Improved treatment of thrombosed hemodialysis access sites with thrombolysis and angioplasty

Outcomes of endovascular treatment for stenosis occurring after cephalic vein transposition and graft interposition

OBJECTIVE

To evaluate the outcome of endovascular treatment after surgical treatment for cephalic arch stenosis in brachiocephalic fistula and to analyze the factors influencing patency.

METHODS

We conducted a retrospective review of patients undergoing cephalic transposition (CVT) or graft interposition (GIP) for cephalic arch stenosis (CAS) from January 1, 2017, to December 31, 2019. A total of 73 patients with restenosis were included in this study. Patients were classified into cephalic transposition (BCF-CVT) (n=49) and graft interposition (BCF-GIP) (n=24) groups. We calculated the postintervention primary and secondary patency of endovascular treatment by using the Kaplan-Meier analysis and analyzed variables associated with loss of postintervention patency.

RESULTS

Six-month and 12 month postintervention primary patency rates of endovascular treatment for restenosis were 56.7% and 15.6% and secondary patency rates were 89.7% and 72.1%, respectively. In BCF-CVT group, six month, and 12 month postintervention primary patency was 56.8% and 17.6% and secondary patency was 93.3% and 79.4%, respectively. In BCF-GIP group, six-month, and 12 month postintervention primary patency was 56.5% and 8.7% and secondary patency was 85.7% and 56.3%, respectively. There was no significant difference in postintervention primary patency between the two groups (p=0.79). However, BCF-CVT group demonstrated higher postintervention secondary patency (p=0.034). BCF-GIP group had a higher number of stenosis sites (p<0.01). There was no significant predictor of reduced postintervention primary patency. The only adverse variable of postintervention secondary patency was BCF-GIP (Hazard ratio 3.14; 95% CI 1.06 to 9.34, p <0.05).

CONCLUSION

Endovascular treatment is still the acceptable option for stenosis occurring after surgical treatment for CAS. CVT provides higher postintervention secondary patency than GIP.

Safety and Efficacy of the Percutaneous Manual Aspiration Thrombectomy Technique to Treat Thrombotic Occlusion of Native Arteriovenous Fistulas for Hemodialysis

목적

대상과 방법

결과

결론

Temporal distribution and biological determinants of thrombotic events after interventions for dialysis vascular access

Endovascular therapy is the principal therapy for haemodialysis vascular access dysfunction. Nonetheless, the incidence and determinants of post-intervention thrombotic events are unclear. This prospective cohort study evaluated the incidence and timing of thrombotic events after endovascular therapy and analysed the clinical, angiographic, and biological determinants of thrombosis. Of the 236 patients enrolled, 91 experienced post-intervention thrombotic events within 1 year. The 1-year thrombosis-free patency was 28% for thrombosed accesses, 53% for non-thrombosed grafts, and 78% for non-thrombosed fistulas. Forty-one of the 91 thrombotic events (45%) occurred within 3 months post-intervention. In the univariate analysis, early thrombosis was associated with longer haemodialysis duration (hazard ratio [HR], 1.01; 95% confidence interval [CI], 1.01–1.02), graft access (HR, 7.69; 95% CI, 3.33–20.0), multiple stenoses (HR, 2.69; 95% CI, 1.36–5.37), and high indoxyl sulphate (IS) levels (HR, 1.55; 95% CI, 1.32–1.82). Late thrombosis was associated with diabetes (HR, 1.89; 95% CI, 1.01–3.57), cardiovascular disease (HR, 2.38; 95% CI, 1.27–4.54), and endothelial progenitor cell counts (HR, 0.97; 95% CI, 0.93–0.99). After multivariate adjustment, high IS was the major predisposing factor for early post-intervention thrombosis (HR, 1.41; 95% CI, 1.18–1.69). Our findings suggest that measures to decrease IS could target the most critical period of thrombosis.

Surgery versus Interventional Radiology in the Management of Thrombosed Vascular Access for Hemodialysis

Thrombosis is the most frequent complication occurring in vascular access (VA). The two widely used treatment strategies for thrombosed VA are surgical and endovascular. Which is the best and whether different approaches should be used on proximal versus distal VA, is still debated. This is a retrospective study. Over a three years period, we studied among a population of 475 dialysis patients, 54 VA thromboses in 46 patients. Surgical procedure was successful in 14/17 (82%) distal artero-venous fistulas (AVF) while, in 9 proximal AVF, it led to initial success in 6 patients (66%), with a six months primary patency respectively of 93% and 84%. Radiological procedure resolved 6/10 distal AVF (initial success 60%) with primary patency of 66%, and was successful in 16/18 proximal AVF (initial success 89%) with primary patency of 81%. Taking our data all together, no differences are found between two thrombolitic (surgical and endovascular) procedures. But results were different in thrombosed proximal VA (where endovascular treatment should be preferred) versus distal ones (where surgery seems better).

Management of venous hypertension following arteriovenous fistula creation for hemodialysis access

INTRODUCTION

Venous hypertension (VH) is a distressing complication following the creation of arteriovenous fistula (AVF). The aim of management is to relieve edema with preservation of AVF. Extensive edema increases surgical morbidity with the loss of hemodialysis access. We present our experience in management of VH.

METHODS

A retrospective study was conducted on 37 patients with VH managed between July 2005 to May 2014. Patient demographics, evaluation, and procedures performed were noted. A successful outcome of management with surgical ligation (SL), angioembolization (AE), balloon dilatation (BD) or endovascular stent (EVS) was defined by immediate disappearance of thrill and murmur with resolution of edema in the next 48-72 h, no demonstrable flow during check angiogram and resolution of edema with preservation of AVF respectively.

RESULTS

All 8 distal AVF had peripheral venous stenosis and were managed with SL in 7 and BD in one patient. In 29 proximal AVF, central and peripheral venous stenosis was present in 16 and 13 patients respectively. SL, AE, BD, and BD with EVS were done in 18, 5, 4, and 3 patients, respectively. All patients had a successful outcome. SL was associated with wound related complications in 11 (29.73 %) patients. A total of 7 AVF were salvaged. One had restenosis after BD and was managed with AE. BD, EVS, and AE had no associated morbidity.

CONCLUSIONS

Management of central and peripheral venous stenosis with VH should be individualized and in selected cases it seems preferable to secure a new access in another limb and close the native AVF in edematous limb for better overall outcome.

Influence of drugs on arteriovenous vascular access dysfunction

Vascular access dysfunction, due to venous stenosis at the vein-artery anastomosis in arteriovenous fistulas and vein-graft anastomosis in synthetic arteriovenous grafts, is a major cause of morbidity and mortality in dialysis patients. The two overarching approaches to prevent and treat vascular access dysfunction are from systemic or local (including endovascular and perivascular) routes. However, there are currently very few effective therapies to treat vascular access dysfunction. This article will review major studies evaluating systemic, endovascular, and perivascular therapies for vascular access dysfunction. Ongoing research to evaluate novel innovations to prevent and/or manage vascular access dysfunction appears promising.

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.

Assessing the approach to a thrombosed AV graft

The patency of the vascular access (VA) is a fight for the attending nephrologist. A retrospective observational study was conducted to compare the success rate of surgical versus endovascular technique percutaneous transluminal angioplasty (PTA) for graft thrombosis treatment. Of 3008 patients, 22.1% patients were dialyzed through grafts. Forty-five percent of all prevalent patients referred due to VA malfunction had a graft. For 18 months, 336 thrombosed grafts were submitted to surgery in 228 cases and to PTA in 126. PTA for thrombolysis included the Pharmaco-Mechanical Technique and the Arrow-Trerotola Device. Procedures were performed as outpatient, with an average delay of 1 day. Immediate success was 100% for surgery and 87.3% for PTA. The unassisted patency for thrombosed grafts for surgery/PTA was 265.12 ± 15.30/230.59 ± 19.83 days respectively, favoring surgery. The primary patency for thrombosed grafts treated by surgery/PTA at 30, 90, and 180 days was, respectively, 74.1%/81%, 63.2%/67.5%, and 53.9%/55.6% all in favor of PTA. AV grafts have a much higher rate of thrombosis than fistulas. Graft thrombosis can be dealt either by surgery or PTA, with identical success.

Use of Hybrid Vascular Grafts in Failing Access for Hemodialysis: Report of Two Cases

Purpose

Vascular access morbidity represents one of the most common indications for readmission in patients with end-stage renal disease (ESRD). We report the use of hybrid grafts in two patients for revision of failed vascular access for hemodialysis (HD).

Case Presentations

The first patient was a 45-year-old woman with ESRD who presented with an arteriovenous graft (AVG) that had required multiple interventions for maintenance in whom much of the graft was lined with covered stents. The patient presented with erosion of a stent in the AVG through the skin to the emergency department. The second patient was a 41-year-old man with ESRD who also had an AVG that had required multiple interventions for maintenance. He presented to clinic with chronic bleeding from the AVG after HD sessions. Both patients were taken to the operating room for salvage of part of the AVG through the use of hybrid vascular access grafts. The patients have passed six and three months from the procedure, respectively, without needing additional interventions.

Conclusions

This technique demonstrates successful use of hybrid vascular access grafts, specifically inside existing grafts in locations that contain stents utilizing the existing venous resources in that arm to carry out the surgical repair, thereby preserving venous capital.

Treating thrombotic prosthetic arteriovenous access with cross-balloon occlusive thrombolysis and angioplasty

OBJECTIVE

Clot embolism remains a concern due to flushing of clot and thrombolytic agent centrally in the process of percutaneous pharmacomechanical thrombolysis (PMT) for a thrombosed prosthetic arteriovenous access (PAVA), which might be reduced by a modified technique.

METHODS

We retrospectively review this modified technique that uses two balloon-catheters in crisscross fashion and occludes both ends of PAVA during thrombolysis. Underlying stenotic lesions were dilated simultaneously with balloon angioplasty when needed.

RESULTS

Among the 23 patients treated, 21 (91.3%), 10 (43.5%), and seven (30.4%) presented significant stenosis at the outflow, intragraft, and inflow segments of PAVA, respectively. The median duration of follow-up was 310.0 (range, 288.0-327.0) days. Anatomic success was achieved in 12 out of 23 (52.2%). Clinical success for successful dialysis was achieved in all patients. The median primary patency and secondary patency were 126.0 days (range, 7.0-316.0) days and 308.0 days (range, 84.0-327.0), respectively.

CONCLUSION

We believe this method is safe and effective in dissolving PAVA thrombus as well as treating culprit stenosis. It may reduce concerns of flushing of clot and thrombolytic agent into the central circulation in the process of PMT.

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

Objective

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

Materials and Methods

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

Results

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

Conclusion

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

Surgical aspects and biological considerations of arteriovenous fistula placement

Since the Fistula First Initiative was formulated in 2003, providers and payers have increasingly emphasized the need to create more arteriovenous fistulae. To maximize the chances of successful fistula maturation, a thorough understanding of the biology and surgical aspects of fistula placement are essential. A functional endothelium in the target vessels is the prerequisite for the adaptive remodeling of the vessel wall, which has to take place after fistula formation. Mechanoreceptors of the endothelium sense the increase in shear stress and, through a variety of activated signaling cascades, induce the necessary changes and vasodilation of the respective vessels. The successful fistula placement starts with a thorough preoperative evaluation, which focuses on protecting the target vessels and avoiding intravenous catheters and devices. Intraoperatively, the risk of endothelial dysfunction and hyperplasia is further minimized through an atraumatic dissection with minimal manipulation of the vein and artery. The surgical technique should also focus on decreasing the vessel compliance mismatch and avoiding an inflammatory response secondary to hematoma formation. Postoperatively, the fistula must be diligently monitored for the complications of thrombosis, postoperative steal syndrome, neuropathy, aneurysm formation, infection, and high-output cardiac failure. Early recognition of a problem is the key to saving an otherwise doomed fistula. An armamentarium of percutaneous techniques is available to the access surgeon to treat the most common causes of failed access formation. However, in some cases a surgical revision of the access site through patch angioplasty, a jump graft, and graft interposition is necessary to create a fistula which can be successfully used for hemodialysis.

Hemodialysis vascular access monitoring: current concepts

Most arteriovenous grafts fail due to irreversible thrombosis, and most clotted grafts have an underlying stenotic lesion. These observations raise the plausible hypothesis that early detection of graft stenosis with preemptive angioplasty will reduce the likelihood of graft thrombosis. A number of noninvasive methods can be used to detect hemodynamically significant graft stenosis with a high positive predictive value. These tests include clinical monitoring, as well as surveillance by static dialysis venous pressures, flow monitoring, or duplex ultrasound. However, these surveillance tests have a much lower positive predictive value for graft thrombosis in the absence of preemptive angioplasty. In other words, none of the currently available surveillance tests can reliably distinguish between stenosed grafts destined to clot, and those that will remain patent without intervention. As a consequence, any program of graft surveillance necessarily results in a substantial proportion of unnecessary angioplasties. Moreover, a substantial proportion of grafts thrombose despite a normal antecedent surveillance test. Numerous observational studies have found an impressive reduction of graft thrombosis after implementation of a stenosis surveillance program. In contrast, 5 of 6 randomized clinical trials failed to show a reduction of graft thrombosis in patients undergoing graft surveillance, as compared with those receiving only clinical monitoring. The lack of benefit of surveillance is largely attributable to the rapid recurrence of stenosis after angioplasty. Thus, routine surveillance for graft stenosis, with preemptive angioplasty, cannot be recommended for reduction of graft thrombosis. Future research should be directed at pharmacologic interventions to prevent graft stenosis.

Is surgical salvage of arteriovenous grafts feasible after unsuccessful percutaneous mechanical thrombectomy?

Treatment of thrombosed dialysis ateriovenous (AV) grafts in the radiology interventional suite requires percutaneous mechanical thrombectomy, along with angioplasty of the underlying stenotic lesion. We analyzed the anatomic reasons for unsuccessful percutaneous thrombectomy of AV grafts, and assessed the feasibility of surgical salvage. The radiologic reports of all thrombosed AV grafts undergoing unsuccessful percutaneous mechanical thrombectomy during a 5-year period were analyzed for the specific problem precluding restoration of graft patency. We also compared the features of patients with unsuccessful graft thrombectomy to those with successful thrombectomy. Of 77 AV grafts undergoing unsuccessful percutaneous thrombectomy, only six (or 8%) could be revised surgically. Inability to salvage the graft surgically was because of: severe draining vein occlusion or stenosis (30 patients); severe central vein lesion (12); multiple intragraft stenoses (11); large pseudo-aneurysms (six); venous anastomotic occlusion (six); and arterial anastomotic occlusion (four). When compared with 211 patients with successful graft thrombectomy, those with unsuccessful thrombectomy were more likely to have a forearm graft (53% vs. 27%, p < 0.001), and more likely to have a lesion in the draining vein (42% vs. 10%, p < 0.001), the central vein (17% vs. 3%, p < 0.001), or within the graft itself (23% vs. 1%, p < 0.001). An unsuccessful percutaneous graft thrombectomy is more likely in forearm than in upper arm grafts, and more likely if there is a lesion in the draining vein, central vein, or within the graft itself. Surgical salvage of a thrombosed AV graft after an unsuccessful percutaneous intervention is rarely feasible. Most patients have a severe anatomic lesion that cannot be repaired, and require creation of a new vascular access.

Current management of vascular access

Optimizing vascular access outcomes remains an ongoing challenge for clinical nephrologists. All other things being equal, fistulas are preferred over grafts, and grafts are preferred over catheters. Mature fistulas have better longevity and require fewer interventions, as compared with mature grafts. The major hurdle to increasing fistula use is the high rate of failure to mature of newly created fistulas. There is a desperate need for enhanced understanding of the mechanisms of failure to mature and the optimal type and timing of interventions to promote maturity. Grafts are prone to frequent stenosis and thrombosis. Surveillance for graft stenosis with preemptive angioplasty may reduce graft thrombosis, but recent randomized clinical trials have questioned the efficacy of this approach. Graft stenosis results from aggressive neointimal hyperplasia, and pharmacologic approaches to slowing this process are being investigated in clinical trials. Catheters are prone to frequent thrombosis and infection. The optimal management of catheter-related bacteremia is a subject of ongoing debate. Prophylaxis of catheter-related bacteremia continues to generate important clinical research. Close collaboration among nephrologists, surgeons, radiologists, and the dialysis staff is required to optimize vascular access outcomes and can be expedited by having a dedicated access coordinator to streamline the process. The goal of this review is to provide an update on the current status of vascular access management.

Economic implications of screening strategies in arteriovenous fistulae

Practice guidelines recommend performing angiography in arteriovenous fistulae (AVF) when access blood flow (Qa) is < 500 ml/min, but a Qa threshold of <750 ml/min is more sensitive for stenosis. No economic evaluation has evaluated the optimal Qa threshold for angiography in AVF, or Determined whether screening AVF is more economically efficient than intervening only when AVF is thrombosed. We compared two screening strategies using Qa thresholds of <750 and <500 ml/min, respectively, with no access screening. Expected per-patient access-related costs (in 2002 Canadian dollars) were $3910, $5130, and $5250 in the no screening, QA500, and QA750 arms, respectively over 5 years. Notably, screening strategies did not reduce expected access-related costs under any clinically plausible scenario. The cost to prevent one episode of AVF failure appeared to be approximately $8000-$10,000 over 5 years for both screening strategies, compared with no screening. Although the incremental cost effectiveness of screening (compared to no screening) was similar in the base case for the QA500 and QA750 strategies, the relative economic attractiveness of the QA750 strategy was adversely affected under several plausible scenarios. Also, the QA750 strategy would require many additional angiograms to prevent an additional episode of AVF failure compared with the QA500 strategy. Screening of AVF resulted in a modest increase in net costs and seems to require a net expenditure of approximately $9000 to prevent one episode of AVF failure. If screening is adopted, our findings suggest that angiography should be performed when Qa is <500 rather than <750 ml/min, especially when access to angiography is limited.

Outcomes of thrombosed arteriovenous grafts: Comparison of stents vs angioplasty

The usual radiologic approach to thrombosed grafts is a combination of thrombectomy and angioplasty of the underlying lesion. However, the primary (unassisted) graft patency after thrombectomy is quite poor. We evaluated whether graft patency following thrombectomy is improved by placement of a stent in the stenotic lesion. Using a prospective, computerized vascular access database, we identified 14 patients with thrombosed arteriovenous (A-V) grafts treated with a stent at the venous anastomosis (stent group). The outcomes of these grafts was compared to those observed in 34 sex, age-, and date-matched control patients whose thrombosed A-V grafts were angioplastied (control group). Both groups were comparable in age, sex, race, diabetic status, graft age, and number of previous graft interventions. The immediate technical success, as indicated by the post-procedure graft to systemic pressure ratio, was similar in the stent and control groups (0.33+/-0.16 vs 0.41+/-0.17, P=0.14). The primary graft patency (time from thrombectomy to next intervention) was significantly longer for the stent group (median survival, 85 vs 27 days, P=0.02). Assisted or secondary patency (time from thrombectomy to permanent graft failure) was also longer for the stent group (median survival, 1215 vs 46 days, P=0.049). In conclusion, treatment of thrombosed grafts with a stenosis at the venous anastomosis with a stent results in longer primary and secondary graft survival, as compared to treatment with angioplasty. Stent placement may be a useful treatment modality in a subset of patients with thrombosed A-V grafts and stenosis at the venous anastomosis.

Combination of duplex ultrasound-guided manual declotting and percutaneous transluminal angioplasty in thrombosed native dialysis fistulas

BACKGROUND

To investigate the safety, feasibility, efficacy, and long-term patency rate of manual declotting under duplex ultrasound (US) guidance followed by percutaneous transluminal angioplasty (PTA) in thrombosed native arteriovenous fistulas (AVFs).

METHODS

Of 87 consecutive thrombosed AVFs evaluated by duplex US, 22 patients with 25 recently thrombotic events in 22 AVFs were suitable for manual declotting. PTA was performed following successful declotting, and long-term patency was assessed.

RESULTS

The procedure success rate of manual declotting was 80% (20 of 25), and a residual stenosis of 74+/-9% was identified by duplex US after declotting. PTA reduced the diameter stenosis to 25+/-6% and increased the lumen diameter from 1.33 +/-0.85 mm to 4.62+/-0.98 mm. Neither embolic nor bleeding complications were noted during the procedure. The average procedure time and the fluoroscopy time were 28.4+/-9.9 and 7.2+/-4.1 minutes, respectively. Primary patency rates at 1, 2, and 3 years were 47%, 35%, and 28%; assisted primary patency rates at 1, 2, and 3 years were 71%, 63%, and 63%; and secondary patency rates at 1, 2, and 3 years were 76%, 71%, and 63%, respectively, during a maximum follow-up period of 42 months.

CONCLUSION

The combination of duplex US-guided manual declotting and angioplasty of underlying stenosis is a safe and feasible method to treat recently thrombosed native AVFs in selected patients. It simplifies the interventional procedure, reduces cost and radiation exposure time, and extends life span of dialysis fistula with acceptable long-term patency rate.

Endovascular management of immediate procedure-related complications of failed hemodialysis access recanalization

Endovascular procedures are becoming the standard type of care for the management of hemodialysis vascular access dysfunction. As with any type of medical procedure, these techniques can result in procedure-related complications, although the expected number of complications is low. The clinical extent of these complications varies from case to case. Management of these cases depends on the clinical presentation. Major complications such as vein rupture, arterial embolism, remote site bleeding or hematoma, symptomatic pulmonary embolism and puncture site complications necessitating treatment require major therapy. Minor complications such as non-flow compromising small puncture site hematoma or pseudoaneurysms require little or no therapy. It is essential that the interventionist be prepared to manage these complications appropriately when they arise.

Comparison of SMART Stent Placement for Arteriovenous Graft Salvage versus Successful Graft PTA

PURPOSE

To compare the SMART (shape memory alloy recoverable technology) stent with percutaneous transluminal angioplasty (PTA) alone in hemodialysis access venous stenoses.

MATERIALS AND METHODS

A prospective, nonrandomized study was undertaken in 60 patients with dysfunctional polytetrafluoroethylene dialysis grafts. Indications for stent placement were acute PTA failure, rapid restenosis, and vessel perforation. The primary endpoint was improved graft patency in patients treated with stents compared with that in patients whose disease responded to PTA alone. The secondary endpoints were lower postprocedural midgraft pressures and similar complication rates compared with PTA alone.

RESULTS

The key venous stenosis was at the graft-to-vein anastomosis in all but two patients. Thirty-five patients showed a response to PTA alone. Sixteen patients received stents for stenoses greater than 30% after angioplasty, six for rapidly recurrent stenosis, and three for venous rupture. Nine patients received stents across the level of the elbow joint. Stenosis after intervention was significantly less frequent in the stent group (7% vs 16%; P = .001), but the midgraft systolic pressure ratios did not significantly differ. The clinical success rates were 100% after stent implantation and 97% after PTA alone. Except for venous rupture, there were no procedure-related complications, and, excluding early graft thrombosis, there were no complications at 30 days. A single stent fracture was found on follow-up. The mean primary graft patency times were 5.6 months after PTA and 8.2 months after stent treatment (P = .050). When stents were placed across the level of the elbow joint, the mean primary graft patency time was 8.9 months.

CONCLUSION

Implantation of the SMART stent is safe and effective for the treatment of residual or rapidly recurrent dialysis access venous stenoses and is associated with better patency than PTA alone.

SMART Stent for Salvage of Hemodialysis Access Grafts

PURPOSE

To evaluate the SMART stent for treating angioplasty-resistant hemodialysis access venous stenoses.

MATERIALS AND METHODS

A retrospective study of 64 patients with polytetrafluoroethylene grafts who were treated with the SMART stent at 69 locations in the venous outflow tract was undertaken. Stents were used for elastic recoil after percutaneous transluminal angioplasty, venous rupture, or recurrent stenosis less than 3 months after angioplasty. When angiographic follow-up was available, the degree of in-stent restenosis was measured. Primary patency was determined, and, when applicable, compared with that of previous angioplasty treatments of the same lesion.

RESULTS

The SMART stent was placed in 15 central veins and 54 peripheral veins, with a 98% technical success rate and a 97% clinical success rate. The mean primary access patency times were 14.9 months and 8.9 months in patients who received central and peripheral stents, respectively. In 19 patients whose central or peripheral venous stenoses were previously treated with angioplasty, the mean primary access patency was increased from 2.5 months to 10.6 months after placement of the SMART stent (P = .0003). Angiography in 29 patients after an average of 348 days showed 55% mean in-stent stenosis. The only stent-related complication occurred in a patient who had venous dissection associated with the edge of a SMART stent placed at the elbow.

CONCLUSION

The SMART stent is safe and effective for treating dialysis access venous stenoses that are resistant to standard angioplasty.

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

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

Percutaneous treatment of complications occurring during hemodialysis graft recanalization

INTRODUCTION/OBJECTIVE

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

METHODS AND MATERIALS

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

RESULTS

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

DISCUSSIONS AND CONCLUSION

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

A Preliminary Investigation of Balloon Angioplasty versus Surgical Treatment of Thrombosed Dialysis Access Grafts

It has been estimated that 180,000 patients in the United States have end-stage renal disease requiring hemodialysis, and this number is currently increasing at a rate of 10 per cent per year. With the growing number of patients requiring hemodialysis the insertion and maintenance of dialysis access has become a common task for vascular surgeons. In fact dialysis access is now the most common vascular operation and may account for as much as 40 to 50 per cent of the practice of a busy vascular surgeon. The two major techniques for repairing thrombosed dialysis access grafts are open surgical revision and balloon angioplasty. Surgical revisions of access sites include patch angioplasty and interposition jump grafts. Balloon angioplasty involves declotting the graft mechanically or chemically followed by dilation of the stenotic segment by an angioplasty balloon under fluoroscopy. Few studies have compared the two methods of repair, and the studies that have been done reveal conflicting results. A retrospective chart review of patients treated at the New Hanover Regional Medical Center for repair of thrombosed dialysis access grafts was conducted. The final sample available for analysis consisted of 16 patients with balloon angioplasty and 44 patients with surgical revision. These two groups were compared in terms of demographics, past medical history, surgery time, complications, length of stay, length of graft patency, and typical costs. Overall balloon angioplasty as compared with surgical revision was associated with longer patency (5.5 vs 3.2 months), shorter surgical time (43.9 vs 64.5 minutes), shorter length of hospital stay (less than one day vs one day or more), and fewer complications (12% vs 30% of the patients). We concluded from this analysis that endovascular treatment of thrombosed dialysis grafts is an acceptable alternative to surgical revision and should be the first option after primary failure of the grafts caused by stenotic lesions.

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.

Does surgical intervention significantly prolong the patency of failed angioaccess grafts previously treated with percutaneous techniques?

In the last decade, percutaneous techniques have been increasingly used to treat angioaccess graft thrombosis. Often when catheter-based treatment fails, surgeons are called upon to treat these occluded bridge fistulas. It has been our impression that operative intervention has not significantly increased the longevity of angioaccess grafts that have failed percutaneous intervention. During a 2-year period, 101 operative procedures were performed on failed bridge fistulas. All had previously been treated with percutaneous thrombolysis and dilatation. The number of previous interventions ranged from one to five. Primary patency rates of the angioaccess grafts following surgical revision were 43%, 24%, and 12% at 30, 60, and 90 days, respectively. We conclude that surgical intervention does not significantly prolong the patency of angioaccess grafts that have previously failed percutaneous interventions and that its routine use cannot be recommended.

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Contemporary treatment of thrombosed hemodialysis grafts

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

Predictors of arteriovenous graft patency after radiologic intervention in hemodialysis patients

Arteriovenous grafts in hemodialysis patients are prone to recurrent stenosis and thrombosis, requiring frequent radiologic and surgical interventions to optimize their long-term patency. Little is known about the factors that determine graft outcome after a radiologic intervention. The present study examined the clinical and radiologic predictors of intervention-free graft survival after elective angioplasty or thrombectomy. A prospective computerized database was used to determine the outcomes subsequent to all graft angioplasties (n = 330) and thrombectomies (n = 326) performed at the University of Alabama at Birmingham between April 1, 1996, and June 30, 1999. Primary graft survival rates after angioplasty and thrombectomy were 86% versus 43% at 1 month, 71% versus 30% at 3 months, 51% versus 19% at 6 months, and 28% versus 8% at 12 months, respectively. The median intervention-free graft survival time was substantially longer after angioplasty than thrombectomy (6.7 versus 0.6 months; P < 0.001). The superior outcome of angioplasty over thrombectomy was observed even for the subset of procedures with no residual stenosis (median survival, 6.9 versus 2.5 months; P < 0.001). The median graft survival was inversely related to the magnitude of residual stenosis for both elective angioplasty and thrombectomy. Median intervention-free graft survival after angioplasty was inversely related to the postangioplasty intragraft to systemic systolic pressure ratio (7.6, 6.9, and 5.6 months for ratios <0.4, 0.4 to 0.6, and >0.6, respectively; P < 0.001). Intervention-free graft survival after angioplasty or thrombectomy was not affected by graft location (forearm versus upper arm), number of stenotic sites, or presence of diabetes. In conclusion, graft survival is substantially longer after elective angioplasty than thrombectomy, even when the radiologic appearance after the procedure suggests complete resolution of the stenotic lesion. Moreover, the risk for requiring a subsequent graft intervention can be predicted from two simple radiologic measurements: grade of stenosis and intragraft to systemic systolic blood pressure ratio. These parameters may help determine the frequency of monitoring for recurrent stenosis in a given graft.

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

Natural history of arteriovenous grafts in hemodialysis patients

Most hemodialysis patients in the United States have an arteriovenous graft as their vascular access. Grafts have a relatively short life span and are prone to recurrent stenosis and thrombosis, requiring multiple salvage procedures to maintain their patency. There is little information in the literature regarding the clinical factors that determine graft survival and complications. We evaluated prospectively the outcomes of 256 grafts placed at a single institution during a 2-year period. A salvage procedure to maintain graft patency (thrombectomy, angioplasty, or surgical revision) was required in 29% of the grafts at 3 months, 52% at 6 months, 77% at 12 months, and 96% at 24 months. Thus, primary graft survival (time from graft placement to the first intervention) was only 23% at 1 year and 4% at 2 years. Primary graft survival was significantly less among patients with hypoalbuminemia compared with patients with a normal serum albumin level (P = 0.003). Secondary graft survival (time from graft placement to permanent graft failure) was 65% at 1 year and 51% at 2 years. Neither primary nor secondary graft survival was significantly correlated with patient age, sex, diabetic status, body mass index, or graft site. A mean of 1.22 interventions per graft-year were required to maintain access patency, including 0.51 thrombectomies, 0.54 angioplasties, and 0.17 surgical revisions. In conclusion, hypoalbuminemia is a strong predictor of the requirement for an early graft intervention. Patients with hypoalbuminemia may require a heightened index of suspicion in monitoring their grafts for evidence of stenosis.

Endovascular versus surgical treatment for thrombosed hemodialysis grafts: A prospective, randomized study

PURPOSE

The objective of this study was to compare clinical outcome and costs for two widely used treatment strategies for hemodialysis graft thrombosis.

METHODS

During a 4-year period, 80 patients with thrombosed dialysis grafts were randomly assigned to surgical thrombectomy with or without graft revision (SURG) or thrombolytic therapy with urokinase with the pulse-spray technique (ENDO), with adjunctive percutaneous transluminal angioplasty as indicated. All the procedures were performed in an endovascular operating suite with fistulography. The clinical and cost data were tabulated, and the outcome was analyzed with the life-table method.

RESULTS

Fifty-six women and 24 men ranged in age from 33 to 90 years (mean, 63.7 years). The patients had undergone a mean of 2.8 prior access procedures in the ipsilateral extremity. All the grafts were upper extremity expanded polytetrafluoroethylene grafts. Lesions that were presumed to be the primary cause of graft thrombosis were identified in 73 of 80 grafts, and 60 of these were at the venous anastomosis. The procedure time averaged 99 minutes for the patients in the SURG group and 113 minutes for the patients in the ENDO group (P =.12). Eleven patients in the ENDO group crossed over to surgical revision as compared with two patients in the SURG group who required adjunctive percutaneous transluminal angioplasty (P =.005). The mean cost of treatment (including room and supply costs but not professional fees) was significantly higher for the ENDO group than for the SURG group ($2945 vs $1512; P <.001). There were no procedure-related complications in either group. At a median follow-up time of 24 months, there was no difference in primary or assisted primary patency between groups, which averaged 6 and 7 months, respectively.

CONCLUSION

Although thrombolytic therapy combined with endovascular treatment can extend the life of dialysis grafts with results similar to surgical revision, there is a high rate of technical failure necessitating surgery and a substantially higher cost for thrombolysis.

Prophylactic angioplasty reduces thrombosis in virgin ePTFE arteriovenous dialysis grafts with greater than 50% stenosis: subset analysis of a prospectively randomized study

PURPOSE

To determine if prophylactic percutaneous transluminal balloon angioplasty (PTA) can extend patency in functioning virgin ePTFE arteriovenous hemodialysis grafts.

MATERIALS AND METHODS

The results of a prospectively randomized study of 64 patients with greater than 50% stenosis of functioning ePTFE arteriovenous hemodialysis grafts who were blindly assigned to be treated with PTA (treatment group) or observed without treatment (control group) were subjected to statistical subset analysis. Within this group were 21 patients (virgins) who had never undergone surgery, PTA, or thrombolysis. Eight patients had been assigned to the treatment group and 13 to the control group. The virgin groups were well matched as to age, sex, and risk factors. The virgin treatment group versus virgin control group had 1.63 versus 1.46 stenoses per patient and 61.3% versus 63.3% average percentage stenosis per lesion, respectively. Stenoses were treated with PTA 27 times (average, 3.4 per patient) in the virgin treatment group. Primary study patency began at the time of randomization and ended with graft thrombosis or nonfunction.

RESULTS

Among the 32 patients randomized to treatment with PTA, study patency was significantly increased (P > .0001) and the incidence of graft thrombosis significantly decreased (P = .0151) in the eight-patient virgin subset when compared with the 24-patient nonvirgin subset of the treatment group. During the 81.3 patient-dialysis-year study period, patency in the virgin-treatment versus virgin-control groups, respectively, was terminated by thrombosis in two versus nine, by death in two versus two, and cadaveric renal transplant in one versus zero. There was a statistically significant prolongation of study patency (P = .0349) and a reduction of graft thromboses, 0.10 versus 0.44 thromboses per patient-dialysis year, in the virgin-treatment group compared to the virgin-control group.

CONCLUSION

Patency after PTA of ePTFE hemodialysis grafts is significantly affected by previous interventions. Prophylactic PTA of stenoses greater than 50% in functioning virgin ePTFE arteriovenous hemodialysis grafts can significantly extend their patency. PTA should be included as an important treatment option in this patient population.