines of the GRADE system in order to translate this systematic review of evidence into recommendations that facilitate decision-making in routine clinical practice, and, on the other hand, the guidelines establish quality indicators which make it possible to monitor the quality of healthcare.

Comparison between open and pharmacomechanical repair of acutely thrombosed arteriovenous hemodialysis fistulae within a decade

INTRODUCTION

Different declotting techniques are available for acutely thrombosed arteriovenous hemodialysis fistulae (AVF). The aim of this single-center study was to compare immediate and follow-up results between surgical repair and a modified interventional lyse-and-wait technique characterized by prolonged local reaction times of recombinant tissue-plasminogen activator (rtPA).

MATERIALS AND METHODS

We retrospectively analyzed medical records of 110 consecutively treated patients between the years 2003 and 2013. All patients were on hemodialysis (HD) and suffered from an acutely thrombosed AVF. The treatment standards changed in the course of time, wherefore we compared 2 groups: the open repair (OR) (N = 50) and the endovascular repair (ER) group (N = 60).

FINDINGS

We found no significant differences in success rates (OR 92%/ER 96.7%; P = 0.28), immediate failures (IFs) (OR 8%/ER 10%; P = 0.71), and temporary catheter placements (TCPs) (OR 10%/ER 6.7%; P = 0.52). Furthermore, there were no differences in cumulative primary patency rates (P = 0.42) and secondary patency rates (P = 0.97).The infection rate was significantly increased after OR (8%) compared to ER (0%); P = 0.026. The hospital stay in days was shorter after ER (5.2 ±2.8) vs. OR (9.0 ± 3.5); P < 0.001.

CONCLUSION

The modified lyse-and-wait technique with prolonged local reaction times is a successful alternative to surgical repair for acutely thrombosed AVF. Clear benefits are less infections and significant shorter hospital stays after ER. However, OR remains the preferred treatment for aneurysms and anastomotic stenoses.

Novel use of the ClariVein® catheter for pharmacomechanical thrombolysis of thrombosed hemodialysis grafts: a case series

INTRODUCTION

The aim of this prospectively collected case series is to demonstrate a novel technique of using the ClariVein® catheter for pharmacomechanical thrombolysis of thrombosed hemodialysis grafts.

METHODS

The analysis comprised 11 procedures in 9 patients from 1 July to 31 December 2016 in which the ClariVein catheter was used in combination with urokinase. Demographic data, procedural data, technical and clinical success rates, and complications were evaluated. The primary and secondary patency rates at 1 and 3 months were also analyzed.

RESULTS

In the 11 procedures performed, the technical and clinical success was 100%. The mean procedural time was 66.8 minutes (range 50-90 minutes), and the mean amount of urokinase administered was 87,000 units. The primary unassisted patency rates at 1 and 3 months were 81.8% and 63.6%, respectively. The secondary patency rates at 1 and 3 months were 90.9% and 81.8%, respectively. Perforation occurred after balloon angioplasty in 1 (9.1%) of the 11 procedures, for which covered stenting was performed. No major complications occurred.

CONCLUSIONS

The combination use of the ClariVein catheter with urokinase for pharmacomechanical thrombolysis in thrombosed hemodialysis grafts is a feasible and safe method that can be performed in a relatively short duration. Our early results have shown 100% technical and clinical success. This case series serves as a platform for an upcoming prospective study to further evaluate this method.

Benefits of Long Versus Short Thrombolysis Times for Acutely Thrombosed Hemodialysis Native Fistulas

INTRODUCTION

Local thrombolysis with a time of exposure to recombinant tissue plasminogen activator of 15 to 150 minutes is commonly used to declot acutely thrombosed hemodialysis fistulas. The duration of thrombolysis for the restoration of arteriovenous blood flow remains controversial. The aim of this study was to investigate the outcomes of long thrombolysis treatment (LTT, 3 hours or more) and short thrombolysis treatment (STT, less than 3 hours) in our institution.

METHODS

We retrospectively analyzed 86 interventional declotting procedures (28 STT and 58 LTT) applied to 86 acutely thrombosed hemodialysis fistulas. The intervention time (IT) following thrombolysis (from the initial fistulography to the end of the angioplasty maneuvers), the time of day of the intervention (ie, during working hours vs off-hours), and the need for temporary catheter placement (TCP) were assessed. Success was defined as complete access recanalization, and major adverse events were defined as ischemia, bleeding, and access rupture.

RESULTS

The ITs were reduced after LTT (63.3 [9.3] minutes) compared to STT (106.7 [24.7], P = .01), but there was no difference in success rate (85.7% STT, 89.7% LTT, P = .722). While all (100%, 58/58) of the angioplasty maneuvers after LTT were performed during regular working hours, 75% (21/28) of those following STT were managed during off-hours ( P < .001). Despite the longer treatment, the need for TCP was not increased after LTT (10.7%) compared to STT (12.1%, P = .515), and the major complication rate was reduced (3.4% after LTT and 28.6% after STT, P = .004).

CONCLUSION

Long thrombolysis treatment results in shorter and less complicated percutaneous stenosis treatments during regular working hours. Despite the LTT of up to 25 hours until access for dialysis was achieved, no increase in the risks of TCP or major adverse events were observed following LTT.

Time-extended local rtPA infiltration for acutely thrombosed hemodialysis fistulas

INTRODUCTION

This study describes results of a modified local thrombolysis technique for acutely thrombosed hemodialysis (HD) arteriovenous fistulas (AVF), which is characterized by prolonged recombinant tissue plasminogen activator (rtPA) local exposure times. Contrary to the standard lyse- and- wait (L&W) technique with local reaction times of 20-40 minutes, the modified protocol allows timing of challenging angioplasty maneuvers to the next regular working day.

METHODS

From February 2009 to April 2014, 84 patients on HD presented with 152 acutely thrombosed AVF. They proceeded to local thrombolysis including a single shot infiltration of rtPA, local reaction time up to 40 hours and finally percutaneous stenosis angioplasty. Success rates, major adverse events and need for temporary catheter placements (TCP) were retrospectively analyzed.

FINDINGS

The local thrombolysis time after single shot infiltration was 18.6 ± 6.2 (range 2-40) hours. Mean rtPA- dosage was 2.7 mg ± 1.2. The overall success rate was 89.5% and the major complication rate was 3.3%, whereas TCP was necessary in 12.5%. The PP/SP at 1, 3, 6, 12, 18, and 24 month were 86% ± 3%/95% ± 2%, 68% ± 4%/92% ± 2%, 43% ± 4%/90% ± 2%, 28% ± 4%/82% ± 3%, 12% ± 3%/82% ± 3%, 7% ± 2%/63% ± 4%, respectively.

CONCLUSION

The modified L&W technique with prolonged local rtPA reaction times is a safe and effective declotting procedure. The need for TCP was not increased and therefore comparable to the standard technique.

Advances in Endovascular Techniques to Treat Failing and Failed Hemodialysis Access

During the decade since JEVT was inaugurated, we have witnessed the growing application of endovascular techniques for arteriovenous (AV) access in parallel with the evolution of endovascular therapy for arterial pathology. To date, few if any technologies have compared with balloon angioplasty for treating venous anastomotic stenosis, the most common cause of access failure. Only one device, which incorporates the principles of access graft design and self-expanding stent technology, has been uniquely conceived for this pathology. The encapsulated polytetrafluoroethylene stent-graft has achieved reasonable preliminary results, but randomized data is forthcoming. Technology to clear the clot from a thrombosed graft continues to evolve, but will never be as cost-effective as simple balloon thrombectomy. However, the pressure placed on providers to perform all percutaneous interventions and move away from open techniques continues to fuel interest in this component of treatment. Finally, the pursuit of a completely percutaneous AV access continues. As with endovascular procedures in general, whether or not the procedure is cost-effective or time-consuming seems to take a back seat to the all-percutaneous approach that so many seem to converge upon. Moreover, as most autogenous fistulas and AV grafts can be created with minimal incisions under local anesthesia, the pursuit of a completely percutaneous access system seems more like an academic exercise than a practical application of technology. We must try and avoid the tendency to “minimize invasiveness” with technology that is maximally intensive (and expensive), such as limiting ourselves to only percutaneous methods. Given the increasing pressure to have an all autogenous access program, current techniques that apply well in prosthetic grafts will need to be modified to accommodate the different biology of a native fistula. Clearly, the enlarging end-stage renal disease population will continue to provide endovascular specialists with clinically challenging problems requiring new and revolutionary technology.

The use of tissue plasminogen activator as continuous infusion into an arteriovenous hemodialysis access in the hemodialysis unit: a case series

BACKGROUND

Thrombolytics such as tissue plasminogen activator are often used by interventional radiologists in the radiology suite to salvage thrombosed hemodialysis arteriovenous fistulae. Thrombolytics are also commonly used in dialysis facilities as a dialysis catheter lock solution or as an infusion into a dialysis catheter when dysfunctional. However, the use of tissue plasminogen activator as a continuous infusion into an arteriovenous fistula in the dialysis facility to treat clot burden is not commonly done.

OBJECTIVE

The aim of our case series is to demonstrate the successful use of tissue plasminogen activator to decrease clot burden in an arteriovenous fistula in the dialysis unit.

DESIGN

Observational case series.

SETTING

An outpatient dialysis facility in a tertiary care hospital.

PATIENTS

Three non- consecutive patients were diagnosed with an acute thrombosed arteriovenous fistula either on physical exam or by imaging.

MEASUREMENTS

A thrombosed fistula as well as successful resolution of clot was illustrated by either physical exam, fistulogram or ultrasound. A functioning fistula demonstrated successful continuation of dialysis and adequate access flow measurements in follow up.

METHOD

This is a case series that describes the technique of using an infusion of tissue plasminogen activator into an arteriovenous fistula on the dialysis unit by vascular access nurses to treat or diminish clot burden.

RESULTS

We have described three separate cases where treatments with tissue plasminogen activator infusions on the dialysis unit resulted in objective evidence of decrease in clot burden on ultrasound or fistulogram.

LIMITATIONS

The small numbers of our case series requires that the results need to be verified in a larger study. Inclusion and exclusion criteria need to be defined before widespread application of this technique.

CONCLUSIONS

To our knowledge this small case series is the first to describe the procedure whereby low dose tissue plasminogen activator is directly infused into the fistula by the vascular access nurse in the dialysis unit during dialysis and not in the interventional suite. This provides additional information to the existing literature that there is an alternative option for dialysis units to diminish clot burden until a more permanent solution is established through angioplasty.

Clinical outcome of percutaneous thrombectomy of dialysis access thrombosis by an interventional nephrologist

Background

Traditionally, the treatment of a thrombosed dialysis access in hemodialysis patients in Korea has been primarily performed by vascular surgeons and interventional radiologists. The objective of this study was to evaluate the outcome of percutaneous thrombectomy procedures performed by an interventional nephrologist.

Methods

From October 2010 to May 2014, 75 consecutive percutaneous thrombectomies were performed on 42 patients treated with maintenance hemodialysis. All percutaneous thrombectomy procedures were performed by an interventional nephrologist in a single hospital in Jeju, Korea. The thrombosed arteriovenous graft and arteriovenous fistula were declotted by thromboaspiration mechanical thrombectomy or pharmacomechanical thrombolysis. Kaplan–Meier survival analysis was performed to analyze the primary and secondary patency after the initial successful thrombectomy. Success and complication rates were identified and compared with the recommendations of the Kidney Disease Dialysis Outcomes Quality Initiative (KDOQI) guideline.

Results

The overall clinical success rate was 89.3% (67/75). In the successful cases, the postintervention primary (unassisted) patency rates at 30 days, 90 days, and 180 days were 79.9%, 56.6%, and 25.6%, respectively. The secondary patency rates at 30 days, 90 days, and 180 days were 92.2%, 85.7%, and 83.7%, respectively. There were no major complications, and all complications were treated successfully during the procedure.

Conclusion

The clinical success rate and primary patency rate at 3 months exceeded the recommendations of the KDOQI guideline, and were comparable to that of other reports. Percutaneous thrombectomy by an interventional nephrologist was safe and effective.

Thromboaspiration of arteriovenous hemodialysis graft thrombosis using Desilets-Hoffman sheath: single-center experience

PURPOSE

The purpose of this study was to evaluate the feasibility, efficacy and safety of percutaneous thromboaspiration with a 7F Desilets-Hoffman sheath compared with previously established percutaneous mechanical thrombectomy techniques in occluded hemodialysis grafts.

MATERIALS AND METHODS

One thousand three hundred five patients (767 women, 538 men; mean age, 61.04±13.09 years; mean graft age, 36.64±30.80 mo) with 2,531 episodes of hemodialysis graft thrombosis underwent percutaneous thromboaspiration with a 7F Desilets-Hoffman sheath using criss-cross or apex puncture technique. Technical success rate, procedure time, complications and patency rates were analyzed.

RESULTS

Technical success was achieved in 2,426 of 2,531 procedures (95.9%). Average procedure time of the intervention was 42.87±22.77 minutes. Primary patency rate was 61.9% at 3 mo, 41.2% at 6 mo and 19.6% at 1 year. Major complications occurred in 4.1% of cases (23 graft outflow rupture; 68 arterial emboli; 1 arterial dissection; 3 symptomatic pulmonary embolism; 1 stent migration) and minor complications occurred in 7.7% of cases (196 cases). These results were comparable to previously reported mechanical thrombectomy techniques in occluded hemodialysis grafts.

CONCLUSIONS

Percutaneous thromboaspiration of occluded hemodialysis grafts with a Desilets-Hoffman Sheath is an effective and safe method.

Effect of the time to intervention on the outcome of thrombosed dialysis access grafts managed percutaneously

PURPOSE

We aimed to investigate the effect of the time interval from the clinical presentation of a thrombosed dialysis access graft to intervention on procedure success.

MATERIALS AND METHODS

Records from two academic institutions for patients who underwent percutaneous thrombectomy of occluded surgical hemodialysis graft access sites in interventional radiology from 2006 to 2011 were reviewed retrospectively. The following data were recorded: gender, age, time and date of the initial request for a thrombectomy and the procedure, age of the surgical access, angiographic outcome, and clinical outcome (successful or unsuccessful postinterventional dialysis). Univariate and multivariate logistic regression were used to evaluate whether the time to intervention significantly affected the study endpoint.

RESULTS

In total, 268 percutaneous thrombectomies were performed in 139 patients. Of these 224 (83.5%) were categorized as successful and 44 (16.4%) as unsuccessful. The time to intervention was 19.9±30.1 vs. 22±35 hours for successful and unsuccessful procedures, respectively. The difference between the two was not significant, and there were also no significant differences in covariate distributions between successful and unsuccessful outcomes.

CONCLUSION

During the first 72 hours following clinical presentation of a thrombosed dialysis access graft, time to intervention may be considered independent of procedure outcome.

In-center thrombolysis for clotted AV access: a cohort review

Thrombosis is the leading cause of arteriovenous (AV) access failure for hemodialysis patients requiring frequent interventions. We describe a novel approach to the lyse-and-wait technique in thrombosed AV access using nurse-administered thrombolytics in a hospital-based hemodialysis unit. All patients at a single-center, large, urban, tertiary care hospital, who underwent in-center thrombolysis via alteplase instilled directly into a thrombosed AV access by inpatient hemodialysis unit staff between January 1, 2003 and December 31, 2007, were eligible. Included subjects were at least 18 years old and did not have known or suspected infection or trauma to the AV access site. Primary outcome measure was successful thrombolysis defined as hemodialysis performed immediately or after the interventional radiology (IR) procedure. Adverse events related to the procedure were collected. A total of 321 procedures, performed on 145 subjects (77 (53%) male, 68 (47%) female) remained for analysis. Successful instillation occurred in 317 of 321 procedures (98.8%). Successful thrombolysis occurred in 237 of 321 procedures (73.8%). Adverse events (8 major and 10 minor) occurred in 18 procedures, yielding a complication rate of 5.6%. In-center thrombolysis with alteplase administration by hemodialysis unit nursing staff under physician supervision is safe and effective with an adverse outcome rate similar to the literature. Thus, this modified lyse-and-wait protocol can be adopted with appropriate IR and surgical backup in place.

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.

The radiological management of the thrombosed arteriovenous dialysis fistula

Patent vascular access is a prerequisite for adequate haemodialysis, and is a major determinant of quality of life and long-term survival of patients with end-stage renal disease. Autogenous haemodialysis fistulas (AVFs) have demonstrated superior clinical outcome when compared to synthetic grafts, but both types of access remain susceptible to venous stenoses, and consequent thrombotic occlusion. Recent publications have reported primary patency rates of up to 100% following percutaneous de-clotting of AVFs incorporating techniques such as pharmacological thrombolysis, mechanical thrombectomy, and thrombo-aspiration. Endovascular management also provides information regarding the underlying cause of access thrombosis, with option to treat. Consequently, there has been a paradigm shift in the management of fistula thrombosis, with interventional radiology assuming a lead role in initial salvage procedures. This article will attempt to provide the reader with an insight into the multiple radiological techniques that can be employed to salvage a thrombosed AVF based on current published literature.

Thrombolysis with alteplase: a non-invasive treatment for occluded arteriovenous fistulas and grafts

Thrombolysis with recombinant tissue type plasminogen activator (t-PA) has been successfully used in occluded arteriovenous (AV) hemodialysis grafts and tunneled catheters, especially as an adjunctive regimen to invasive or semi-invasive procedures. We performed a retrospective study to evaluate the effectiveness and outcomes of thrombolysis with t-PA in occluded AV hemodialysis accesses. We used low doses of t-PA in 40 cases of thrombosed AV fistulas and grafts. Primary success was noted in 55% of the cases ensuring patency rates of 30 and 90 days at 90.9 and 69.8%, respectively. Inflammation (increased C-reactive protein concentration) and shorter functioning time of AV access were independently associated with primary outcome, whereas there was no difference in outcome between AV fistulas or grafts. No major complications were noted. We conclude that the use of t-PA is a safe and easy treatment for clotted AV accesses that can be applied in an outpatient setting.

Cardiac Arrest Following Massive Pulmonary Embolism During Mechanical Declotting of Thrombosed Hemodialysis Fistula: Successful Resuscitation With tPA

Percutaneous declotting of a thrombosed fistula or graft is standard of care and is a safe procedure. Subclinical pulmonary embolism (PE) during this procedure occurs commonly, but symptomatic PE is extremely rare. The authors report a case of declotting-associated massive PE with cardiopulmonary arrest and successful resuscitation. The patient developed a new right-axis deviation and right-bundle branch block. Diagnosis of PE was confirmed with a computed tomography (CT) angiogram, and the patient received tissue plasminogen activator (tPA) and heparin. She required norepinephrine and dobutamine temporarily and was subsequently extubated successfully. Massive PE is a very rare complication of this procedure. Given the grave outcome, the clinical signs and symptoms should be recognized immediately and treatment instituted early.

Efficacy of ProLumen in Percutaneous Thrombectomy of Clotted Dialysis Access: A Single-Center Prospective Study

Purpose

To prospectively evaluate the efficacy of the ProLumen thrombectomy device for declot of dialysis access.

Methods

16 women and 4 men suffering from end-stage renal disease (ESRD) dependent on hemodialysis (mean age, 66.4 years) and presenting with thrombosed dialysis access were enrolled form October 2005 through February 2006. Sixteen patients had synthetic grafts and 4 had native fistulas. Mean age of access was 24.65 months (range, 2 to 96 months). A history of previous intervention was noted for seven patients (6 percutaneous, 1 surgical).

Results

A mean of 2.7 passes of the ProLumen device were required for the venous limb (range, 1 to 6) and 2.35 passes for the arterial limb (range, 0 to 5). Average procedure time was 48 minutes (range 32–81 minutes). Adjunctive thrombectomy devices were utilized in 5 cases. Good angiographic and clinical results were reported in 19 patients; one patient had a poor result. Dialysis flow rate prior to thrombosis was 425 mL/min (range, 300 to 550). The mean post-thrombectomy flow rate was 380 mL/min (range, 200 to 480; n=19). “Ease of use” of Pro Lumen thrombectomy device was rated good in 17 patients. Maneuverability was good in 14 patients and clot removal around the opposite sheath was rated as good in 18 patients.

Conclusions

ProLumen is effective in thrombectomy of dialysis access. The device is easy to use, and effectively removes clot around the opposite sheath.

ASDIN Original Investigation: Successful Treatment of the Chronically Thrombosed Dialysis Access Graft: Resuscitation of Dead Grafts

The most common contributing cause of thrombosis of an arteriovenous graft (AVG) in the hemodialysis patient is the presence of venous stenosis. In the face of a recovery of renal function either spontaneously or as a result of renal transplantation, an AVG commonly thromboses. In cases in which the AVG was recently placed, it is unlikely to have had a significant anatomic lesion at the time function was lost. Even though the access that has been left untreated has become a "dead" AVG, it offers an opportunity for "resuscitation." Thirteen cases that met the specific criteria of being placed only a short period of time prior to thrombosis (3 weeks to 6 months), thrombosing after a return of renal function and having been left untreated (3 months to 8 years) were attempted over a 12 year period. The technique applied was modified from the one routinely used based on the presumption that very little or no thrombus was present. The effort was met with success in 8 of the 13 patients. After being opened, the AVG appeared to follow the same patency pattern as other AVGs. It appears that attempting restoration of function of an AVG meeting these criteria may be indicated. Limited experience using this approach in AVGs that do not meet these specific criteria has uniformly met with failure.

Single-center experience with the Arrow-Trerotola Percutaneous Thrombectomy Device in the management of thrombosed native dialysis fistulas

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.

Vein wall dissection: a rare puncture-related complication of brachiocephalic fistula. Gray-scale and color Doppler sonographic findings

We describe a case of brachiocephalic fistula vein wall dissection (VWD) occurring in a 36-year-old female hemodialysis patient. Unlike subcutaneous or subfascial infiltrations for which the mechanism is blood extravasation, VWD seems to be due to disruption of the fistula vein layers caused by misplacement of the outflow (venous) needle bevel. In this setting, the pressure of the dialysis blood pump acts as the driving force of the dissecting column, extending it proximally. Gray-scale and color Doppler sonography proved to be very useful in the differential diagnosis of VWD, particularly with thrombosis of the fistula. Sonography also helped us decide when to resume cannulations.

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.

Advances in endovascular techniques to treat failing and failed hemodialysis access

During the decade since JEVT was inaugurated, we have witnessed the growing application of endovascular techniques for arteriovenous (AV) access in parallel with the evolution of endovascular therapy for arterial pathology. To date, few if any technologies have compared with balloon angioplasty for treating venous anastomotic stenosis, the most common cause of access failure. Only one device, which incorporates the principles of access graft design and self-expanding stent technology, has been uniquely conceived for this pathology. The encapsulated polytetrafluoroethylene stent-graft has achieved reasonable preliminary results, but randomized data is forthcoming. Technology to clear the clot from a thrombosed graft continues to evolve, but will never be as cost-effective as simple balloon thrombectomy. However, the pressure placed on providers to perform all percutaneous interventions and move away from open techniques continues to fuel interest in this component of treatment. Finally, the pursuit of a completely percutaneous AV access continues. As with endovascular procedures in general, whether or not the procedure is cost-effective or time-consuming seems to take a back seat to the all-percutaneous approach that so many seem to converge upon. Moreover, as most autogenous fistulas and AV grafts can be created with minimal incisions under local anesthesia, the pursuit of a completely percutaneous access system seems more like an academic exercise than a practical application of technology. We must try and avoid the tendency to "minimize invasiveness" with technology that is maximally intensive (and expensive), such as limiting ourselves to only percutaneous methods. Given the increasing pressure to have an all autogenous access program, current techniques that apply well in prosthetic grafts will need to be modified to accommodate the different biology of a native fistula. Clearly, the enlarging end-stage renal disease population will continue to provide endovascular specialists with clinically challenging problems requiring new and revolutionary technology.

Cross-Species Pharmacologic Evaluation of Plasmin as a Direct-Acting Thrombolytic Agent: Ex Vivo Evaluation for Large Animal Model Development

PURPOSE

Human plasma-derived plasmin has been developed for the treatment of thrombosed hemodialysis arteriovenous grafts and vascular occlusive diseases. To further investigate this drug in large animal models and derive preliminary dosing estimates, the authors compared plasmin's relative lytic potential in four species, including man. The goal was to find which species' whole blood clots best compared to human clots in terms of lysis with plasmin. The results from these studies will serve to guide species selection for large animal experimentation.

MATERIALS AND METHODS

Clotted blood from human, pig, sheep, and bovine subjects were treated with saline solution control, plasmin, or tissue plasminogen activator. Electron microscopy (EM) techniques were used to investigate the effects of clot size and fragmentation on plasmin lysis, the effects of intrathrombic infusion by injection of plasmin directly into whole blood clots, and species fibrin structural differences.

RESULTS

Under static conditions, plasmin efficiently lysed clots from all species studied at an optimal dose of 4-5 mg per 4-5 g of clot. With fragmented human clots, plasmin (5 mg)-induced lysis was 80% +/- 2% at 60 minutes. Porcine clots were more resistant to plasmin lysis compared with human, ovine, and bovine clots. Percent lysis at 60 minutes with plasmin for ovine clots was 72% +/- 3% (4-mg dose), compared with 50% +/- 4% for porcine clots (5-mg dose; P < .05). EM of porcine clots showed a compact fibrin network that appeared more dense than that in human or sheep clots, which may account for the decreased lytic rate.

CONCLUSIONS

Human plasmin is an effective direct-acting thrombolytic agent that is capable of lysing fibrin from several species. Ex vivo lysis studies were used to investigate the most appropriate large animal model that best approximates plasmin lysis with human clots under certain conditions. It was determined that ovine clots treated with plasmin most closely resemble the lysis observed with human clots.

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.

Management of thrombosed dialysis access: thrombectomy versus thrombolysis

More than 250,000 patients per year with end stage renal disease are maintained on long-term hemodialysis. Because of this large population, hemodialysis access procedures now account for a large percentage of operative interventions in the United States. Prosthetic arteriovenous access thrombosis is a frequent complication that occurs at a rate of 0.5 to 0.8 episodes per year and is a major source of hospital admissions, increasing hospital costs, patient morbidity, and physician frustration. Thrombosed grafts often require rescue procedures to extend the life of the graft and make the most use of the limited available access sites. Such salvage procedures of thrombosed prosthetic dialysis shunts may be performed with either conventional surgical or endovascular techniques. Many techniques for declotting have been used, including open surgical thrombectomy, percutaneous pharmacologic or mechanical thrombectomy, and pharmacomechanical techniques. Despite the various treatment options, no individual declotting modality has proven itself superior. Long-term patencies after a single revascularization procedure are meager, with a median of less than 90 days. This article will review prosthetic hemodialysis access graft declotting mechanisms and supporting literature.

Percutaneous management of thrombosed dialysis access grafts

This article reviews current concepts in the percutaneous management of thrombosed polytetrafluoroethylene (PTFE) dialysis access grafts. The maintenance of dialysis access grafts remains a challenging task. Graft surveillance is critical in the prevention of graft thrombosis to prolong graft survival. Once a graft is thrombosed, surgical and percutaneous options are available for restoration of flow. There has been an evolution in the percutaneous treatment of thrombosed dialysis access grafts during the last 20 years, with refinement of pharmacomechanical techniques, allowing for safe and efficacious restoration of flow in thrombosed grafts. There has been emergence of alternative thrombolytic agents to urokinase, which was withdrawn from the United States in late 1998 and recently reintroduced. These alternative thrombolytic agents have similar outcomes compared with urokinase, with the additional advantage of being less expensive. In addition, several mechanical devices, which were popular briefly when urokinase was unavailable, are available currently for use within grafts, with similar success, although their prices have limited widespread use.

Complications of percutaneous treatment of thrombosed hemodialysis access grafts

Percutaneous catheter-based thrombolysis is commonly used in association with angioplasty to treat thrombosed hemodialysis arteriovenous grafts. Although major complications of these percutaneous procedures are relatively uncommon, they can result in several potentially serious complications, including pulmonary embolism, cerebral embolism, arterial embolism, bleeding with perigraft hematoma or hemorrhage, and vein rupture. This article reviews the epidemiology, clinical significance, and management of these complications.

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.