Impact of COVID-19 pandemic on hemodialysis access thrombosis

BACKGROUND

Delay in care of suspected stenosis or thrombosis can increase the chance of losing a functioning hemodialysis access. Access to care and resources were restricted during the COVID-19 pandemic. To evaluate the impact of the pandemic on arteriovenous fistula (AVF) and arteriovenous graft (AVG) procedures we have assessed the number and success of thrombectomies done before and during the COVID-19 pandemic.

METHODS

We examined all AVF and AVG angiograms with and without interventions, including thrombectomies, performed at a single center during April 2017-March 2021 (pre-COVID-19 era) and April 2020-March 2021 (COVID-19 era).

RESULTS

The proportion of procedures that were thrombectomies was higher during the COVID-19 era compared to the pre-COVID-19 era (13.3% vs 8.7%, p = 0.009). The proportion of thrombectomy procedures was higher during COVID-19 for AVF (8.2% vs 3.0%, p < 0.001) but there was no difference for AVG (26.5% vs 27%, p = 0.99). There was a trend toward a higher likelihood of unsuccessful thrombectomy during COVID-19 (33.3% vs 20.4%, p = 0.08).

CONCLUSIONS

More dialysis access thromboses and unsuccessful thrombectomies were noted during the COVID-19 pandemic. This difference could be due to a delay in patients getting procedures to maintain their dialysis accesses.

ASDIN white paper: Management of cephalic arch stenosis endorsed by the American Society of Diagnostic and Interventional Nephrology

Brachiocephalic arteriovenous fistulas (AVF) makeup approximately one third of prevalent dialysis vascular accesses. The most common cause of malfunction with this access is cephalic arch stenosis (CAS). The accepted requirement for treatment of a venous stenosis lesion is ⩾50% stenosis associated with hemodynamically abnormalities. However, the correlation between percentage stenosis and a clinically significant decrease in access blood flow (Qa) is low. The critical parameter is the absolute minimal luminal diameter (MLD) of the lesion. This is the parameter that exerts the key restrictive effect on Qa and results in hemodynamic and functional implications for the access. CAS is the result of low wall shear stress (WSS) resulting from the effects of increased blood flow and the unique anatomical configuration of the CAS. Decrease in WSS has a linear relationship to increased blood flow velocity and neointimal hyperplasia exhibits an inverse relationship with WSS. The result is a stenotic lesion. The presence of downstream venous stenosis causes an inflow-outflow mismatch resulting in increased pressure within the access. Qa in this situation may be decreased, increased, or within a normal range. Over time, the increased intraluminal pressure can result in marked aneurysmal changes within the AVF, difficulties with cannulation and the dialysis treatment, and ultimately, increasing risk of access thrombosis. Complete characterization of the lesion both hemodynamically and anatomically should be the first step in developing a strategy for management. This requires both access flow measurement and angiographic imaging. Patients with CAS present a relatively broad spectrum as relates to both of these parameters. These data should be used to determine whether primary treatment of CAS should be directed toward the anatomical lesion (small MLD and low Qa) or the pathophysiology (large MLD and high Qa).

Arteriovenous Access Type and Risk of Mortality, Hospitalization, and Sepsis Among Elderly Hemodialysis Patients: A Target Trial Emulation Approach

RATIONALE & OBJECTIVE

Evidence is mixed regarding the optimal choice of the first permanent vascular access for elderly patients receiving hemodialysis (HD). Lacking data from randomized controlled trials, we used a target trial emulation approach to compare arteriovenous fistula (AVF) versus arteriovenous graft (AVG) creation among elderly patients receiving HD.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

Elderly patients included in the US Renal Data System who initiated HD with a catheter and had an AVF or AVG created within 6 months of starting HD.

EXPOSURE

Creation of an AVF versus an AVG as the incident arteriovenous access.

OUTCOMES

All-cause mortality, all-cause and cause-specific hospitalization, and sepsis.

ANALYTICAL APPROACH

Target trial emulation approach, high-dimensional propensity score and inverse probability of treatment weighting, and instrumental variable analysis using the proclivity of the operating physician to create a fistula as the instrumental variable.

RESULTS

A total of 19,867 patients were included, with 80.1% receiving an AVF and 19.9% an AVG. In unweighted analysis, AVF creation was associated with significantly lower risks of mortality and hospitalization, especially within 6 months after vascular access creation. In inverse probability of treatment weighting analysis, AVF creation was associated with lower incidences of mortality and hospitalization within 6 months after creation (hazard ratios of 0.82 [95% CI, 0.75-0.91] and 0.82 [95% CI, 0.78-0.87] for mortality and all-cause hospitalization, respectively), but not between 6 months and 3 years after access creation. No association between AVF creation and mortality, sepsis, or all-cause, cardiovascular disease-related, or infection-related hospitalization was found in instrumental variable analyses. However, AVF creation was associated with a lower risk of access-related hospitalization not due to infection.

LIMITATIONS

Potential for unmeasured confounding, analyses limited to elderly patients, and absence of data on actual access use during follow-up.

CONCLUSIONS

Using observational data to emulate a target randomized controlled trial, the type of initial arteriovenous access created was not associated with the risks of mortality, sepsis, or all-cause, cardiovascular disease-related, or infection-related hospitalization among elderly patients who initiated HD with a catheter.

Mega Fistulae! A case series

A mega fistula can be defined as generalized aneurysmal dilatation of arteriovenous fistula. Mega fistulae can lead to complications like high output cardiac failure, steal syndrome, skin ulceration and rupture. We describe a series of ten patients who were referred to our interventional nephrology practice for evaluation of mega fistula which had not been in use for a long time. Nine out of ten patients were post-transplant while one was pre dialysis. Five patients had Radiocephalic while four had Brachiocephalic and one had Brachial artery to Median Cubital vein fistula. All except one patient had severe outflow stenosis. The most common site of stenosis in Radiocepahlic and Brachiocepahlic fistula was cephalic vein at the elbow and cephalic arch respectively. Half of the patients had chronic total occlusion of the outflow vein. Successful angioplasty was done in only two patients. Seven patients underwent ligation while one had spontaneous thrombosis of the fistula. None of the patients had regular surveillance of their access for a long time as they were not on dialysis. Unrecognized and uncorrected outflow stenosis over a long time period can lead to creation of mega fistula. Once a mega fistula develops there are not many treatment options other than ligation. This leads to loss of the access which might be needed in future. Continuous access surveillance in patients who are not on dialysis is important to prevent complications like mega fistula.

Perspectives in Individualizing Solutions for Dialysis Access

The vascular access is the lifeline for the hemodialysis patient. Previous national vascular access guidelines have emphasized placement of arteriovenous fistulas in most hemodialysis patients. However, the new Kidney Disease Outcomes Quality Initiative guidelines for vascular access, soon to be published, will focus on a patient's end-stage kidney disease "life plan" and take a patient "first" approach. One of the major themes of the new Kidney Disease Outcomes Quality Initiative guidelines is selecting the "right access, for the right patient, at the right time, for the right reason". Given the availability of new advances in biomedical technologies, techniques, and devices in the vascular access field, this shift to a more patient-centered vascular access approach presents unique opportunities to individualize the solutions and care for patients requiring a dialysis vascular access. This review article will address 3 potential areas where there is an unmet need to individualize solutions for dialysis vascular access care: (1) biological approaches to improve vascular access selection and selection of therapies, (2) vascular access care for the post-transplant patient, and (3) vascular access disparities in race, gender, and the elderly patient.

Teriparatide Treatment for Hypercalcemia Associated With Adynamic Bone Disease

Hypercalcemia most often results from primary hyperparathyroidism and malignancy. Adynamic bone disease (ABD) is a form of renal osteodystrophy characterized by reduced bone turnover, which can limit the ability of bone to release or store calcium, potentially leading to low, normal, or high serum calcium levels. We describe a 51‐year‐old dialysis‐dependent female with hypercalcemia after parathyroidectomy. A demeclocycline‐labeled bone biopsy confirmed adynamic bone disease. Teriparatide, a recombinant form of parathyroid hormone (PTH) used to treat postmenopausal osteoporosis, was prescribed for 12 months and normalized serum calcium levels. Although previous case reports and series have described favorable changes in spine bone mineral density when teriparatide was prescribed for ABD, ours is the first documented case in which teriparatide resolved hypercalcemia due to ABD. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Association of Pre-Transplant Dialysis Modality and Post-Transplant Outcomes: A Meta-Analysis

♦ BACKGROUND: It remains unclear whether post-transplant outcomes differ according to the pre-transplant dialysis modality (peritoneal dialysis [PD] versus hemodialysis [HD]). We performed a meta-analysis of studies that assessed either post-transplant mortality, graft survival, or delayed graft function (DGF) in both PD and HD patients. ♦ METHODS: Two independent authors searched English-language literature from January 1, 1980, through August 31, 2014, national conference proceedings, and reference lists. We used combinations of terms related to dialysis (hemodialysis, peritoneal dialysis, or renal replacement therapy), kidney transplant, and outcomes. Studies were included if they measured any of the 3 post-transplant study outcomes in both pre-transplant HD and PD. ♦ RESULTS: A total of 16 studies were included in the final analysis. Of these, 6 studies reported adjusted hazard ratio for mortality, pooled adjusted risk ratio: 0.89 (95% confidence interval [CI] 0.82 - 0.97) in favor of PD (p = 0.006). The same 6 studies reported adjusted hazard ratio for graft survival, pooled adjusted risk ratio: 0.97 (95% CI 0.92 - 1.01, p = 0.16). A total of 13 studies reported unadjusted DGF. Pooled odds ratio: 0.5 (95% CI 0.41 - 0.63) in favor of PD (p < 0.005). Significant heterogeneity observed for all outcomes: I2 = 72.7%, I2 = 59.9%, and I2 = 66.8%, respectively. ♦ CONCLUSIONS: Based on these results, pre-transplant PD is associated with better post-transplant survival than HD. Pre-transplant PD was also associated with decreased risk for DGF compared with HD, although these results were unadjusted. There was no significant difference in graft survival between pre-transplant HD and PD. These results suggest that PD may be the preferred dialysis modality for patients expected to receive a transplant.

Erosion of the Silicone Peritoneal Dialysis Catheter with the Use of Gentamicin Cream at the Exit Site

Infection remains the leading complication of peritoneal dialysis (PD). Topical mupirocin and gentamicin are frequently used to prevent infections. Mupirocin ointment has been reported to cause damage to both polyurethane and silicone PD catheters. Gentamicin cream has not been associated with physical damage to catheters.A 64-year-old woman on PD developed relapsing peritonitis with Staphylococcus epidermidis. Because of a drainage problem and white discoloration at the exit site, which is known as " frosting," she underwent catheter exchange. The catheter was found to be fractured within the area of frosting. Four more patients with frosting of the catheter were identified. On further questioning, it was recognized that they were applying excessive amounts of gentamicin cream directly on the catheter surface rather than at the exit site. All patients in the program were educated about the correct method of topical antibiotic application. After the change in practice, no further cases of catheter frosting were identified.Polyurethane catheters can undergo oxidation, mineralization, and environmental stress cracking, leading to physical damage such frosting, ballooning, and fracture. Polyethylene glycol, a component of the mupirocin ointment base, is thought to cause plasticization of polyurethane, reducing its tensile strength. Similar damage has been observed in silicone catheters. Previous reports have not found gentamicin cream to cause that type of damage. We observed that excessive amounts of cream applied directly to the catheter surface can damage it. Damage did not recur once patients had been educated about the proper method of application.

Hand Ischemia in a Patient With an Arteriovenous Fistula

An ischemic digit causes significant morbidity due to its associated discomfort and potential for tissue necrosis. Historically, when this phenomenon was peripheral to an ipsilateral arteriovenous access in a hemodialysis patient, it was called "steal syndrome" and was usually treated with access ligation, resulting in loss of the access. We present a dialysis patient with hand pain due to ischemia that was referred for access ligation. Instead, a minimally invasive banding procedure was performed that resulted in access salvage and resolution of symptoms. We present images and a discussion of the diagnosis and treatment of distal hypoperfusion ischemia syndrome in this Imaging Teaching Case.

A Multi-Center, Randomized, Controlled, Pivotal Study to Assess the Safety and Efficacy of a Selective Cytopheretic Device in Patients with Acute Kidney Injury

OBJECTIVE

Acute kidney injury (AKI) is a highly morbid condition in critically ill patients that is associated with high mortality. Previous clinical studies have demonstrated the safety and efficacy of the Selective Cytopheretic Device (SCD) in the treatment of AKI requiring continuous renal replacement therapy in the intensive care unit (ICU).

DESIGN, SETTING, PATIENTS

A randomized, controlled trial of 134 ICU patients with AKI, 69 received continuous renal replacement therapy (CRRT) alone and 65 received SCD therapy.

RESULTS

No significant difference in 60-day mortality was observed between the treated (27/69; 39%) and control patients (21/59; 36%, with six patients lost to follow up) in the intention to treat (ITT) analysis. Of the 19 SCD subjects (CRRT+SCD) and 31 control subjects (CRRT alone) who maintained a post-filter ionized calcium (iCa) level in the protocol's recommended range (≤ 0.4 mmol/L) for greater or equal to 90% of the therapy time, 60-day mortality was 16% (3/19) in the SCD group compared to 41% (11/27) in the CRRT alone group (p = 0.11). Dialysis dependency showed a borderline statistically significant difference between the SCD treated versus control CRRT alone patients maintained for ≥ 90% of the treatment in the protocol's recommended (r) iCa target range of ≤ 0.4 mmol/L with values of, 0% (0/16) and 25% (4/16), respectively (P = 0.10). When the riCa treated and control subgroups were compared for a composite index of 60 day mortality and dialysis dependency, the percentage of SCD treated subjects was 16% versus 58% in the control subjects (p<0.01). The incidence of serious adverse events did not differ between the treated (45/69; 65%) and control groups (40/65; 63%; p = 0·86).

CONCLUSION

SCD therapy may improve mortality and reduce dialysis dependency in a tightly controlled regional hypocalcaemic environment in the perfusion circuit.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01400893 http://clinicaltrials.gov/ct2/show/NCT01400893.

Initial vascular access type in patients with a failed renal transplant

BACKGROUND AND OBJECTIVES

Permanent hemodialysis vascular access is crucial for RRT in ESRD patients and patients with failed renal transplants, because central venous catheters are associated with greater risk of infection and mortality than arteriovenous fistulae or arteriovenous grafts. The objective of this study was to determine the types of vascular access used by patients initiating hemodialysis after a failed renal transplant.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Data from the US Renal Data System database on 16,728 patients with a failed renal transplant and 509,643 patients with native kidney failure who initiated dialysis between January 1, 2006, and September 30, 2011 were examined.

RESULTS

At initiation of dialysis, of patients with a failed transplant, 27.7% (n=4636) used an arteriovenous fistula, 6.9% (n=1146) used an arteriovenous graft, and 65.4% (n=10,946) used a central venous catheter. Conversely, 80.8% (n=411,997) of patients with native kidney failure initiated dialysis with a central venous catheter (P<0.001). Among patients with a failed transplant, predictors of central venous catheter use included women (adjusted odds ratio, 1.75; 95% confidence interval, 1.63 to 1.87), lack of referral to a nephrologist (odds ratio, 2.00; 95% confidence interval, 1.72 to 2.33), diabetes (odds ratio, 1.14; 95% confidence interval, 1.06 to 1.22), peripheral vascular disease (odds ratio, 1.31; 95% confidence interval, 1.16 to 1.48), and being institutionalized (odds ratio, 1.53; 95% confidence interval, 1.23 to 1.89). Factors associated with lower odds of central venous catheter use included older age (odds ratio, 0.85 per 10 years; 95% confidence interval, 0.83 to 0.87), public insurance (odds ratio, 0.74; 95% confidence interval, 0.68 to 0.80), and current employment (odds ratio, 0.87; 95% confidence interval, 0.80 to 0.95).

CONCLUSIONS

Central venous catheters are used in nearly two thirds of failed renal transplant patients. These patients are usually followed closely by transplant physicians before developing ESRD after a failed transplant, but the relatively low prevalence of arteriovenous fistulae/arteriovenous grafts in this group at initiation of dialysis needs to be investigated more thoroughly.

A case series of real-time hemodynamic assessment of high output heart failure as a complication of arteriovenous access in dialysis patients

Congestive heart failure (CHF) is an important source of morbidity and mortality in end-stage renal disease patients. Although CHF is commonly associated with low cardiac output (CO), it may also occur in high CO states. Multiple conditions are associated with increased CO including congenital or acquired arteriovenous fistulae or arteriovenous grafts. Increased CO resulting from permanent AV access in dialysis patients has been shown to induce structural and functional cardiac changes, including the development of eccentric left ventricle hypertrophy. Often, the diagnosis of high output heart failure requires invasive right heart monitoring in the acute care setting such as a medical or cardiac intensive care unit. The diagnosis of an arteriovenous access causing high output heart failure is usually confirmed after the access is ligated surgically. We present for the first time, a case for real-time hemodynamic assessment of high output heart failure due to AV access by interventional nephrology in the cardiac catheterization suite.

Pilot Study of the Effect of Lanthanum Carbonate (Fosrenol®) In Patients with Calciphylaxis: A Wisconsin Network for Health Research (WiNHR) Study

Background

Currently there is a lack of effective treatment options for patients with calciphylaxis. There is anecdotal evidence that non-calcium based phosphorus binders may offer some benefit. The aim of this pilot study is to determine if lanthanum carbonate is effective in inducing remission of calciphylaxis lesions and demonstrate an improved DLQI (Dermatology Life Quality Index).

Methods

This is a multi-site exploratory pilot study conducted through the Wisconsin Network for Health Research (WiNHR), a collaboration of health services researchers across the state of Wisconsin. Dialysis patients were recruited from in-center dialysis units, clinics and hospital admissions over a period of 24-months.

Results

Due to the low inclusion rate, the trial was terminated after which 4 patients were prospectively analyzed. Dose of lanthanum carbonate was escalated to 3750 mg divided into 3 meals and titrated according to level of serum phosphorus. Gastrointestinal symptoms were the most common adverse effect. All 4 patients achieved complete remission by definition of skin re-epithelialization. Secondary outcome measurements showed a significant improvement in serum albumin (B coeff 0.17, 95% CI 0.002-0.031; p=0.023) and a significant improvement in overall DLQI score (B coeff -0.46, 95% CI -0.85- -0.08; p=0.019).

Conclusions

Lanthanum carbonate appears to be efficacious as an adjunctive therapy to improve calciphylaxis lesions and symptom burden. More prospective clinical trials are warranted to determine the feasibility of this novel treatment strategy.

Chronic total occlusion and successful drug-eluting stent placement in Takayasu arteritis-induced renal artery stenosis

Takayasu arteritis-induced renal artery stenosis (TARAS) is a condition rarely described in the literature. Although percutaneous transluminal angioplasty and stenting has been well-described in the treatment of atherosclerotic renal artery stenosis, its role has not been established in non-atherosclerotic TARAS. We report a case of a female, age 17 years, with Takayasu arteritis who presented to the hospital with seizures and hypertensive crisis. A renal angiogram showed chronic total occlusion (CTO) of the left renal artery. Renal angioplasty and stenting was successfully performed after multiple attempts to deliver a wire distal to the CTO. After sequential balloon predilation, a drug-eluting stent was deployed, resulting in full reperfusion of the kidney. The patient's blood pressure improved dramatically, and patency of the stent was demonstrated with magnetic resonance angiography over 9 months after the procedure.

The effect of buttonhole cannulation vs. rope-ladder technique on hemodialysis access patency

The rope-ladder (RL) technique is the most common technique used for cannulation of arteriovenous fistulae (AVF). Buttonhole cannulation (BHC), or constant-site technique, is recommended by the National Kidney Foundation's Kidney Disease Outcome Quality Initiative (NKF/KDOQI) vascular access guidelines. We compared outcomes of primary patency, episodes of bacteremia, access blood flow (Qa), and quality of life (QoL) scores between RL and BHC patients. Using a prospectively collected, vascular access database, a total of 45 prevalent dialysis patients using BHC were compared with 38 patients using the RL technique over a median of 12 months (inter-quartile range: 4-27 months). The two groups did not differ significantly in demographics except that diabetes was more common in those using BHC as compared to rope-ladder (69% vs. 34%; p = 0.002). Risk factors associated with lack of primary patency were age (hazards ratio [HR] = 1.02 per decade; 95% CI: 1.00-1.03; p = 0.04) and female gender (HR = 1.92; 95% CI: 1.08-3.40; p = 0.03). Use of the buttonhole technique was not associated with improved primary patency (HR = 1.22, 95% CI: 0.65-2.28; p = 0.53). Episodes of bacteremia and mean scores from KDQOL-36 did not differ significantly between the groups. This study demonstrates for the first time that BHC use is not associated with improved access patency.

A case report of deferasirox-induced kidney injury and Fanconi syndrome

Cases of kidney injury associated with the use of deferasirox chelation therapy during the course of treatment for iron overload have been reported infrequently. We present the case of a patient treated with deferasirox who had biopsy-proven tubular injury in the setting of clinical Fanconi syndrome. The patient required hospitalization for metabolic acidosis, electrolyte abnormalities, and associated symptoms. With supportive care and cessation of chelation therapy he improved, but has yet to fully recover. This is the first known case reporting biopsy-proven tubular damage in the setting of deferasirox use.

The rationale, implementation, and effect of the Medicare CKD education benefit

Although it affects <1% of the US population, stage 4 chronic kidney disease (CKD) has increased in prevalence in the United States, grown 67% between the early 1990s and the first part of this decade. It is important to consider new strategies to slow or halt this increase. A frameshift in patient care delivery is underway in kidney health care in the United States with a Medicare education benefit for patients with stage 4 CKD. This Medicare benefit is a unique program that has the potential to inform patients and families about CKD and prepare them for transitions in health states and kidney health care. For the greatest value of this benefit to be realized, it is critical for the health care community to accurately gauge patient understanding of CKD and provide curricula that are comprehensible and actionable for patients. This type of benefit is patient centered, yet it will succeed only with a willingness to review its effectiveness and revise it if needed.

"Venopathy" at work: recasting neointimal hyperplasia in a new light

Hemodialysis vascular access is a unique form of vascular anastomosis. Although it is created in a unique disease state, it has much to offer in terms of insights into venous endothelial and anastomotic biology. The development of neointimal hyperplasia (NH) has been identified as a pathologic entity, decreasing the lifespan and effectiveness of hemodialysis vascular access. Subtle hints and new data suggest a contrary idea-that NH, to some extent an expected response, if controlled properly, may play a beneficial role in the promotion of maturation to a functional access. This review attempts to recast our understanding of NH and redefine research goals for an evolving discipline that focuses on a life-sustaining connection between an artery and vein.

Retrograde occlusive arteriography of hemodialysis access: failure to detect inflow lesions?

Once thought to be a minor player in hemodialysis (HD) access dysfunction relative to outflow stenosis, inflow stenosis has recently come to be viewed as a major cause of access failure. Indeed, recent literature has shown that up to 40% of all accesses referred for dysfunction have an inflow lesion. Imaging of the inflow segment has been traditionally performed by interventional nephrologists via retrograde occlusive arteriography (ROA). Recent advances in our understanding of ROA have cast the technique in a negative light, with the possibility of vascular complications and poor diagnostic yield coming to the fore. Using a prospectively collected, vascular access database, we identified 18 consecutive patients who received imaging of inflow lesions by ROA and direct arteriogram (DA). The mean percent luminal stenoses were found to be 59.89 ± 24 and 79.06 ± 17.8 (p = 0.009) for the ROA vs. DA groups, respectively. Using multiple regression analysis, DA was found to be associated with detecting higher degree of luminal stenosis (β = 19.17, 95% CI 6.28-32.05, p = 0.006). This small case series provides evidence on the theoretical concern that ROA does not adequately evaluate inflow lesions. We may conclude that by relying solely on ROA, interventional nephrologists may be failing to detect a subset of hemodynamically significant inflow lesions.

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.

Stent migration and folding in the subclavian vein during subclavian hemodialysis catheter placement

The role of stent placement in hemodialysis (HD) access intervention continues to evolve. As more stents are placed, new and unusual complications are coming to light. We describe a case in which an unsuccessful attempt to place a left subclavian dialysis catheter resulted in the inadvertent migration and folding of a previously deployed subclavian stent. Attempts to remove the stent with a snare were unsuccessful. Patency was restored to the access circuit by placing a new stent through the struts of the folded one. Clinical vascular practice guidelines for vascular access on the use of fluoroscopy for temporary HD catheter placement may need to be re-evaluated with the reported increase in stent placement in the US HD population.

Calciphylaxis responsive to lanthanum carbonate (FOSRENOL) therapy

Calciphylaxis is a rare and debilitating vasculopathy predominantly seen in patients with renal failure. The proposed mechanism of injury is active vascular calcification with associated elevated parathyroid hormone, hypercalcemia, or hyperphosphatemia. With improved pharmacologic agents including non-calcium containing phosphate binders, vitamin D analogues, calcimimetics, and bisphosphonates, targeted therapy on the mineralization process has been tried with varied success. We report a case of biopsy-proven calciphylaxis in a patient with acute kidney injury requiring dialysis that had persistently elevated calcium-phosphorus product refractory to treatment. The patient, however, responded rapidly to the initiation of lanthanum carbonate therapy and modified dialysis. This is the first known case reported in the literature utilizing this new non-calcium-based phosphate binder in the setting of calciphylaxis.

Recurrent atypical hemolytic uremic syndrome associated with factor I mutation in a living related renal transplant recipient

Atypical hemolytic uremic syndrome, or the nondiarrheal form of hemolytic uremic syndrome, is a rare disorder typically classified as familial or sporadic. Recent literature has suggested that approximately 50% of patients have mutations in factor H (CFH), factor I (CFI), or membrane cofactor protein (encoded by CD46). Importantly, results of renal transplantation in patients with mutations in either CFH or CFI are dismal, with recurrent disease leading to graft loss in the majority of cases. We describe an adult renal transplant recipient who developed recurrent hemolytic uremic syndrome 1 month after transplantation. Bidirectional sequencing of CFH, CFI, and CD46 confirmed that the patient was heterozygous for a novel missense mutation, a substitution of a serine reside for a tyrosine residue at amino acid 369, in CFI. This report reemphasizes the importance of screening patients with atypical hemolytic uremic syndrome for mutations in these genes before renal transplantation and shows the challenges in the management of these patients.

How I do it: endovascular stent deployment using a novel technique that obviates the need for introducer-sheath upsizing

A case is presented and a novel technique is described by which an endovascular stent is deployed in the venous outflow system of an arteriovenous fistula without the traditional exchange to a larger diameter introducer sheath.

Obesity as a predictor of vascular access outcomes: analysis of the USRDS DMMS Wave II study

Arteriovenous fistulae (AVF) are widely regarded as the preferred vascular access in hemodialysis patients due to their primary patency and patient survival benefits. While the obesity paradox has been associated with improved cardiovascular morbidity and all-cause mortality in dialysis patients, its long-term vascular access outcomes are less clear. Recent literature has suggested that obese patients may have increased early and late fistula failure. The purpose of this study was to explore the relationships between obesity and vascular access outcomes. We performed a retrospective cohort analysis using the USRDS DMMS Wave 2 data set. All incident dialysis patients as of January 1, 1996, over the age of 18, receiving only hemodialysis as mode of renal replacement therapy were eligible for inclusion. Among other variables, data collected for the DMMS Wave 2 included: type and location of vascular access, AVF maturity, vascular access revision, and failure. Logistic regression analyses were used to examine the relationships between obesity and vascular access outcomes, adjusting for important covariates. In all, 1486 hemodialysis patients were included. Using body mass index (BMI) <30 kg/m(2) as reference, obesity did not emerge as a factor in predicting vascular access revisions or failures. An increased risk of AVF failure to mature was found only in the highest BMI quartile (>or=35 kg/m(2)) (aOR 3.66 [95% CI 1.27-10.55], p = 0.017). Peripheral vascular disease was independently associated with an increased risk of AVF failure (aOR 2.78 [95% CI 1.01-7.63], p = 0.047) and arteriovenous graft (AVG) failure (aOR 1.65 [95% CI 1.03-2.64], p = 0.036). Obesity was not associated with increased AVF or AVG revision rates or failure and only associated with poorer AVF maturity at highest BMI quartile. We conclude that obesity should not preclude placement of AVF as vascular access of choice, except in the very obese where assessment should be individually based.

Stent placement versus angioplasty improves patency of arteriovenous grafts and blood flow of arteriovenous fistulae

BACKGROUND

While endovascular stent placement is the standard of care in most percutaneous coronary and peripheral artery intervention, its role in the salvage of thrombosed and stenotic hemodialysis access remains controversial.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

We compared the effects of stent versus angioplasty on primary patency rates in the treatment of stenotic arteriovenous fistulae (AVF) and arteriovenous grafts (AVGs). Moreover, we compared access flow (Qa) and urea reduction ratio (URR) between the two groups as a metric of the effect of stent placement versus angioplasty on dialysis delivery.

RESULTS

Cox regression analysis revealed that the primary assisted AVG patency was significantly longer for the stent group compared with angioplasty, with a median survival of 138 versus 61 d, respectively (aHR = 0.17; 95% confidence interval, 0.07 to 0.39; P < 0.001). The primary AVG patency for stent versus angioplasty was 91% versus 80% at 30 d, 69% versus 24% at 90 d, and 25% versus 3% at 180 d, respectively. The primary assisted AVF patency did not differ significantly between the stent and angioplasty groups. In patients dialyzing via AVF, multiple regression analysis revealed that stent placement was associated with improved after intervention peak Qa, 1627.50 ml/min versus 911.00 ml/min (beta = 0.494; P = 0.008), change in Qa from before to after intervention, 643.54 ml/min versus 195.35 ml/min (beta = 0.464; P = 0.012), and change in URR from before to after intervention, 5.85% versus 0.733% (beta = 0.389; P = 0.039).

CONCLUSIONS

Our results suggest that stent placement is associated with improved AVG primary assisted patency and improved AVF blood flow, which may significantly impact on dialysis adequacy.

How I do it: directional atherectomy for in-stent restenosis of a PTFE arteriovenous graft

We describe the use of directional atherectomy (DA) to restore patency of a thrombosed polytetrafluoroethylene arteriovenous graft with an in-stent restenosis at the venous anastomosis. Technically, the procedure described is not an atherectomy per se, but rather the removal of fibrosis and intimal hyperplasia with sharp endoluminal dissection. Certainly, the operator must be cautious when performing DA directly adjacent to a previously deployed stent. Nevertheless, our report suggests that there may be a role for DA in the treatment of severe, resistant in-stent stenosis. Further investigation is necessary to evaluate the safety and efficacy of the described technique.

Percutaneous, non-surgical placement of tunneled, cuffed, external jugular hemodialysis catheters: a case report

The right internal jugular vein is widely accepted as the vessel of choice for placement of long-term central venous catheters for hemodialysis. As vascular access sites become progressively depleted, alternate anatomic locations for access must be sought. We describe a non-surgical (fluoroscopy assisted, percutaneous) technique for placement of external jugular, tunneled, cuffed hemodialysis catheters, and provide long-term blood flow and dialysis adequacy data for EJV catheters.

Nephrogenic systemic fibrosis: risk factors and incidence estimation

PURPOSE

To retrospectively review data in 13 patients with biopsy-confirmed nephrogenic systemic fibrosis (NSF), assess the associated risk factors, and report the incidence of NSF at the authors' institution.

MATERIALS AND METHODS

This HIPAA-compliant study had institutional review board approval; informed consent was waived. Statistical analysis was performed for all available clinical and laboratory data in patients with biopsy-confirmed NSF. The data from the patients with NSF were compared with data from a control population of patients with renal insufficiency but who did not develop NSF.

RESULTS

There were eight male and five female patients, aged 17-69 years, with a diagnosis of NSF. Within 6 months of diagnosis, all 13 patients had been exposed to gadodiamide and one had been exposed to gadobenate dimeglumine in addition to gadodiamide. At the time of contrast material-enhanced magnetic resonance (MR) imaging, all 13 patients had renal insufficiency (estimated glomerular filtration rate [eGFR] < 60 mL/min/1.73 m(2)) and were hospitalized for a proinflammatory event (major surgery, infection, or vascular event). The group with NSF had significantly decreased eGFR (P = .01), more proinflammatory events (P < .001), and more contrast-enhanced MR examinations per patient (P = .002) than did the control group.

CONCLUSION

A combination of factors, including altered kidney function, inflammatory burden, and exposure to gadolinium-based contrast agents may all play a role in development of NSF. Alternative imaging should be considered in patients with these factors. If use of a gadolinium-based agent is clinically indicated, the referring physician and patient should be informed of the potential risk of developing NSF.