Percutaneous intervention for permanent hemodialysis access: a review

Restoration of Acutely Thrombosed Arterio-Venous Fistulae by rTPA and Percutaneous Angioplasty

Acute thrombosis in native arterio-venous fistulae (AVF) results in considerable patient morbidity. Interventional radiology (IR) comprising thrombolysis and percutaneous transluminal angioplasty (PTA) is well established in the management of thrombosed polytetrafluoroethylene (PTFE) grafts. However its role in thrombosed AVF is uncertain. We looked retrospectively at the role of IR in re-establishing blood flow in acutely thrombosed AVF.

Between 1992–2000, 21 episodes of acutely thrombosed AVF in 15 patients (9 females; age range 29–80yrs) were referred for intervention. All fistulae were being used for haemodialysis at the time. Diagnosis was established by angiography and thrombolysis with recombinant tissue plasminogen activator (rTPA) was attempted in all patients. Discrete stenoses when present (n=12) were then treated with PTA and resistant or recurrent stenoses were managed by stent insertion (n=3). Patients were then heparinised for 24 hours.

Technical success as defined by radiological patency was achieved in 86% cases. Clinical success i.e. the ability to reuse of the fistula for haemodialysis was achieved in 62% of the interventions, where patency rates at 3 and 6 months were 92% and 69% respectively. Five patients had recurrence of thrombosis >3 months after the primary procedure, 3 had successful re-intervention. Minor local bleeding was the only complication.

Our retrospective study shows rTPA and PTA is successful in the management of acutely thrombosed AVF. We advocate the routine use of IR as a valuable technique for prolonging the life of native AVF in patients on maintenance haemodialysis.

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.

Vascular Rupture during Angioplasty of Hemodialysis Graft-Related Stenoses

Purpose

To retrospectively determine the incidence and outcome of angioplasty-induced ruptures that occurred during treatment of hemodialysis graft-related stenoses.

Materials and Methods

During a five year period 1222 patients with dysfunctional or thrombosed polytetrafluoroethylene (PTFE) hemodialysis grafts underwent angioplasty procedures at our institution. Angioplasty-induced vascular ruptures occurred in 24 (2.0%) patients. The locations of these ruptures were: basilic vein (10), venous anastomosis (7), cephalic vein (5), brachial vein (1) and intragraft (1). The mean length of the treated stenoses was 2.4 centimeters.

Results

Manual compression was used to treat the vascular rupture in ten patients. One patient was treated with endovascular balloon tamponade and one patient underwent stenting of the rupture site. Despite the rupture, 15 patients had completion of the angioplasty procedure. In nine patients the procedure was abandoned due to persistent stenosis at the rupture site. There were no major complications as a result of these ruptures. Follow-up was available in ten of these patients. All ten underwent at least one successful hemodialysis treatment. In five of these patients the hemodialysis graft failed within 30 days after the rupture. The mean primary patency following rupture in the ten patients with follow-up was 87.5 days (range 5 – 225 days).

Conclusion

The incidence of angioplasty-induced vascular rupture of hemodialysis-related stenoses is low and despite the injury, the majority (62%) of procedures can be completed. However, in our experience the long-term patency of the vascular access was suboptimal.

Stenoses in the surgically manipulated segment have better angioplasty response compared to the surgically naive segment in fistulas

Purpose

Balloon angioplasty is the standard treatment for dysfunctional hemodialysis fistulas, but angioplasty response of stenotic lesions located in different segments of the dialysis circuit has not been explicitly evaluated. The purpose of this study is to describe the distribution of stenotic lesions in the most common types of arteriovenous fistulas and to investigate the response to balloon angioplasty of stenotic lesions located in various segments of the fistula circuit.

Materials and Methods

This single-center, retrospective study was approved by the Institutional Review Board. A total of 263 fistulograms performed between January, 2014 and June, 2015 were reviewed. Stenotic lesion response to angioplasty was analyzed based on lesion location using a Kaplan-Meier analysis.

Results

Juxta-anastomotic stenoses (48%) were the most common lesions in radiocephalic fistulas, while the cephalic arch (30%) and venous outflow tract (24%) were the most common locations of stenotic lesions in brachiocephalic fistulas and basilic vein transposition fistulas, respectively. Primary patency after balloon angioplasty was significantly higher in lesions located in the venous segments manipulated during surgeries compared to the lesions located in the surgically naive zone (p = 0.001). The 6-month and 12-month primary patency of lesions post-angioplasty in the surgical zone were 76% and 71% compared to 58% and 43% in the surgically naive segments.

Conclusions

The distribution of stenotic lesions differs among each type of fistula. The primary patency of balloon angioplasty of stenotic lesions located in the surgically manipulated venous segment was significantly better than lesions located in the rest of the fistula circuit.

Ultrasound-guided angioplasty for treatment of peripheral stenosis of arteriovenous fistula - a single-center experience

PURPOSE

In patients with end-stage renal disease, arteriovenous fistulas (AVFs) are the access of choice for hemodialysis but are often complicated by stenosis. We present single-center experience of 78 ultrasound-guided angioplasty procedures for treating peripheral stenoses of AVFs.

METHODS

Between January 2013 and November 2015, 78 angioplasties were performed under ultrasound guidance in 53 patients with end-stage renal disease who were referred from dialysis centers with low flow rate, difficult cannulation, increased cannulation site bleeding, immature or thrombosed AVF. Angioplasties were carried out in the presence of a structural lesion in the AVF resulting in at least 50% reduction in vein diameter with a blood flow of <250 mL/min or a peak systolic velocity >300 cm/s. Clinical success, anatomical success and post-intervention primary and secondary patency rates at 6, 12, 18 and 24 months were studied.

RESULTS

In 49/53 patients (92.4%), 74 angioplasty procedures were successfully performed, whereas 4/53 patients (7.6%) had primary failure. A total of 35/49 patients (71.4%) underwent single angioplasty procedure whereas 14/49 patients (28.6%) underwent multiple angioplasty procedures. Post-intervention primary patency rates at 6, 12, 18 and 24 months were 78.6%, 60.2%, 53.8% and 48.9%, respectively. Post-intervention secondary patency rates at 6, 12, 18 and 24 months were 100%, 100%, 95.4% and 89%, respectively. Clinical success and anatomical success was 94.8% and 89.7%, respectively.

CONCLUSIONS

Ultrasound-guided angioplasty is an effective method with good long-term outcomes in selected dialysis patients with peripheral stenosis of AVF.

Evolving roles of radiologists, nephrologists, and surgeons in endovascular hemodialysis access maintenance procedures

PURPOSE

The aim of this study was to evaluate the changing relative roles of radiologists, nephrologists, and surgeons performing endovascular hemodialysis access maintenance procedures.

METHODS

Medicare Physician Supplier Procedure Summary Master Files from 2001 through 2008 were analyzed for procedure codes for hemodialysis access angiography, angioplasty, percutaneous thrombectomy, and open surgical interventions. Using physician specialty code data, component procedure volume for all 3 endovascular services was extracted for radiologists, nephrologists, and surgeons. Percentage changes were calculated for all groups. National trends in percutaneous and open interventions were compared.

RESULTS

Between 2001 and 2008, the total Medicare fee-for-service component procedure volume for dialysis access angiography, angioplasty, and percutaneous thrombectomy increased by 102%, 171%, and 52%, respectively. In 2008, radiologists performed 50% of angiography, 47% of angioplasty, and 46% of declotting procedures, down from 82%, 82%, and 84%, respectively, in 2001. In contrast, nephrologists increased from 4%, 5%, and 4% to 22%, 27%, and 21% of services, and surgeons increased from 7%, 5%, and 4% to 22%, 19%, and 16%. As percutaneous procedures increased in frequency, open surgical interventions declined by 43%.

CONCLUSION

Nationally, endovascular hemodialysis access maintenance procedures have increased as open surgical interventions have declined. Nephrologists and surgeons have both experienced marked relative increases in endovascular procedure volumes as radiologists, previously by far the predominant providers of these services, now only perform approximately half.

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.

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.

Metallic stent placement in hemodialysis graft patients after insufficient balloon dilation

Objective

We wanted to report our experience of metallic stent placement after insufficient balloon dilation in graft hemodialysis patients.

Materials and Methods

Twenty-three patients (13 loop grafts in the forearm and 10 straight grafts in the upper arm) underwent metallic stent placement due to insufficient flow after urokinase thrombolysis and balloon dilation. The indications for metallic stent deployment included 1) recoil and/or kinked venous stenosis in 21 patients (venous anastomosis: 17 patients, peripheral outflow vein: four patients); and 2) major vascular rupture in two patients. Metallic stents 8-10mm in diameter and 40-80 mm in length were used. Of them, eight stents were deployed across the elbow crease. Access patency was determined by clinical follow-up and the overall rates were calculated by Kaplan-Meier survival analysis.

Results

No procedure-related complications (stent fracture or central migration) were encountered except for a delayed Wallstent shortening/migration at the venous anastomosis, which resulted in early access failure. The overall primary and secondary patency rates (±standard error) of all the vascular accesses in our 23 patients at 3, 6, 12 and 24 months were 69%±9 and 88%±6, 41%±10 and 88%±6, 30%±10 and 77%±10, and 12%±8 and 61%±13, respectively. For the forearm and upper-arm grafts, the primary and secondary patency rates were 51%±16 and 86%±13 vs 45%±15 and 73%±13 at 6 months, and 25%±15 and 71%±17 vs 23%±17 and 73%±13 at 12 months (p = .346 and .224), respectively.

Conclusion

Metallic stent placement is a safe and effective means for treating peripheral venous lesions in dialysis graft patients after insufficient balloon dilation. No statistically difference in the patency rates between the forearm and upper-arm patient groups was seen.

Stent explantation from an arteriovenous fistula for hemodialysis: a case report

Percutaneous transluminal angioplasty is the first treatment of a dysfunctional vascular access for hemodialysis. A case of stenting of a native arteriovenous hemodialysis fistula is reported that was treated with a stent placement at the anastomosis level, with explantation of the stent after complete thrombosis of the fistula 48 hours after the procedure. It is preferable to treat arteriovenous fistulas with simple balloon dilatation, avoiding stenting of the fistula, especially in the anastomosis site.

Percutaneous transluminal angioplasty for Brescia-Cimino hemodialysis fistula dysfunction: technical success rate, patency rate and factors that influence the results

OBJECTIVE

To evaluate the initial clinical success and long-term patency rates of percutaneous transluminal angioplasty (PTA) using a venous approach for dysfunctional Brescia-Cimino fistula and to identify factors that may affect initial success and long-term patency.

MATERIALS AND METHODS

A total of 99 PTA procedures were performed in retrograde fassion for 60 mature Brescia-Cimino shunts with dysfunction caused by anastomotic or peripheral outflow vein stenosis or occlusion. The initial clinical success rates were compared between stenosis and occlusion using Fisher's exact test. The Kaplan-Meier method was used to calculate the primary and secondary cumulative patency rates, and the log-rank test was used for comparison. Relative risks of patency loss according to clinical characteristics were determined with multivariate Cox models.

RESULTS

The initial clinical success rate of all interventions was 92%, and the rates for stenosis and occlusion were 99 and 65%, respectively (P < 0.0001). The primary and secondary cumulative patency rates for fistulas (excluding initial failure) at 12 months were 53 and 84%, respectively. The relative risks were 5.2 (P = 0.004) for longer lesions and 4.5 (P = 0.007) for younger fistulas. The primary cumulative patency rate of four patients with a younger fistula and a longer stenosis at 4 months was 0%.

CONCLUSION

Favorable primary and secondary cumulative patency rates are obtained in most patients. Long lesion length and younger age of fistulas were the two factors that reduced the patency rate after PTA.

Salvage of thrombosed dialysis access grafts with venous anastomosis stents

BACKGROUND

Thrombosis of arteriovenous (AV) grafts caused by stenosis at the venous anastomosis is a well-described problem. Surgical thrombectomy and conventional angioplasty with mechanical thrombectomy have provided good success rates in achieving immediate graft patency but with generally dismal graft survival rates in the range of 11% to 36% at 6 months' follow-up. The role of intravascular stents in patients who have failed angioplasty or surgical revision at the venous anastomosis has not been fully elucidated, particularly in older grafts that have previously undergone multiple procedures.

METHODS

In this series, 34 patients had self-expanding nitinol stents placed at the venous anastomosis following graft thrombectomy and angioplasty procedures. Patients were selected for stent placement if conventional angioplasty alone was unsuccessful due to immediate elastic recoil or residual stenosis. All patients were followed after stent placement and evaluated for duration of graft patency and need for repeated endovascular procedures.

RESULTS

The average graft age at the time of stent placement was 17.9 months. Eight-eight percent of grafts were functioning at 6 months' follow-up, and 63% of the entire group had survived without the need for additional procedures. Among those with need for repeat interventions, 81% had new lesions outside of the stent, and 57% had new lesions within the stent. In 38% of cases, new stenoses were located both outside and within the stent. Among grafts no longer being used, only 19% of the time was it due to disease recurring within the stent.

CONCLUSION

Polytetrafluoroethylene (PTFE) graft longevity is improved when venous anastomosis stenoses are treated with stents in selected cases of older grafts that would have normally undergone abandonment or surgical revision.

Metallic Stent Placement for Treating Peripheral Outflow Lesions in Native Arteriovenous Fistula Hemodialysis Patients After Insufficient Balloon Dilatation

OBJECTIVE

The purpose of this study was to report our experience with metallic stent placement in the peripheral outflow veins in native arteriovenous fistula (A-V fistula) hemodialysis patients after insufficient balloon dilatation.

MATERIALS AND METHODS

During the past 4 years, 12 A-V fistula dialysis patients in our hospital underwent metallic stent placement in the peripheral outflow veins to restore vascular access. The indications for metallic stent placement in our study included (1) recoil stenosis of outflow vein in six patients; (2) outflow venous rupture in two patients and dissection in one patient; and (3) large residual adherent thrombus in outflow aneurysms in three patients with thrombosed (arteriovenous) access. Self-expandable Wallstent or Jostent (Jomed, Abbott Laboratories) of appropriate size (6-10 mm in diameter) was chosen for use in these patients. Kaplan-Meier survival analysis was used to calculate the access patency rates.

RESULTS

Twelve patients received stents. Eleven patients (92%) underwent successful dialysis after the procedure. One patient experienced complications due to incorrect positioning of the stent at the anastomotic site, causing flow compromise. The primary patency (+/- standard error) of the vascular access at 3, 6, 12, and 24 months was 92% +/- 8%, 81% +/- 12%, 31% +/- 17%, and 31% +/- 17%, respectively. The secondary patency of the vascular access at 3 months was 92% +/- 8%, and 82% +/- 12% at 6, 12, and 24 months each.

CONCLUSION

Metallic stent placement is safe and effective in treating peripheral venous lesions in native A-V fistula hemodialysis patients after unsatisfactory balloon dilatation.

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.

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.

The role of interventional radiology in management of patients with end-stage renal disease

The aim of the paper is to review the role of interventional radiology in the management of hemodialysis vascular access and complications in renal transplantation. The evaluation of patients with hemodialysis vascular access is complex. It includes the radiology/ultrasound (US) evaluation of the peripheral veins of the upper extremities with venous mapping and the evaluation of the central vein prior to the access placement and radiological detection and treatment of the stenosis and thrombosis in misfunctional dialysis fistulas. Preoperative screening enables the identification of a suitable vessel to create a hemodynamically-sound dialysis fistula. Clinical and radiological detection of the hemodynamically significant stenosis or occlusion demands fistulography and endovascular treatment. Endovascular prophylactic dilatation of stenosis greater than 50% with associated clinical abnormalities such as flow-rate reduction is warranted to prolong access patency. The technical success rates are over 90% for dilatation. One-year primary patency rate in forearm fistula is 51%, versus graft 40%. Stents are placed only in selected cases; routinely in central vein after dilatation, in ruptured vein and elastic recoil. Thrombosed fistula and grafts can be declotted by purely mechanical methods or in combination with a lytic drug. The success rate of the technique is 89-90%. Primary patency rate is 8-26% per year and secondary 75% per year. The most frequently radiologically evaluated and treated complications in renal transplantation are perirenal and renal fluid collection and abnormalities of the vasculature and collecting system. US is often the method of choice for the diagnostic evaluation and management of the percutaneous therapeutic procedures in early and late transplantation complications. Computed tomography and magnetic resonance are valuable alternatives when US is inconclusive. Renal and perirenal fluid collection are usually treated successfully with percutaneous drainage. Doppler US, magnetic resonance angiography and digital subtraction angiography have a principle role in the evaluation of vascular complications of renal transplantation and management of the endovascular therapy. Stenosis, the most common vascular complication, occurs in 1-12% of transplanted renal arteries and represents a potentially curable cause of hypertension following transplantation and/or renal dysfunction. Treatment with percutaneous transluminal renal angioplasty (PTRA) or PTRA with stent has been technically successful in 82-92% of the cases, and graft salvage rate has ranged from 80 to 100%. Restenosis occurs in up to 20% of cases, but are usually amenable to repeated PTRA. Complications such as arterial and vein thrombosis are uncommon. Intrarenal A/V fistulas and pseudoaneurysms are occasionally seen after biopsy, the treatment requires superselective embolisation. Urologic complications are relatively uncommon, predominantly they consist of the urinary leaks and urethral obstruction. Interventional treatment consists of percutaneous nephrostomy, balloon dilation, insertion of the double J stents, metallic stent placement and external drainage of the extrarenal collections.

Establishing an interventional nephrology suite

Procedures related to dialysis access are best performed in a center or suite designated specifically for that purpose. The facility can either be within a hospital or be a free-standing unit. Feasibility depends largely on the size of the end-stage renal disease population. Alternatives include existing interventional radiology or cardiac catheterization suites. Success of a dialysis access center requires attention to proper physician training, design, staffing, equipment and supplies, and regulations related to procedures, licensing for fluoroscopy, privileges for sedation, and outcome assessment. A successful dialysis access center improves the management of dialysis access and allows the nephrologist to function more efficiently.

Endovascular intervention for the failing vascular access

Endovascular interventions have replaced surgical repair as the primary treatment of the failing or thrombosed vascular access. However, endovascular and surgical techniques are complementary: the limitations of one are the strengths of the other. Endovascular management of access-related problems is a critical component of a successful vascular access monitoring program. The identification and early treatment of developing stenoses, before access thrombosis are essential roles that are ideally suited to percutaneous, image-guided techniques. Despite recent advances in endovascular techniques and devices, angioplasty continues to be the primary method for treatment of access-related stenoses. When appropriate lesions are treated, angioplasty is a fast, easy, and safe procedure that can extend to patency of a hemodialysis graft or fistula.

Percutaneous thrombolysis of thrombosed haemodialysis access grafts: comparison of three mechanical devices

BACKGROUND

Percutaneous thrombolysis has become an accepted treatment of thrombosed haemodialysis grafts. Several devices have been developed for mechanical thrombolysis, which macerate the clot using different mechanisms such as aspiration and fragmentation. The aim of our study was to compare the efficacy of three devices for mechanical thrombolysis in removing the thrombus from thrombosed haemodialysis access grafts and to determine the initial technical and clinical success, complication rates of each device, and graft patency after the procedure.

METHODS

Thrombolysis (i.e. clot removal followed by percutaneous transluminal angioplasty (PTA)) was performed in 68 thrombosed haemodialysis grafts using the Cragg brush catheter combined with urokinase in 13, the Hydrolyser in 18 and the Arrow-Trerotola Percutaneous Thrombolytic Device (PTD) in 37. Clot removal scores (CRS, the ability to thoroughly remove clot from the access), initial technical success, clinical success, patency at 30, 60, and 90 days, and complication rates were evaluated.

RESULTS

CRS for the Cragg brush, Hydrolyser and PTD were good in 92, 44, and 95% of cases, respectively. Initial technical (85, 83, and 95%) and clinical success (62, 67, and 86%), mean patency rates at 30 (73, 60, and 55%), 60 (61, 53, and 49%), and 90 (49, 40, and 43%) days, stenosis after PTA (33, 46, and 21%) and complication rates (8, 6, and 0%) were not different for the three devices. Success rates and graft patency depended on the effect of PTA, irrespective of the device used.

CONCLUSIONS

The rotational devices removed clots more effectively than the Hydrolyser, with the PTD having the advantage of not requiring urokinase. However, the result of PTA in the treatment of underlying stenoses was the only predictive value for graft patency.

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 the mechanical thrombectomy efficacy of the Amplatz thrombectomy device and the Cragg thrombolytic brush in vitro

RATIONALE AND OBJECTIVES

To determine the efficacy of thrombectomy (without thrombolytic agents) for the Amplatz thrombectomy device (ATD) and the Cragg thrombolytic brush catheter (CBC) in vitro.

METHODS

Thrombectomy was performed with the ATD or CBC (6F) in a flow model. Embolus sizes, weight, remaining thrombus, and activation time were evaluated.

RESULTS

No significant difference in the activation time was found. The CBC produced significantly less embolism (3.3% vs. 0.03% in the 5-mm and 89% vs. 0.5% in the 7-mm model), but also much more thrombus remained in the system than with the ATD (1% vs. 41% in the 5-mm and 0.1% vs. 62% in the 7-mm model).

CONCLUSIONS

The ATD can remove almost all thrombus (99%), whereas the CBC removes only up to 60%, producing fewer emboli than the ATD. This might be due to the lower rotational speed of the CBC compared with the ATD, which is 20 times greater. The soft nylon brush offers less resistance and shear force toward the thrombus than the stainless-steel impeller of the ATD. Because of the large amount of remaining thrombus, the CBC should not be used without lytic agents.

Brachial arterial access: endovascular treatment of failing Brescia-Cimino hemodialysis fistulas--initial success and long-term results

PURPOSE

To evaluate safety and efficacy of endovascular interventions in failing antebrachial Brescia-Cimino hemodialysis fistulas in consecutive patients.

MATERIALS AND METHODS

Altogether, 103 interventions were performed in 53 Brescia-Cimino shunts in 51 patients by means of antegrade brachial arterial access. Twelve interventions were initiated with pharmacomechanical thrombolysis and/or thromboaspiration. All interventions included balloon angioplasty that was completed with stent placement in eight cases and with endovascular brachytherapy with an iridium 192 source in five cases.

RESULTS

The technical success rate of the primary interventions was 92% (49 of 53) and that for all interventions was 95% (98 of 103). The rate of major complications was 4% (four of 103). Clinical success was achieved in 92% (95 of 103) of the interventions. By including the initial failures, 58% +/- 7 (standard error of the estimate), 44% +/- 8, 40% +/- 8, and 32% +/- 10 primary and 90% +/- 5, 85% +/- 5, 79% +/- 7, and 79% +/- 7 secondary clinical patency rates were registered at 6 months and 1, 2, and 3 years, respectively, by means of Kaplan-Meier analysis. The location of the main treated lesion at the arteriovenous anastomosis (P =.03) was a predictor of poorer long-term patency.

CONCLUSION

Endovascular interventions with antegrade brachial arterial access are highly effective in restoring function in failing Brescia-Cimino fistulas.

Treatment of stenosis and thrombosis in haemodialysis fistulas and grafts by interventional radiology

BACKGROUND

There are no large series reporting the long-term results after radiological treatment of both stenosis and thrombosis in native fistulas (AVFs) and prosthetic grafts.

METHODS

Between 1987 and 1999, 726 dilations, 135 stent placements and 257 declotting procedures were performed in 209 consecutive forearm AVFs, 74 upper arm AVFs and 156 prosthetic grafts. The stents used were the Wallstent*, the Craggstent*, and the Passager*. Declotting was performed by manual catheter-directed thromboaspiration, with or without previous urokinase infusion.

RESULTS

The initial success rates ranged from 78 to 98%. The rate of significant complications was 2%. Primary patency rates at 1 year were twice as good for forearm AVFs (50%) than for grafts (25%) (P<0.05), and were 34% for upper arm AVFs. Secondary patency rates were similar in the 3 groups at 1 year (80-86%) and at 2 years (68-80%). Reintervention was necessary every 18 months in forearm AVFs compared to every 9 months in grafts (P<0.05). Thrombosed grafts fared worse than failing grafts. Accesses of less than 1 year's duration needed more reinterventions than older accesses (every 16 months versus 30 in forearm AVFs, every 7 months versus 13 in grafts, P<0.05).

CONCLUSIONS

The percutaneous treatment of stenosis and thrombosis in haemodialysis access achieves patency rates similar to those reported in the surgical literature and confirms that grafts must be avoided as much as possible given their poorer outcome, especially after the first thrombosis. Poorer outcome is also demonstrated in accesses of less than 1 year's duration.

Improvement in hemodialysis vascular access outcomes in a dedicated access center

There are more than 300,000 end-stage renal disease (ESRD) patients in the United States, with those on hemodialysis requiring vascular access for dialysis treatment. According to the 1999 annual report of the U.S. Renal Data System (USRDS), the leading cause of morbidity in this patient population is related to vascular access placement and the resultant complications. Vascular access procedures account for more than 10% of the annual ESRD budget and are conservatively estimated at $1 billion annually. The impact of dysfunctional vascular access on physician time, health care resources, and patient quality of life is profound. In 1997 I opened a freestanding, dedicated access center for the diagnosis and treatment of access-related disorders. This article summarizes the experience of this center. In our free-standing dialysis access center, a large referral base has been established consisting of 30 dialysis centers with approximately 2000 patients. During the 27 months from October 1997 to December 1999, 1087 patients were treated. These patients received 2862 access procedures (2.6 procedures/patient). Annualized, this gives a dysfunction rate of 1.15 episodes/patient/year at risk. Endovascular declotting procedures were performed 1282 times (45%) with a success rate (defined as one uneventful hemodialysis following the procedure) of 93% (1187/1282). Prospective angiography followed by percutaneous transluminal angioplasty was performed 703 times (24%). This procedure was successful 695 times for a success rate of 99%. There were 644 (23%) catheter procedures performed consisting of catheter placements, catheter exchanges through new or old tracts, and catheter removals. The success rate for catheter procedures was 99.1%. Complication rates were extremely low, both for major and minor complications, exceeding all published standards. Hemodialysis vascular access can be optimized in a freestanding, focused, outcomes-driven outpatient access center. Outcomes can meet or exceed the National Kidney Foundation Dialysis Outcomes Quality Initiative (NKF-DOQI) guidelines for vascular access while at the same time providing the patient with an outpatient procedure and the referring dialysis unit and nephrologist with an efficient, effective mode of patient care.

Mechanical thrombolysis of thrombosed hemodialysis native fistulas with use of the Arrow-Trerotola percutaneous thrombolytic device: our preliminary experience

PURPOSE

To evaluate the feasibility of use of the Arrow-Trerotola percutaneous thrombolytic device (PTD) in the treatment of thrombosed hemodialysis native fistula occlusions.

MATERIALS AND METHODS

Ten patients with native fistula occlusion underwent mechanical thrombolysis with use of the PTD. The standard PTD was used in seven patients and the over-the-wire device was used in three patients. Major outcomes of our study included procedure time, clinical success, complication rate, and 3- and 6-month patency rates.

RESULTS

The technical success rate was 100% and the clinical success rate was 90% (9 of 10). In all 10 cases, the procedure was associated with angioplasty. There were no major complications. The mean time of successful procedures was 126.1 minutes. The 3- and 6-month primary patency rates were 70% and 60%, respectively; the assisted primary patency rate at 6 months was 80%.

CONCLUSION

The PTD is an effective mechanical device for percutaneous treatment of thrombosed hemodialysis access. Our clinically successful initial experience with the PTD shows that the technique is rapid and safe for treatment of native fistula occlusions.