Treatment of hemodialysis-related central venous stenosis or occlusion: results of primary Wallstent placement and follow-up in 50 patients

Three-dimensional gadolinium-enhanced MR venography to evaluate central venous steno-occlusive disease in hemodialysis patients

AIM

To determine the agreement and diagnostic accuracy of three-dimensional gadolinium-enhanced magnetic resonance venography (3D-Gd-MRV) in central venous steno-occlusive disease (CVSD) in haemodialysis patients.

MATERIALS AND METHODS

Fourteen consecutive haemodialysis patients underwent interventional procedures to evaluate or treat CVSD. 3D-Gd-MRV was performed before the procedures and the results were compared with digital subtraction angiography (DSA).

RESULTS

DSA showed >50% stenosis in all 14 patients, 13 of whom were diagnosed correctly using 3D-Gd-MRV. Moderate stenosis was missed at 3D-Gd-MRV in one case whereby the indwelling dialysis central venous catheter may have caused an artefact on the images and hindered the accuracy of the result. The sensitivity of 3D-Gd-MRV in revealing stenosis was 93% (13/14). No complications caused by contrast agent toxicity occurred in any patient.

CONCLUSION

3D-Gd-MRV employing a non-breath-hold technique is highly sensitive in the diagnosis of CVSD and may be an alternative technique to DSA for the visualization of central veins.

Use of covered stents in the central vein: a feasibility study in a canine model

PURPOSE

To evaluate the feasibility of using covered stents vs. bare stents in a model of central vein stenosis with an arteriovenous graft created to mimic the conditions in hemodialysis patients.

METHODS

In 7 mongrel dogs, an expanded polytetrafluoroethylene-covered nitinol stent was placed in one common iliac vein and a bare stent was placed in the contralateral vein. Arteriovenous grafts were created bilaterally between the common femoral artery and vein to induce endothelial damage. Neointima formation in the covered stents was compared to the bare stents at 12 weeks using microscopy and histochemical staining.

RESULTS

Two dogs were excluded due to thrombosis and infection of the arteriovenous grafts, but all stents in the remaining 5 dogs were patent. Smooth, complete neointimal coverage was observed on the inner surface of all the covered stents without intraluminal thrombus. In contrast, incomplete neointimal coverage was seen in all bare stents, with small focal thrombi adhering to the neointima on 3 bare stents. Focal nodular neointimal hyperplasia with denudation of the endothelium was observed in only 2 bare stents. Mean neointimal thickening was significantly greater in the covered stents. Eccentric neointimal thickening was observed at the inflow and outflow segments of both types of stents.

CONCLUSION

Covered stents are technically feasible for the treatment of central vein stenosis, and they demonstrate complete, smooth neointimal coverage in normal central veins, but they also display greater neointimal thickening than bare stents.

The primary patency of percutaneous transluminal angioplasty in hemodialysis patients with vascular access failure

Background and Objectives

Dysfunction of arteriovenous fistulas (AVFs) and arteriovenous grafts (AVGs) contributes significantly to morbidity and hospitalization in the dialysis population. We evaluated the primary patency of AVFs following percutaneous transluminal angioplasty (PTA) in haemodialysis patients.

Subjects and Methods

We performed 231 interventions in 118 patients with a mean age of 62.1±12.9 years. We performed 122 interventions in 53 AVG patients (44.9%), and 109 interventions in 65 AVF patients (55.1%). If there was thrombosis of the vascular access, urokinase was administered and/or thrombus aspiration was performed. The stent was inserted when balloon dilatation did not expand sufficiently or elastic recoil occurred.

Results

For the 118 patients, the median patency time was 10.45±10.29 months at 92 months of follow-up. The primary patencies for stenotic AVFs at 6, 12, 24, 36, 48, and 60 months were 63.4%, 41.4%, 17.0%, 9.7%, 7.3%, and 2.4%, respectively. The primary patencies for AVGs at 6, 12, 24, and 36 months were 36.9%, 19.5%, 10.8%, 2.1%, respectively, and were obtained by means of the Kaplan-Meier analysis (log rank=6.42, p<0.05). The median patency time was 11.0 months and 4.45 months in the non-thrombus and thrombus groups, respectively. The complication rate was 1.73% (4/231); two cases of pseudoaneurysms and two cases of extravasation were detected. All therapy failures (5/231) occurred in thrombotic lesions of AVGs and were treated surgically.

Conclusion

PTA is an efficacious method for the correction of stenosis of AVFs for hemodialysis, thus prolonging the patency of the fistulas.

Stenting of the superior vena cava and left brachiocephalic vein with preserving the central venous catheter in situ

Stenting of the central veins is well established for treating localized venous stenosis. The techniques regarding catheter preservation for central venous catheters in the superior vena cava have been described. We describe here a method for stent implantation in the superior vena cava and the left brachiocephalic vein, and principally via a single jugular venous puncture, while saving a left sided jugular central venous catheter in a patient suffering from central venous stenosis of the superior vena cava and the left brachiocephalic vein.

Long-term results of stent-graft placement to treat central venous stenosis and occlusion in hemodialysis patients with arteriovenous fistulas

PURPOSE

To determine the effectiveness of stent-grafts for the treatment of central venous disease in hemodialysis patients with functioning arteriovenous (AV) fistulas.

MATERIALS AND METHODS

Between October 2004 and March 2010, 42 VIABAHN stent-grafts were deployed in central veins of 30 patients (16 men, 14 women; mean age 60 y) with functioning AV fistulas and central venous disease that did not respond to percutaneous transluminal angioplasty (PTA). Eighteen patients had central vein stenosis and 12 had occlusion. Previous PTA and/or bare metal stent placement had been performed in 23 patients (77%). Surveillance was carried out at 3, 6, 9, 12, 18, and 24 months with diagnostic fistulography. The mean follow-up was 705 days (range, 66-1,645 d). Statistical analysis included Kaplan-Meier and log-rank studies.

RESULTS

Technical success rate was 100%. Primary patency rates were 97%, 81%, 67%, and 45% at 3, 6, 12, and 24 months, respectively. Primary assisted patency rates were 100%, 100%, 80%, and 75% at 3, 6, 12, and 24 months, respectively. Patients without previous procedures had significantly shorter times to repeat intervention (P = .018) than those who had undergone PTA or bare metal stent placement previously. Patients with occlusive lesions had a significantly shorter primary patency interval (P = .05) than patients with stenoses. Occluded veins were more likely to require further stent-grafts (P = .02). Twelve patients required further stent-grafts to maintain patency. There was one minor complication.

CONCLUSIONS

Stent-graft placement to treat central venous disease in hemodialysis patients with autogenous AV fistulas is safe and effective if PTA fails to maintain luminal patency.

Sharp Needle Recanalization for Salvaging Hemodialysis Accesses with Chronically Occluded Peripheral Outflow

Purpose

To assess the effectiveness of sharp needle recanalization (SNR) for treatment of chronically occluded venous outflow in hemodialysis access.

Methods

A retrospective analysis of patient records from January 2006 to March 2010 was conducted. Forty-four hemodialysis patients (31 fistulas, 13 grafts) were referred for arm swelling (18%), excessive bleeding after dialysis (29%), and thrombosis (53%). All patients had chronic occlusion of the outflow vein which failed conventional recanalization techniques. A new outflow pathway was established by advancing a 21g needle and dilating the subcutaneous tract to bridge the fistula body to a juxtaposed patent vein. If necessary, uncovered or covered stents were utilized to maintain patency of the newly formed subcutaneous tract.

Results

Forty-four patients underwent 45 SNR procedures, with restoration of normal function and complete relief of symptoms in 40 (91%) patients. The average tract length was 15 mm (range, 1 to 32) and the average dilatation diameter was 8 mm. During the initial SNR procedure, bare metal (n=21) or covered (n=5) stents were inserted in 26 patients. The average follow-up was 18.4 months (range, 0.2 to 48 months). No major complications were observed with the procedure. At 12 months, the primary access, primary tract, and secondary access patencies were 10%, 51%, and 92%, respectively. Percutaneous thrombectomy procedures were performed at a rate of 1.16 per access-year and the number of interventions within the tract was 0.94 per access-year.

Conclusions

Sharp needle recanalization is an effective percutaneous treatment for restoring function to hemodialysis accesses with chronically occluded venous outflow pathways.

Efficacy of covered stent placement for central venous occlusive disease in hemodialysis patients

OBJECTIVES

Covered stents have been proposed as an endovascular option for recalcitrant cases of hemodialysis-related central venous occlusive disease (CVOD). This study evaluated the efficacy and durability of covered stents in treating CVOD to preserve a functional dialysis access circuit.

METHODS

A retrospective review was performed of all patients with clinically significant CVOD who were treated by placement of covered stents from April 2007 to September 2010. Demographics, lesion locations and anatomic characteristics, stent graft, and access patency rates were determined. Complications, reinterventions, and factors influencing their outcomes were examined.

RESULTS

In 25 patients (56% men; mean age, 57 ± 29 years) with CVOD, covered stents were used in 20 to treat symptomatic venous hypertension or in 5 at the time of access creation to enable functionality. The target lesion was accessed via the dialysis access site or the common femoral vein. The Viabahn endoprosthesis (W. L. Gore and Associates, Flagstaff, Ariz) was used in 24 patients (average size and length, 11 mm × 5 cm) and a 13-mm × 5-cm Fluency covered stent (Bard Peripheral Vascular, Tempe, Ariz) was implanted in 1 patient. Technical success was 100%, and resolution of arm edema occurred after covered stent deployment in symptomatic patients. Two postprocedural cases (8%) of thrombosis occurred, one within 30 days and another at 3 months. Both required percutaneous thrombectomy and percutaneous transluminal angioplasty (PTA). Three additional patients (12%) required PTA due to restenosis in one of the ends of the device. Covered stent primary patency (PP), assisted primary patency (APP), and secondary patency (SP) were 56%, 86%, and 100% at 12 months, respectively. Access patency rates at 12 months were 29%, 85%, and 94% for PP, APP, and SP, respectively, in patients that received a covered stent for access salvage; patency rates were 74%, 85%, and 94% for PP, APP, and SP, respectively, in patients in whom the access was created after the venous outflow restoration.

CONCLUSIONS

Placement of covered stents for hemodialysis-related CVOD is safe, effective in relieving symptoms, and enabled functionality of new dialysis access circuits. Further prospective and randomized studies are necessary to determine whether covered stents provide superior long-term results to those achieved with PTA and bare metal stents.

Revascularization of a central vein total occlusion via antegrade and retrograde approach in a patient with hemodialysis access

The occurrence of central vein total occlusion results in upper arm edema, pain, and hemodialysis access failure in uremic patient. Previous studies have proven the effectiveness of percutaneous balloon angioplasty for central vein total occlusion. Here, we report a rare case of successful revascularization of central vein total occlusion via antegrade and retrograde approach.

Central venous disease in hemodialysis patients: prevalence, etiology and treatment

A common problem in the management of hemodialysis patients is central venous occlusive disease. There has been extensive literature on the treatment of this important and prevalent problem. Treatment options to date include percutaneous balloon angioplasty, bare metal stents and surgical bypass. Unfortunately, all the available treatment options have poor long-term patency, requiring repetitive intervention. More recently, covered stents have been mentioned in the literature for the treatment of central venous stenosis and obstruction. There is very little data to date on this technology, and further randomized controlled trials will be needed to compare the efficacy of percutaneous balloon angioplasty, bare metal stents and covered stents. It appears prevention of this difficult problem is paramount, by limiting venous access or intervention of the central venous system.

Review of central venous disease in hemodialysis patients

A common problem in the management of patients who are undergoing hemodialysis is central venous occlusive disease. There has been extensive literature on the treatment of this important and prevalent problem. Treatment options to date include percutaneous balloon angioplasty, bare metal stents, and surgical bypass. Unfortunately, all the available treatment options have poor long-term patency, requiring repeated interventions. More recently, covered stents have been mentioned in the literature for the treatment of central venous stenosis and obstruction. There are very few data to date on this technology, and further randomized controlled trials will be needed to compare the efficacy of percutaneous balloon angioplasty, bare metal stents, and covered stents. It appears that it is of paramount importance to prevent this difficult problem by limiting access to, or intervention in, the central venous system.

Patency rates for angioplasty in the treatment of pacemaker-induced central venous stenosis in hemodialysis patients: results of a multi-center study

While hemodialysis access ligation has been used to manage pacemaker (PM) and implantable cardioverter-defibrillator (ICD) lead-induced central venous stenosis (CVS), percutaneous transluminal balloon angioplasty (PTA) has also been employed to manage this complication. The advantages of PTA include minimal invasiveness and preservation of arteriovenous access for hemodialysis therapy. In this multi-center study we report the patency rates for PTA to manage lead-induced CVS. Consecutive PM/ICD chronic hemodialysis patients with an arteriovenous access referred for signs and symptoms of CVS due to lead-induced CVS were included in this analysis. PTA was performed using the standard technique. Technical and clinical success was examined. Technical success was defined as the ability to successfully perform the procedure. Clinical success was defined as the ability to achieve amelioration of the signs and symptoms of CVS. Both primary and secondary patency rates were also analyzed. Twenty-eight consecutive patients underwent PTA procedure. Technical success was 95%. Postprocedure clinical success was achieved in 100% of the cases where the procedure was successful. The primary patency rates were 18% and 9% at 6 and 12 months, respectively. The secondary patency rates were 95%, 86%, and 73% at 6, 12, and 24 months, respectively. On average, 2.1 procedures/year were required to maintain secondary patency. There were no procedure-related complications. This study finds PTA to be a viable option in the management of PM/ICD lead-induced CVS. Additional studies with appropriate design and sample size are required to conclusively establish the role of PTA in the management of this problem.

Central vein stenosis: current concepts

Central vein stenosis (CVS) is a common complication of the central venous catheter (CVC) placement. The prevalence of CVS has mostly been studied in those who present with symptoms such as swelling of the extremity, neck and breast. CVS compromises arteriovenous access and can be resistant to treatment. A previous history of CVC placement is the most important risk factor for the development of CVS later. Pacemaker and defibrillator wires are associated with a high incidence of CVS. Increasingly liberal use of peripherally inserted central catheters (PICC) is likely to increase the incidence of CVS. The trauma and inflammation related to the catheter placement is thought to result in microthrombi formation, intimal hyperplasia and fibrotic response, with development of CVS. Treatment of CVS by endovascular procedures involves angioplasty of the stenosis. An elastic or recurrent stenosis may require a stent placement. The long-term benefits of the endovascular procedures, although improved with newer technology, remain modest. Surgical options are usually limited. Future studies to explore the pathogenesis and the use of novel therapies to prevent and treat CVS are needed. The key to reducing the prevalence of CVS is in reducing CVC placement and placement of arteriovenous accesses prior to initiating dialysis. Early referral of the patients to the nephrologists by the primary care physicians is important. Timely vein mapping and referral to the surgeon for fistula creation can obviate the need for a CVC and decrease incidence of CVS.

Tunneled dialysis catheters: recent trends and future directions

Despite aggressive efforts to increase autogenous fistula prevalence primarily from recommendations by the NKF and the Fistula First National Vascular Access Improvement Initiative, catheters remain an essential access modality for a large percentage of the hemodialysis population. Tunneled dialysis catheters or chronic catheters are associated with a multitude of complications including infections, stenosis, thrombosis, and increased morbidity and mortality even after adjustment for potential confounding variables. Also, given the blood flow rates of catheters, dialysis adequacy is compromised as compared with arteriovenous fistulae and arteriovenous grafts. This review endeavors to provide an update on catheter outcomes in the Fistula First and Kidney Disease Outcomes Quality Initiative era in relation to the increasing fistula prevalence and decline in graft placements. The conflicting view of whether catheters are increasing concurrently with the increase in fistula prevalence is discussed. The management of tunneled dialysis catheter-related complications is considered with a review of the most recent data. Future research strategies and innovations in catheter design are also addressed. This review provides a comprehensive update of tunneled hemodialysis catheters, their necessity and pitfalls, and novel directions for future investigation.

Central venous obstruction management

A major challenge in the management of hemodialysis patients is central venous stenosis and obstruction. Placement of central venous catheters has been shown to result in a high incidence of central venous stenosis or obstruction. There has been extensive literature on the treatment of this important and prevalent problem. Treatment options include percutaneous balloon angioplasty and bare metal stents. Unfortunately, all the available treatment options have variable rates of patency, requiring repeated intervention. More recently, covered stents have been mentioned in the literature for the treatment of central venous stenosis and obstruction. There is very little data to date, and further randomized controlled trials will be needed to compare the efficacy of percutaneous balloon angioplasty, bare metal stents, and covered stents. It appears prevention of this difficult problem is paramount, by limiting use of central venous catheters.

Stent placement in hemodialysis access: historical lessons, the state of the art and future directions

Vascular access stenosis in patients undergoing chronic hemodialysis is a major issue that is associated with increased morbidity, mortality, and cost of medical care. Recent data have emphasized that endovascular stents could be used in the treatment of central as well as peripheral stenotic lesions. In general, a peripheral or central vein lesion that is elastic or recurs within a three-month period after an initially successful balloon angioplasty or a stenosis where surgical revision is not possible are some indications for intravascular stent placement. Recent reports have expanded the role of stents in the management of pseudoaneurysms associated with dialysis access. In this context, the utilization of these devices must take into account a fair comparison with the traditional (surgical) approaches regarding effectiveness as well as costs. This report describes the role of stents in arteriovenous dialysis access. In addition, some of the recent advances in the structure and complicating issues such as stent fracture, migration, and infection, as well cannulation through the stent, are discussed.

Percutaneous treatment of central venous stenosis in hemodialysis patients: long-term outcomes

The purpose of this study was to evaluate the long-term outcomes of endovascular treatment of central venous stenosis in patients with arteriovenous fistulas (AVFs) for hemodialysis. Five hundred sixty-three patients with AVFs who were referred for a fistulogram were enrolled in this study. Among them, 44 patients showed stenosis (n = 35) or occlusions (n = 9) in the central vein. For the initial treatment, 26 patients underwent percutaneous transluminal angioplasty (PTA) and 15 patients underwent stent placements. Periods between AVF formation and first intervention ranged from 3 to 144 months. Each patient was followed for 14 to 60 months. Procedures were successful in 41 of 44 patients (93.2%). Primary patency rates for PTA at 12 and 36 months were 52.1% and 20.0%, and assisted primary patency rates were 77.8% and 33.3%, respectively. Primary patency rates for stent at 12 and 36 months were 46.7% and 6.7%, and assisted primary patency rates were 60.0% and 20.0%, respectively. Fifteen of 26 patients with PTAs underwent repeated interventions because of restenosis. Fourteen of 15 patients with a stent underwent repeated interventions because of restenosis and combined migration (n = 1) and shortening (n = 6) of the first stent. There was no significant difference in patency between PTAs and stent placement (p > 0.05). Average AVF patency duration was 61.8 months and average number of endovascular treatments was 2.12. In conclusion, endovascular treatments of central venous stenosis could lengthen the available period of AVFs. There was no significant difference in patency between PTAs and stent placement.

[Venous interventions. Part 2: Thromboses of the upper torso and mesenteric veins]

This article focuses on the percutaneous treatment options of venous thromboses and occlusions. Interventional therapy modalities for mediastinal, brachial, axillar, cerebral, and mesenteric thromboses are reviewed. Stenoses of the superior vena cava are most often caused by mediastinal malignomas. Balloon angioplasty together with stent implantation is an effective method for revascularisation in cases of upper venous congestion. Benign central venous stenoses are common in dialysis patients for whom interventional therapy using balloon angioplasty has proven excellent results. In the treatment of insufficient dialysis access, percutaneous techniques represent the first-choice option. Regarding cerebral and mesenteric thrombosis, interventional therapy is restricted to selected individual cases.

Placement of a catheter through the struts of a previously placed stent for maintenance hemodialysis: a case report

Venous accesses for hemodialysis are beset with thrombosis and stenosis, often resulting in loss of central venous access. We report a case in which an alternate access was created by placement of hemodialysis catheter into the central vasculature by penetrating a stent previously placed in the stenosed right brachio-cephalic vein. To our knowledge, this is the first such report.

Intravascular ultrasound-guided central vein angioplasty and stenting without the use of radiographic contrast agents

Patients with contraindications to iodinated radiographic contrast agents present a significant challenge during endovascular intervention. A 46-year-old man with end-stage renal disease and a normally functioning left upper extremity arteriovenous fistula presented with severe left arm edema. The patient's history included repeated severe anaphylactoid reactions with severe respiratory distress upon exposure to iodinated contrast. In an attempt to avoid the use of iodinated contrast, angioplasty and stent placement of a severe central venous stenosis were performed using only fluoroscopy and intravascular sonography. In patients unable to receive iodinated contrast secondary to anaphylactoid reactions, intravascular sonography can be used to guide angioplasty and stenting of central venous stenosis.

Formation of downhill esophageal varices as a rare but serious complication of hemodialysis access: a case report and comprehensive literature review

BACKGROUND

Proximal or "downhill" esophageal varices are a rare complication of superior vena caval (SVC) obstruction. Few reports describe downhill varices in dialysis patients with catheter-related SVC occlusion.

METHODS

We studied a case of downhill esophageal varices in a dialysis patient from our center and reviewed the published literature on presentation, evaluation and treatment in other dialysis patients (MEDLINE database search).

RESULTS

Including our current case, we identified eight reports of dialysis patients with downhill varices. All cases were recognized after presentation with gastrointestinal bleeding, in contrast to low reported bleeding rates of downhill varices in non-dialysis patients. Localized edema and superficial venous engorgement (signs of SVC occlusion) were each observed in four of eight patients. The duration of hemodialysis dependence ranged from 2.5 to 23 years, and dialysis access history included multiple central venous catheters when described (seven cases). Central venous imaging by direct, magnetic resonance or computerized tomographic venography documented SVC stenosis in all cases. Management included percutaneous transluminal angioplasty of the SVC with or without stenting in five of eight patients, three of whom developed restenosis during observation. Successful surgical venous bypass was performed in one patient after failed percutaneous venoplasty. Varices were treated with band ligation in four of eight cases without reported complications.

CONCLUSIONS

Although rare, downhill esophageal varices should be considered in the differential diagnosis of upper gastrointestinal hemorrhage in dialysis patients exposed to central venous catheters. Diagnosis should prompt radiographic evaluation of SVC patency. Treatment requires timely and coordinated care by specialists in endovascular interventions and gastrointestinal endoscopy.

Migration of superior vena cava stent

There has been a recent increase in the use of endovascular prostheses resulting in complex surgical and interventional complications not previously recognised. We report a case of Superior vena cava stenosis treated with a wallstent which migrated to the right atrium, necessitating a combined radiological and surgical approach to retrieve it.

Use of nitinol stents following recanalization of central venous occlusions in hemodialysis patients

PURPOSE

To retrospectively review the patency of endovascular interventions with nitinol stent placement for symptomatic central venous occlusions in hemodialysis patients.

METHODS

A retrospective review of all patients who underwent endovascular interventions for dysfunctional hemodialysis grafts and fistulas was performed from April 2004 to August 2006. A total of 6 patients presented with arm and/or neck and facial swelling and left brachiocephalic vein occlusion. The study group consisted of 3 men and 3 women with a mean age of 79.5 years (SD 11.2 years). Of these 6 patients, 1 had a graft and 5 had fistulas in the left arm. The primary indication for nitinol stent placement was technical failure of angioplasty following successful traversal of occluded central venous segments. Patency was assessed from repeat fistulograms and central venograms performed when patients redeveloped symptoms or were referred for access dysfunction determined by the ultrasound dilution technique. No patients were lost to follow-up.

RESULTS

Nitinol stent placement to obtain technically successful recanalization of occluded venous segments was initially successful in 5 of 6 patients (83%). In 1 patient, incorrect stent positioning resulted in partial migration to the superior vena cava requiring restenting to prevent further migration. Clinical success was observed in all patients (100%). Over the follow-up period, 2 patients underwent repeat intervention with angioplasty alone. Primary patency was 83.3% (95% CI 0.5-1.2) at 3 months, and 66.7% at 6 and 12 months (0.2-1.1, 0.1-1.2). Secondary patency was 100% at 12 months with 3 patients censored over that time period. Mean primary patency was 10.4 months with a mean follow-up of 12.4 months. No complications related to recanalization of the occluded central venous segments were observed.

CONCLUSION

Our initial experience has demonstrated that use of nitinol stents for central venous occlusion in hemodialysis patients is associated with good mid-term patency and may exceed historical observations with prior use of Wallstents.

Long-term outcomes of primary angioplasty and primary stenting of central venous stenosis in hemodialysis patients

INTRODUCTION

Central (superior vena cava, brachiocephalic, or subclavian) venous stenoses are a major impediment to long-term arteriovenous access in the upper extremities. The optimal management of these stenoses is still undecided. The purpose of this study was to determine the outcomes of primary angioplasty (PTA) vs primary stenting (PTS) in a dialysis access population at a tertiary referral academic medical center.

METHODS

A database of consecutive hemodialysis patients undergoing endovascular treatment for central venous stenosis was developed for the period 1995 through 2003. This database was retrospectively reviewed. Vessels exposed to either primary high-pressure balloon angioplasty or primary stenting were examined. Vessels undergoing stenting after failed or suboptimal angioplasty were defined as failures at the time of stenting despite the potential continued patency upon completion of stenting. Kaplan-Meier survival analyses were performed to assess time-dependent outcomes. Cox proportional hazards analysis was performed for time-dependent variables. Data are presented as mean +/- standard deviation where appropriate.

RESULTS

PTS was used to treat 26 patients (35% male; average age, 57 +/- 15 years) with 26 central venous stenoses, and 47 patients (45% male; average age, 57 +/- 18 years) with 49 central venous stenoses were treated with PTA. The PTS group underwent 71 percutaneous interventions per stenosis (average, 2.7 +/- 2.4 interventions), and the PTA group underwent 98 interventions per stenosis (average, 2.0 +/- 1.6 interventions). The PTS group hemodialysis access site was an average of 1.0 +/- 1.3 years old at the time of the initial intervention, and the hemodialysis access in the PTA group was an average of 1.1 +/- 1.2 years old. Primary patency was equivalent between groups by Kaplan-Meier analysis, with 30-day rates of 76% for both groups and 12-month rates of 29% for PTA and 21% for PTS (P = .48). Assisted primary patency was also equivalent (P = .08), with a 30-day patency rate of 81% and 12-month rate of 73% for the PTA group, vs PTS assisted patency rates of 84% at 30 days, and 46% at 12 months. Ipsilateral hemodialysis access survival was equivalent between groups.

CONCLUSIONS

Endovascular therapy with PTA or PTS for central venous stenosis is safe, with low rates of technical failure. Multiple additional interventions are the rule with both treatments. Although neither offers truly durable outcomes, PTS does not improve on the patency rates more than PTA and does not add to the longevity of ipsilateral hemodialysis access sites.

Central vein stenosis: a nephrologist's perspective

Central vein stenosis is commonly associated with placement of central venous catheters and devices. Central vein stenosis can jeopardize the future of arteriovenous fistula and arteriovenous graft in the ipsilateral extremity. Occurrence of central vein stenosis in association with indwelling intravascular devices including short-term, small-diameter catheters such as peripherally inserted central catheters, long-term hemodialysis catheters, as well as pacemaker wires, has been recognized for over two decades. Placement of multiple catheters, longer duration, location in subclavian vein, and placement on the left-hand side of neck seem to predispose to the development of central vein stenosis. Endothelial injury with subsequent changes in the vessel wall results in development of microthrombi, smooth muscle proliferation, and central vein stenosis. Central vein stenosis is often asymptomatic in nondialysis patients, but can result in edema of ipsilateral extremity and breast when challenged by increased flow from an arteriovenous fistula or arteriovenous graft. Bilateral central vein stenosis or superior vena cava stenosis can produce a clinical picture of superior vena cava syndrome, associated with engorgement of face and neck. Endovascular interventions are the mainstay of management of central vein stenosis. Percutaneous angioplasty and stent placement for elastic and recurring lesions can restore the functionality of the vascular access, at least temporarily. Frequent or multiple interventions are usually required. In recalcitrant cases, surgical bypass of the obstruction is an option. In resistant cases with severe symptoms, occlusion of the functioning vascular access will usually provide relief of symptoms. Further study of mechanisms of development of central vein stenosis and search for a targeted therapy is likely to lead to better ways of managing central vein stenosis. Prevention of central vein stenosis is the key to avoid access failure and other complications from central vein stenosis and relies upon avoidance of central vein stenosis placement and timely placement of arteriovenous fistula in prospective dialysis patient.

Stent fracture in the left brachiocephalic vein

A 68-year-old male hemodialysis patient presented with severe congestion in his left arm. Left arm venography showed a completely occluded left brachiocephalic vein. We chose a self-expandable stent for treating this vein. However, restenosis occurred once at 8 months and again after six additional months. The cause of the restenosis was considered to be a stent fracture. On the first restenosis, we performed redilation with a balloon; on the second restenosis, we chose stent-in-stent with a balloon-expandable stent. At least 9 months after the stent-in-stent procedure, there has been no edema in his left arm. Therefore, stent-in-stent is one of the useful strategies for stent fracture in central venous obstruction.

Patency of Endovascular Treatment for Central Venous Stenosis: Is There a Difference Between Dialysis Fistulas and Grafts?

PURPOSE

To determine if there is a difference in intervention patency for central venous stenosis (CVS) and occlusion between patients with autogenous hemodialysis fistulas and those with grafts.

MATERIAL AND METHODS

A retrospective study was performed from March 1998 to September 2005 identifying all patients with autogenous fistulas and synthetic grafts who underwent percutaneous angioplasty and/or stent placement for CVS. This study cohort consisted of 38 patients (22 with fistulas and 16 with grafts). Age, sex, type of access, location and side of the access, location and side of the CVS, presence of diabetes, previous hemodialysis catheter placement, date and type of interventions, and outcomes were recorded. The patency of each intervention was estimated by using the Kaplan-Meier survival curves. Univariate and multivariate analysis of the variables were performed.

RESULTS

Eighty-nine interventions were performed; 83 were angioplasties and six were stent placements. Previous catheter placement on the side of the CVS occurred in 29 of the 38 patients (76%). Technical and clinical success of the interventions were 93.3% and 94.4% respectively. The intervention or primary patency rates +/- standard errors at 3, 6, and 9 months in the fistula group were 88.5% +/- 4.8, 59.4% +/- 7.6, and 46% +/- 7.9, respectively. In the graft group, the rates were 78.1% +/- 7.3, 40.7% +/- 9, and 16% +/- 7.3, respectively. With multivariate analysis, intervention patency remained significantly longer for fistulas (P .014) and in patients who did not have a previous catheter (P .001).

CONCLUSION

Longer intervention-free survival for CVS was observed in patients with autogenous fistulas compared with grafts and in patients who did not previously undergo hemodialysis catheter insertion.

Effect of Secondary Interventions on Patency of Vascular Access Sites for Hemodialysis

PURPOSE

To determine the impact of secondary procedures performed to maintain arteriovenous fistula (AVF) and arteriovenous graft (AVG) patency.

METHODS

There hundred and eighty six vascular access procedures were retrospectively evaluated. 156 (40.4%) patients required radiological interventions to treat acute thrombosis, swelling of the extremity with the access site, insufficient hemodialysis, or stenosis at an anastomotic site.

RESULTS

The 386 cases comprised 106 AVGs and 280 AVFs. In 138 of the 156 cases, which required a radiological intervention, the treatment was successful and saved the vascular access site. The unassisted post-intervention patency time for these 138 successful cases was 13.1 +/- 12 months (range, 1-65 months). Twenty-nine (63%) of the 46 access sites treated with surgical thrombectomy were saved.

CONCLUSIONS

Frequent, regular follow-up of hemodialysis patients with vascular access sites is the best way to diagnose problems early and allow the best chance of long-term function.

N, Tarasconi DP. Tratamento endovascular da síndrome da veia cava superior: relato de caso e revisão da literatura

Relatamos o caso de uma paciente portadora de síndrome da veia cava superior sintomática de origem benigna tratada pela técnica endovascular. A angiorressonância magnética pré-angioplastia evidenciou extensa trombose do tronco braquiocefálico esquerdo, da veia subclávia esquerda e obstrução da veia cava superior junto ao tronco braquiocefálico direito. A paciente realizou mastectomia radical 2 anos antes, associada à quimioterapia e radioterapia do tórax. Foram realizados angioplastia venosa e implante de stent expansível por balão. O resultado foi satisfatório, com alívio imediato dos sintomas devido à recanalização da veia cava superior e do tronco braquiocefálico direito. Foi instituída anticoagulação oral. A paciente permanece sem recidiva dos sintomas após 8 meses de acompanhamento. O tratamento endovascular é uma alternativa terapêutica com baixa morbidade e resultado satisfatório a médio prazo que pode ser oferecida aos pacientes portadores de síndrome da veia cava superior.

Radiological Intervention to Maintain Vascular Access

Stenoses and thromboses of dialysis grafts and fistulae are common problems in patients with end stage renal disease (ESRD). Timely recognition and treatment of access-related complications are essential to achieve long-term access function. Minimally invasive percutaneous interventions are techniques of growing importance for the interventional community. While stenoses can typically be treated by balloon angioplasty (PTA), thrombotic lesions may necessitate the combination of mechanical devices and/or thrombolytic agents with ancillary PTA. In this article, interventional treatments for the failing arteriovenous (AV) access are presented and reviewed.

Central vein obstruction in vascular access

Central venous obstruction has become a major problem because of the frequent need for central venous catheters in haemodialysis patients. This article discusses the epidemiology and clinical features of central venous obstruction and the different surgical and interventional alternatives for its treatment.

Asymptomatic central venous stenosis in hemodialysis patients

PURPOSE

To retrospectively evaluate the natural history of high-grade (>50%) asymptomatic central venous stenosis (CVS) in hemodialysis patients and the outcome of serial treatment of CVS with percutaneous transluminal angioplasty (PTA).

MATERIALS AND METHODS

The institutional review board granted exemption for this retrospective study, the need for informed consent was waived, and all data collection was in compliance with HIPAA. Patients with hemodialysis access requiring maintenance procedures between 1998 and 2004 and incidentally found to have ipsilateral (> or =50%) CVS were identified from a departmental database. Thirty-five patients (19 men, 16 women; mean age, 58.7 years) with 38 grafts met inclusion criteria, and 86 venograms were reviewed. CVS was measured by using venograms obtained before and after PTA, if performed. Patients with arm swelling, multiple CVS, indwelling catheters, and stents at the first encounter were excluded. CVS progression was calculated by dividing the change in the degree of stenosis by the time between venographic examinations. Wilcoxon rank sum test was used to evaluate differences in rate of CVS progression between treated and nontreated patients.

RESULTS

Mean degree of CVS before intervention was 71% (range, 50%-100%). Sixty-two percent (53 of 86) of lesions had associated collateral vessels; 28% (24 of 86) of CVSs were not treated. Mean degree of stenosis in this group was 72% (range, 30%-100%); mean progression was -0.08 percentage point per day. No untreated CVS progressed to symptoms, stent placement, or additional CVS. Seventy-two percent (62 of 86) of CVSs were treated with PTA. Mean degree of stenosis in this group was 74% (range, 50%-100%) before and 40% (range, 0%-75%) after treatment; mean progression was 0.21 percentage point per day after treatment (P = .03). Six (8%) of 62 treatments were followed by CVS escalation; one patient developed arm swelling, four required stents, and four developed additional CVS.

CONCLUSION

PTA of asymptomatic CVS greater than 50% in the setting of hemodialysis access maintenance procedures was associated with more rapid stenosis progression and escalation of lesions, compared with a nontreatment approach.

Placement of Self-expanding Stents with Different Diameters in the Porcine Venous System: An Experimental Study

PURPOSE

To study the vascular histologic response after placement of oversized self-expanding stents in the porcine venous system.

MATERIALS AND METHODS

Twenty-four oversized stents (range of oversizing, 119.5%-216.0%) were deployed in jugular and iliac veins of six miniature pigs divided into two groups with follow-up times of 1 and 3 months. Necropsy with histologic evaluation of each stent was performed, and the areas of neointimal proliferation were calculated with slices obtained during follow-up from each stent at 5 mm from the proximal and distal edges and at the midpoint.

RESULTS

Neointimal proliferation was observed inside the stent lumen. All segments were patent in both groups. However, one jugular stent in the 1-month group and one jugular stent in the 3-month group had migrated at follow-up and were excluded from analysis. There were no significant differences in neointimal growth between the stent edges (proximal and distal) and middle segments of the stents at follow-up in the 1-month group (P = .970) or in the 3-month group (P = .694). Simple linear regression showed strong positive correlation between stent oversizing and neointimal proliferation in the 1-month model (r = 0.791; P < .001) and the 3-month model (r = 0.718; P < .001). There were no significant differences between 1-month and 3-month groups in the degree of neointimal proliferation (P = .072). Also, branched vessels showed no neointimal proliferation at their intersections with the stent-implanted segments.

CONCLUSION

Stent oversizing showed a strong positive correlation with neointimal growth in each follow-up model in this study.

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.

Management of Central Venous Stent Migration in a Patient with a Permanent Inferior Vena Cava Filter

Stent embolization is a rare complication in the treatment of central venous stenoses in patients receiving long-term hemodialysis. The authors report a case of nitinol stent embolization into the right atrium in which the stent could not be repositioned across an indwelling permanent inferior vena cava (IVC) filter. The migrated stent was managed by advancing the stent to the superior margin of the IVC filter and then deploying a second suprarenal IVC filter to prevent repeat embolization.

Central venous stenosis in haemodialysis patients without a previous history of catheter placement

OBJECTIVE

To evaluate dialysis history, imaging findings and outcome of endovascular treatment in six patients with central venous stenosis without a history of previous catheter placement.

MATERIAL AND METHODS

Between April 2000 and June 2004, six (10%) of 57 haemodialysis patients had stenosis of a central vein without a previous central catheter placement. Venography findings and outcome of endovascular treatment in these six patients were retrospectively evaluated. Patients were three women (50%) and three men aged 32-60 years (mean age: 45 years) and all had massive arm swelling as the main complaint. The vascular accesses were located at the elbow in five patients and at the wrist in one patient.

RESULTS

Three patients had stenosis of the left subclavian vein and three patients had stenosis of the left brachiocephalic vein. The mean duration of the vascular accesses from the time of creation was 25.1 months. Flow volumes of the vascular access were very high in four patients who had flow volume measurement. The mean flow volume was 2347 ml/min. One of three patients with brachiocephalic vein stenosis had compression of the vein by the brachiocephalic artery. All the lesions were first treated with balloon angioplasty and two patients required stent placement on long term. Number of interventions ranged from 1 to 4 (mean: 2.1). Symptoms resolved in five patients and improved in one patient who had a stent placed in the left BCV.

CONCLUSION

Central venous stenosis in haemodialysis patients without a history of central venous catheterization tends to occur or be manifested in patients with a proximal permanent vascular access with high flow rates. Balloon angioplasty with or without stent placement offers good secondary patency rates in mid-term.