Artroplastía total de cadera en paciente con enfermedad de Paget: presentación de un caso / Total hip arthroplasty in a patient with Paget's disease. A case report

Introducción: La enfermedad de Paget es un trastorno metabólico de etiología desconocida, secundario a un incremento en la función de los osteoclastos y la consecuente respuesta de los osteoblastos a la formación exagerada de hueso. Compromete con mayor frecuencia el fémur proximal y, a menudo, se diagnostica incidentalmente. Se presenta el caso de una mujer con antecedente de enfermedad de Paget y pseudoartrosis de cadera izquierda, con indicaciones de prótesis total de cadera izquierda y un episodio único de luxación, sin complicaciones posteriores y una adecuada evolución. Conclusión: El manejo quirúrgico en casos de fractura de cadera permite restablecer la marcha y mejorar la calidad de vida de los pacientes con enfermedad de Paget. A pesar de ser una patología que dificulta el manejo de los pacientes, la enfermedad de Paget no es una contraindicación para la artroplastia total de cadera y permite mejorar el dolor y recuperar la funcionalidad. Nivel de Evidencia: IV

Introduction: Paget's disease is a metabolic disorder of unknown etiology, secondary to an increase in the function of osteoclasts and the consequent response of osteoblasts to excessive bone formation. It most commonly involves the proximal femur and is often diagnosed incidentally. We present the case of a woman with a history of Paget's disease and nonunion of the left hip, with indications for a total left hip prosthesis and a single episode of dislocation, without subsequent complications and an adequate evolution. Conclusion: Surgical management in cases of hip fracture allows to restore walking and improves the quality of life of patients with Paget's disease. Despite being a pathology that makes patient management difficult, Paget's disease is not a contraindication for total hip arthroplasty and allows the improvement of pain and restoration of functionality. Level of Evidence: IV

A Prospective, Randomized Study of an Expanded Polytetrafluoroethylene Stent Graft versus Balloon Angioplasty for In-Stent Restenosis in Arteriovenous Grafts and Fistulae: Two-Year Results of the RESCUE Study.

PURPOSE: To assess the safety and efficacy of an expanded polytetrafluoroethylene stent graft versus balloon angioplasty for the treatment of in-stent restenosis in the venous outflow of hemodialysis access grafts and fistulae. MATERIALS AND METHODS: Two hundred seventy-five patients were randomized at 23 US sites to stent-graft placement or percutaneous transluminal angioplasty (PTA). Primary study endpoints were access circuit primary patency (ACPP) at 6 months and safety through 30 days; secondary endpoints were evaluated through 24 months. RESULTS: ACPP at 6 months was significantly higher in the stent-graft group (18.6%) versus the PTA group (4.5%; P < .001), and freedom from safety events (30 days) was comparable (stent graft, 96.9%; PTA, 96.4%; P = .003 for noninferiority). The separation in ACPP survival curves remained through 12 months (stent graft, 6.2%; PTA, 1.5%). Treatment area primary patency (TAPP) was superior for the stent-graft group (66.4%) versus the PTA group (12.3%) at 6 months (P < .001), with a survivorship difference in favor of stent-graft placement maintained through 24 months (stent graft, 15.6%; PTA, 2.2%). ACPP and TAPP for the stent-graft group were better than those for the PTA group when compared within central and peripheral vein subgroups (P < .001). In central veins, TAPP was 13.6% in the stent-graft group versus 4.3% in the PTA group at 24 months (P < .001). CONCLUSIONS: Stent-graft use provided better ACPP and TAPP than PTA when treating in-stent restenosis in patients receiving dialysis with arteriovenous grafts and fistulae.

Understanding surgical preference and practice in hemodialysis vascular access creation.

Understanding healthcare providers' preferences, values, and beliefs around AVF eligibility is important to explain variability in practice. We conducted a survey of international surgeons, using hypothetical patient scenarios, to assess resources used, variables, perceived barriers, and absolute contraindications to access creation. A total of 134 surgeons completed the survey. Venous duplex ultrasound mapping (VDUM) was offered to all patients by 90% of US, 68% Canadian, and 63% European respondents. VDUM altered clinical decision less than 25% of the time for 33% American, 48% Canadian, and 85% European surgeons. Increased comorbidities and previous failed access were deterrents to AVF creation as was vessel size. Second choice access was the AV graft in the US and Europe and the catheter in Canada. Absolute contraindications to AVF creation included patient life expectancy <1 year, left ventricular ejection fraction (LVEF) <15%, and a history of dementia, while 42% surgeons reported no absolute contraindications. Perceived barriers included patient preferences, long wait times for surgery, and late referral to a Nephrologist. Significant variability exists in the surgical preoperative assessment of patients, and the eligibility criteria used for fistula creation. Understanding surgeons' preferences can aid in establishing standardization for VA access eligibility, including surgical assessment.

Minimizing hemodialysis catheter dysfunction: an ounce of prevention.

The maintenance of tunneled catheter (TC) patency is critical for the provision of adequate hemodialysis in patients who are TC-dependent. TC dysfunction results in the need for costly and inconvenient interventions, and reduced quality of life. Since the introduction of TCs in the late 1980s, heparin catheter lock has been the standard prophylactic regimen for the prevention of TC dysfunction. More recently, alternative catheter locking agents have emerged, and in some cases have shown to be superior to heparin lock with respect to improving TC patency and reducing TC-associated infections. These include citrate, tissue plasminogen activator, and a novel agent containing sodium citrate, methylene blue, methylparaben, and propylparaben. In addition, prophylaxis using oral anticoagulants/antiplatelet agents, including warfarin, aspirin, ticlodipine, as well as the use of modified heparin-coated catheters have also been studied for the prevention of TC dysfunction with variable results. The use of oral anticoagulants and/or antiplatelet agents as primary or secondary prevention of TC dysfunction must be weighed against their potential adverse effects, and should be individualized for each patient.

Academic interventional nephrology: a model for training, research, and patient care.

Dialysis vascular access dysfunction is currently a huge clinical problem. We believe that comprehensive academic-based dialysis vascular access programs that go all the way from basic and translational science investigation to clinical research to a dedicated curriculum and opportunities in vascular access for nephrologists in training are essential for improving dialysis vascular access care. This paper reviews the fundamental concepts and requirements for us to move toward this vision.

Association of factor V gene polymorphism with arteriovenous graft failure.

BACKGROUND: Dialysis grafts fail due to recurrent stenosis and thrombosis. Vasoactive and prothrombotic substances affecting intimal hyperplasia or thrombosis may modify graft outcomes. STUDY DESIGN: Genetic polymorphisms association study of patients enrolled in a multicenter randomized clinical trial. SETTING & PARTICIPANTS: 354 Dialysis Access Consortium (DAC) Study patients receiving a new graft with DNA samples obtained. Participants were randomly assigned to treatment with aspirin plus dipyridamole versus placebo. PREDICTOR: DNA sequence polymorphisms for the following candidate genes and their interaction with the study intervention: methylenetetrahydrofolate reductase (MTHFR), heme oxygenase 1 (HO-1), factor V (F5), transforming growth factor ß1 (TGFß1), klotho, nitric oxide synthase (NOS), and angiotensin-converting enzyme (ACE). OUTCOME: Graft failure (>50% stenosis, angioplasty, thrombosis, surgical intervention, or permanent loss of function). RESULTS: During a median patient follow-up of 34.3 months, 304 grafts failed. After adjusting for clinical factors (patient age, sex, access location, diabetes, cardiovascular disease, baseline aspirin use, body mass index, timing of graft placement, and study treatment) and genetic ancestral background, single-nucleotide polymorphism rs6019 of the factor V gene was associated significantly with graft failure in a dominant model (HR of 1.70 [95% CI, 1.32-2.19; P < 0.001] for G/C and G/G genotypes vs C/C genotypes). There was no significant association between graft failure and polymorphisms of MTHFR, HO-1, TGFß1, klotho, NOS, or ACE. LIMITATIONS: Small sample size. CONCLUSION: The rs6019 genotype of Factor V is associated with increased risk of graft failure. Anticoagulation may reduce graft failure in patients with the G/C or G/G genotypes.

Dialysis vascular access management by interventional nephrology programs at University Medical Centers in the United States.

The development of interventional nephrology has undoubtedly led to an improvement in patient care at many facilities across the United States. However, these services have traditionally been offered by interventional nephrologists in the private practice arena. While interventional nephrology was born in the private practice setting, several academic medical centers across the United States have now developed interventional nephrology programs. University Medical Centers (UMCs) that offer interventional nephrology face challenges, such as smaller dialysis populations, limited financial resources, and real or perceived political "turf" issues." Despite these hurdles, several UMCs have successfully established interventional nephrology as an intricate part of a larger nephrology program. This has largely been accomplished by consolidating available resources and collaborating with other specialties irrespective of the size of the dialysis population. The collaboration with other specialties also offers an opportunity to perform advanced procedures, such as application of excimer laser and endovascular ultrasound. As more UMCs establish interventional nephrology programs, opportunities for developing standardized training centers will improve, resulting in better quality and availability of nephrology-related procedures, and providing an impetus for research activities.

Standardized definitions for hemodialysis vascular access.

Vascular access dysfunction is one of the leading causes of morbidity and mortality among end-stage renal disease patients. Vascular access dysfunction exists in all three types of available accesses: arteriovenous fistulas, arteriovenous grafts, and tunneled catheters. To improve clinical research and outcomes in hemodialysis (HD) access dysfunction, the development of a multidisciplinary network of collaborative investigators with various areas of expertise, and common standards for terminology and classification in all vascular access types, is required. The North American Vascular Access Consortium (NAVAC) is a newly formed multidisciplinary and multicenter network of experts in the area of HD vascular access, who include nephrologists and interventional nephrologists from the United States and Canada with: (1) a primary clinical and research focus in HD vascular access dysfunction, (2) national and internationally recognized experts in vascular access, and (3) a history of productivity measured by peer-reviewed publications and funding among members of this consortium. The consortium's mission is to improve the quality and efficiency in vascular access research, and impact the research in the area of HD vascular access by conducting observational studies and randomized controlled trials. The purpose of the consortium's initial manuscript is to provide working and standard vascular access definitions relating to (1) epidemiology, (2) vascular access function, (3) vascular access patency, and (4) complications in vascular accesses relating to each of the vascular access types.

Arteriovenous graft placement in predialysis patients: a potential catheter-sparing strategy.

BACKGROUND: When predialysis patients are deemed unsuitable candidates for an arteriovenous fistula, current guidelines recommend waiting until just before or after initiation of dialysis therapy before placing a graft. This strategy may increase catheter use when these patients start dialysis therapy. We compared the outcomes of patients whose grafts were placed before and after dialysis therapy initiation. STUDY DESIGN: Retrospective analysis of a prospective computerized vascular access database. SETTING & PARTICIPANTS: Patients with chronic kidney disease receiving their first arteriovenous graft (n = 248) at a large medical center. PREDICTOR: Timing of graft placement (before or after initiation of dialysis therapy). OUTCOME & MEASUREMENTS: Primary graft failure, cumulative graft survival, catheter dependence, and catheter-related bacteremia. RESULTS: The first graft was placed predialysis in 62 patients and postdialysis in 186 patients. Primary graft failure was similar for pre- and postdialysis grafts (20% vs 24%; P = 0.5). Median cumulative graft survival was similar for pre- and postdialysis grafts (365 vs 414 days; HR, 1.22; 95% CI, 0.81-1.98; P = 0.3). Median duration of catheter dependence after graft placement in the postdialysis group was 48 days and was associated with 0.63 (95% CI, 0.48-0.79) episodes of catheter-related bacteremia per patient. LIMITATIONS: Retrospective analysis, single medical center. CONCLUSION: Grafts placed predialysis have primary failure rates and cumulative survival similar to those placed after starting dialysis therapy. However, postdialysis graft placement is associated with prolonged catheter dependence and frequent bacteremia. Predialysis graft placement may decrease catheter dependence and bacteremia in selected patients.

Clinical management of dialysis catheter-related bacteremia with concurrent exit-site infection.

Dialysis catheter-related bacteremia (CRB) can frequently be treated with systemic antibiotics, in conjunction with an antibiotic lock, in an attempt to salvage the catheter. It is unknown whether CRB associated with an exit-site infection can be treated with such an approach. We retrospectively queried a prospective, computerized vascular access database, and identified 1436 episodes of CRB, of which 64 cases had a concurrent exit site. The frequency of concurrent exit-site infection was 9.6% with Staphylococcus epidermidis, 6.1% with Staphylococcus aureus, and only 0.7% with Gram negative CRB (p < 0.001 for Staphylococcus vs. Gram negative rods). Five serious complications (four major sepses and one endocarditis) occurred in 24 patients with S. aureus infection, but none in 32 episodes of S. epidermidis infection (p = 0.01). Catheter survival was significantly shorter in patients with S. aureus infections. The median catheter survival (without infection or dysfunction) was 14 days with S. aureus vs. 30 days with S. epidermidis infection (p = 0.035). In conclusion, concurrent exit-site infection is seen most commonly in association with Staphylococcal CRB. When the infecting organism is S. epidermidis, attempted salvage with systemic antibiotics and an antibiotic lock is reasonable. However, prompt catheter removal is indicated when the pathogen is S. aureus.

Comparison of radiocephalic fistulas placed in the proximal forearm and in the wrist.

Non-maturation is a common problem in patients receiving an arteriovenous fistula. The first vascular access choice is a distal radiocephalic fistula (dRCF) at the wrist. Patients with a failed dRCF or with vessels unsuitable for dRCF, the recommendation is to place a brachiocephalic fistula in the upper arm. Proximal forearm radiocephalic fistulas (pRCF) are created infrequently, but may permit a second forearm fistula before proceeding to the upper arm. The goal of the present study was to compare the outcomes of them. We retrospectively analyzed a computerized access database to compare the outcomes of 19 RCF and 39 dRCF placed during a 6-month period. The baseline characteristics were similar, except those with a pRCF were more likely to have previous access and be male. Primary failure (non-maturation) was lower for pRCF than dRCF (32 vs. 59%, p = 0.05); and excluding secondary failures, cumulative fistula survival was similar (92 vs. 86% at 1 year and 74 vs. 76% at 2 years, p = 0.56). pRCF may be an attractive alternative to a brachiocephalic fistula in patients who cannot receive a dRCF. pRCF has a lower non-maturation rate than that of a dRCF, and a comparable cumulative survival once it is used successfully for dialysis.

Successful models of interventional nephrology at academic medical centers.

The foundation of endovascular procedures by nephrologists was laid in the private practice arena. Because of political issues such as training, credentialing, space and equipment expenses, and co-management concerns surrounding the performance of dialysis-access procedures, the majority of these programs provided care in an outpatient vascular access center. On the basis of the improvement of patient care demonstrated by these centers, several nephrology programs at academic medical centers have also embraced this approach. In addition to providing interventional care on an outpatient basis, academic medical centers have taken a step further to expand collaboration with other specialties with similar expertise (such as with interventional radiologists and cardiologists) to enhance patient care and research. The enthusiastic initiative, cooperative, and mutually collaborative efforts used by academic medical centers have resulted in the successful establishment of interventional nephrology programs. This article describes various models of interventional nephrology programs at academic medical centers across the United States.

Brachiocephalic vein stent fracture: case series and literature review.

Stent fractures are commonly seen in the arterial circulation and there is paucity of literature describing venous stent fractures particularly in the central venous circulation. In this case series, we describe three patients on hemodialysis who underwent right brachiocephalic vein (BCV) stent placement for severe stenosis in two patients and occlusion in one patient. Over the course of time, these patients clinically presented with arm swelling, pain, and difficulty in dialysis because of stenosis related to stent fracture and intimal hyperplasia. Two of these patients were successfully treated by restenting.

Who should be referred for a fistula? A survey of nephrologists.

BACKGROUND: There is marked variation in the use of the arteriovenous fistula (AVF) across programmes, regions and countries not explained by differences in patient demographics or comorbidities. The lack of clear criteria of who should or should not get a fistula may contribute to this, as well as barriers to creating AVFs. METHODS: We conducted a survey of Canadian and American nephrologists to assess the patient variables considered to determine the timing and type of access requested. Perceived barriers and absolute contraindications to access were also collected. RESULTS: An immediate referral for a fistula was more highly preferred when patients are <65 years old, have minimal comorbidities or have no history of failed accesses. In older patients, and in those with increased comorbidities or a previously failed fistula, US nephrologists selected arteriovenous grafts as an alternative to the fistula, while Canadian nephrologists selected primarily catheters. Referral for vascular mapping was more common in the USA than in Canada. Gender did not influence the timing or the type of access. Perceived barriers to establishing a mature fistula included patient refusal for creation (77%) or cannulation (58%), delay in decision regarding dialysis modality (71%), wait time for surgical creation (55%) and high failure-to-mature rate (52%). We found that 27% of Canadian and 43% of American nephrologists indicated no absolute contraindications for permanent vascular access. CONCLUSIONS: This study demonstrated marked variability in timing and criteria used to select patients for referral for a vascular access between nephrologists practicing within Canada and the USA. Establishing minimal eligibility criteria for fistulae is an important area of future research.

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.

Does heparin coating improve patency or reduce infection of tunneled dialysis catheters?

BACKGROUND AND OBJECTIVES: Tunneled dialysis catheters are prone to frequent malfunction and infection. Catheter thrombosis occurs despite prophylactic anticoagulant locks. Catheter thrombi may also serve as a nidus for catheter infection, thereby increasing the risk of bacteremia. Thus, heparin coating of catheters may reduce thrombosis and infection. This study evaluated whether heparin-coated hemodialysis catheters have fewer infections or greater cumulative survival than noncoated catheters. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We retrospectively queried a prospective access database to analyze the outcomes of 175 tunneled dialysis catheters placed in the internal jugular vein, including 89 heparin-coated catheters and 86 noncoated catheters. The primary outcome was cumulative catheter survival, and the secondary outcome was infection-free catheter survival. RESULTS: The two patient groups were similar in demographics and clinical and catheter features. Catheter-related bacteremia occurred less frequently with heparin-coated catheters than with noncoated catheters (34 versus 60%, P < 0.001). Cumulative catheter survival was similar in heparin-coated and noncoated catheters (hazard ratio, 0.87; 95% confidence interval, 0.55 to 1.36; P = 0.53). On multiple variable survival analysis including catheter type, age, sex, diabetes, coronary artery disease, peripheral vascular disease, cerebrovascular disease, catheter location, and previous catheter, only catheter location predicted cumulative catheter survival (hazard ratio, 2.03; 95% CI, 1.27 to 3.25, with the right internal jugular location being the reference group, P = 0.003). The frequency of thrombolytic instillation was 1.8 per 1000 catheter-days in both groups. CONCLUSIONS: Heparin coating decreases the frequency of catheter-related bacteremia but does not reduce the frequency of catheter malfunction.

Endovascular stents for dialysis access: under what circumstances do the data support their use?

Despite strict K/DOQI clinical practice guidelines regarding the deployment of stents in the hemodialysis vascular circuit, their use has increased exponentially over the last 10 years in both arteriovenous fistulas and grafts. The literature is very scant regarding outcomes, with most studies suffering from design flaws. Some authors have advocated the use of stents for specific clinical scenarios, such as patients with thrombosed arteriovenous grafts or ones with a severe stenosis at the venous anastomosis. Others have advocated a more liberal strategy to deploy stents at a variety of sites if the stenotic lesion remains greater than 30% after angioplasty. Although not approved for the treatment of pseudoaneurysms in the AV grafts, stent use in this setting is emerging to be an important strategy. The use of stents as a treatment for rupture of a vessel while performing a percutaneous angioplasty is well described and performed routinely. It is important to recognize the clinical scenarios when stent placement may present a distinct disadvantage (eg, loss of a potential secondary fistula creation in the same extremity). Finally, well-designed studies need to address all these issues to clarify indications and to provide stronger scientific guidelines for stent use.

Current concepts in the pathophysiology and management of arteriovenous access-induced hand ischemia.

The manifestations of hand ischemia because of an arteriovenous access can range from hand pain, tissue necrosis, and loss of the entire hand. Recent data have emphasized that multiple mechanisms (arterial steal, ie, retrograde flow, arterial stenosis, and arterial calcification) are responsible for inducing hand ischemia. Because any or a combination of the 3 mechanisms can lead to peripheral ischemia, distal hypoperfusion ischemic syndrome is a more appropriate term to denote hand ischemia. A detailed history, physical examination, and differential diagnosis form the initial step in the management of distal hypoperfusion ischemic syndrome. A complete arteriogram to evaluate the circulation of the extremity from the aortic arch to the palmar arch is essential. The choice of treatment modality should be based on this evaluation. In this article, we review the pathophysiology and present current strategies to ameliorate distal hypoperfusion ischemic syndrome.

Percutaneous renal biopsy: outpatient observation without hospitalization is safe.

Percutaneous renal biopsy may be complicated by hemorrhage. Patients are frequently hospitalized for overnight observation. We evaluated prospectively the feasibility and safety of an outpatient renal biopsy protocol. During a 20-month period, 100 consecutive patients underwent outpatient renal biopsy using a standardized protocol. The biopsy was performed by Nephrology Fellows, under direct faculty supervision. All biopsies were carried out under real-time ultrasound guidance with a 16-gauge spring-loaded biopsy gun, and followed immediately by color Doppler ultrasound to exclude active bleeding. Blood pressure, heart rate, hemoglobin, and hematocrit were monitored for 8 hours postbiopsy. If there were no complications, the patients were discharged home after the observation period. A total of 91 patients required one or two needle passes, and nine needed three or four passes. A mean of 12.7 +/- 9.7 glomeruli were obtained per patient. No major complications were encountered. A small (<2 x 2 cm) perinephric hematoma was observed postbiopsy in 13 patients. Four patients were hospitalized for overnight observation due to a >4% decrease in their hematocrit, but none required a transfusion or intervention. No patient experienced a delayed biopsy-related complication. Outpatient, real-time, ultrasound-guided percutaneous renal biopsy is safe and effective, and minimizes the need for postbiopsy hospitalization. It can result in significant cost savings without exposing the patients to an increased risk of complications.