Arif Asif

Early Arteriovenous Fistula Failure: A Logical Proposal for When and How to Intervene

A significant number of arteriovenous fistulae (28 to 53%) never mature to support dialysis. Often, renal physicians and surgeons wait for up to 6 months and even longer hoping that the arteriovenous fistula (AVF) will eventually grow to support dialysis before declaring that the AVF has failed. In the interim, if dialysis is needed, then a tunneled catheter is inserted, exposing the patient to the morbidity and mortality associated with the use of this device. In general, a blood flow of 500 ml/min and a diameter of at least 4 mm are needed for an AVF to be adequate to support dialysis therapy. In most successful fistulae, these parameters are met within 4 to 6 wk. Most important, commonly encountered problems (stenosis and accessory veins) that result in early AVF failure can be diagnosed easily with skillful physical examination. Recent studies have indicated that a great majority of fistulae that have failed to mature adequately can be salvaged by percutaneous interventions and become available for dialysis. Early intervention regarding identification and salvage of a nonmaturing AVF is critical for several reasons. First, an AVF is the best available type of access regarding complications, costs, morbidity, and mortality. Second, this approach minimizes catheter use and its associated complications. Finally, access stenosis is a progressive process and eventually culminates in complete occlusion, leading to access thrombosis. In this context, the opportunity to salvage the AVF that fails early may be lost. This report reviews the process of AVF maturation and suggests a strategy for when and how to intervene to identify and salvage AVF with early failure.

Factors associated with poor outcomes in patients with lupus nephritis.

The objective of this study was to identify the factors associated with important clinical outcomes in a case-control study of 213 patients with lupus nephritis. Included were 47% Hispanics, 44% African Americans and 9% Caucasians with a mean age of 28 years. Fifty-four (25%) patients reached the primary composite outcome of doubling serum creatinine, end-stage renal disease or death during a mean follow-up of 37 months. Thirty-four percent African Americans, 20% Hispanics and 10% Caucasians reached the primary composite outcome (P < 0.05). Patients reaching the composite outcome had predominantly proliferative lupus nephritis (WHO classes: 30% III, 32% IV, 18% V and 5% II, P < 0.025) with higher activity index score (7 ± 6 versus 5 ± 5, P<0.05), chronicity index (CI) score (4 ± 3 versus 2 ± 2 unit, P<0.025), higher baseline mean arterial pressure (MAP) (111 ± 21 versus 102 ± 14 mmHg, P<0.025) and serum creatinine (1.9 ± 1.3 versus 1.3 ± 1.0 mg/dL, P<0.025), but lower baseline hematocrit (29 ± 6 versus 31 + 5%, P<0.025) and complement C3 (54 ± 26 versus 65 + 33 mg/dL, P<0.025) compared to controls. More patients reaching the composite outcome had nephrotic range proteinuria compared to controls (74% versus 56%, P<0.025). By multivariate analysis, CI (hazard ratio [95% CI] 1.18 [1.07-1.30] per point), MAP (HR 1.02 [1.00-1.03] per mmHg), and baseline serum creatinine (HR 1.26 [1.04-1.54] per mg/dL) were independently associated with the composite outcome. We concluded that hypertension and elevated serum creatinine at the time of the kidney biopsy as well as a high CI are associated with an increased the risk for chronic renal failure or death in patients with lupus nephritis.

Accuracy of Physical Examination in the Detection of Arteriovenous Fistula Stenosis

BACKGROUND AND OBJECTIVES Physical examination has been highlighted to detect vascular access stenosis; however, its accuracy in the identification of stenoses when compared with the gold standard (angiography) has not been validated in a systematic manner. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS A prospective study was conducted of 142 consecutive patients who were referred for an arteriovenous fistula dysfunction to examine the accuracy of physical examination in the detection of stenotic lesions when compared with angiography. The findings of a preprocedure physical examination and diagnosis were recorded and secured in a sealed envelope. Angiography from the feeding artery to the right atrium was then performed. The images were reviewed by an independent interventionalist who had expertise in endovascular dialysis access procedures and was blinded to the physical examination, and the diagnosis was rendered. Cohens kappa was used as a measurement of the level of agreement beyond chance between the diagnosis made by physical examination and angiography. RESULTS There was strong agreement between physical examination and angiography in the diagnosis of outflow (agreement 89.4%, kappa = 0.78) and inflow stenosis (agreement 79.6%, kappa = 0.55). The sensitivity and specificity for the outflow and inflow stenosis were 92 and 86% and 85 and 71%, respectively. There was strong agreement beyond chance regarding the diagnosis of coexisting inflow-outflow lesions between physical examination and angiography (agreement 79%, kappa = 0.54). CONCLUSIONS The findings of this study demonstrate that physical examination can accurately detect and localize stenoses in a great majority of arteriovenous fistulas.

Short-Term, High-Dose Pamidronate-Induced Acute Tubular Necrosis: The Postulated Mechanisms of Bisphosphonate Nephrotoxicity

A 76-year-old man had biopsy-proven acute tubular necrosis (ATN) after intravenous administration of 3 doses of 60 mg of pamidronate (Aredia) over a 2-week period. Pamidronate was given to treat hypercalcemia of unknown etiology. Other potential causes of acute renal failure were excluded with appropriate investigations. The patients preexisting renal impairment in the context of high-doses of pamidronate might have been a potentiating factor for nephrotoxicity. The ATN encountered in this patient resolved; however, short-term hemodialysis was needed. To the best of our knowledge, this is the first reported case of short-term, high-dose pamidronate-induced ATN in the absence of concomitant nephrotoxins. Although necrotic and apoptotic cell death after bisphosphonate administration has been seen in a variety of cells, the exact mechanism of nephrotoxicity is unknown. This report presents a case of pamidronate-induced ATN and discusses the potential mechanisms of bisphosphonate-induced nephrotoxicity.

Peritoneal Dialysis Underutilization: The Impact of an Interventional Nephrology Peritoneal Dialysis Access Program

Peritoneal dialysis (PD) is an underutilized form of renal replacement therapy. Recent data have emphasized that only 12% of end‐stage renal disease (ESRD) patients are initiated on this form of therapy in the United States. Patients requiring PD have most often been referred to general surgeons for catheter placement. This has incurred additional delays in starting treatment and loss of decision‐making control by the referring nephrologist. To address this issue, we developed and incorporated our own PD access placement program into the preexisting chronic kidney disease (CKD) education program. To date, 46 patients have undergone 71 procedures. These included 51 (72%) PD catheter insertions, 14 (20%) removals, and 6 (8%) repositioning procedures for poor drainage. PD catheter insertion was performed peritoneoscopically under local anesthesia and a Fogarty catheter was used to reposition a migrated catheter. All of the procedures were performed by nephrologists in a dedicated interventional nephrology (IN) laboratory. All six repositioning procedures failed to restore optimal drainage. Five of these patients had the catheter removed and a new catheter placed during the same procedure. Of these five patients, one had recurrence of poor drainage and opted for hemodialysis (HD). The sixth patient declined reinsertion and chose HD. Of the remaining seven removal procedures, three were due to fungal peritonitis, one due to bowel perforation, one due to severe depression, one due to transplant, and one catheter was removed at the request of the primary physician in a terminally ill patient. Eight of the 51 catheter insertions were during the initial admission of a catastrophic dialysis start. Two of these patients started acute PD and avoided catheter placement for HD. Thirty‐seven of 46 patients have a functional PD catheter with a follow‐up of 8.6 ± 0.8 (mean ± SE) months. During an 18‐month period our PD population has increased from 43 to 80 patients. We conclude that a dedicated PD access placement program coupled with a CKD education program can have a dramatic impact on patient choice and PD growth.

Does catheter insertion by nephrologists improve peritoneal dialysis utilization? A multicenter analysis.

In contrast to hemodialysis (HD), peritoneal dialysis (PD) remains an underutilized form of renal replacement therapy in the United States. Although a variety of factors have been deemed responsible, timely insertion of a PD catheter may also be a contributory factor. We conducted a multicenter analysis to examine whether the establishment of a program for PD catheter insertion by nephrologists has a positive impact on the growth in the number of patients using PD. Data for catheter insertion performed by nephrologists were collected from three centers. Any change in the prevalent PD population at each respective center was compared to the number of PD patients during the period having the traditional surgical approach. Nephrologists at the three centers used the peritoneoscopic technique and performed catheter insertion under local anesthesia. In center 1, the PD population remained stable at between 38 and 45 patients (approximately 16% of the total end‐stage renal disease [ESRD] population) from 1993 to 2001. Nephrologists initiated a program for PD catheter insertion in 2001. The number of PD patients has increased to 101 (32% of the ESRD population). In center 2, the PD population remained stable at between 70 and 78 patients (approximately 17%) between 1988 and 1990. Catheter insertion by interventional nephrologists began in 1991. The number of PD patients has increased to 125 (22%). In center 3, the PD population remained at 20–30 patients (approximately 18%) between 1988 and 1991. Catheter placement by nephrologists was initiated in 1991. The number of PD patients increased to 97 (27%). Catheter insertion by interventional nephrologists was suspended in 2001. The number of PD patients has gradually declined to 25 (6%). This study suggests that catheter insertion by the nephrologist can have a positive impact on the utilization of PD.

Developing a comprehensive diagnostic and interventional nephrology program at an academic center

Procedure-related delays in the treatment of patients with renal disease can be minimized and nephrology care can be delivered more efficiently by a nephrologist trained in nephrology-related procedures. Referrals to a radiologist for renal ultrasound and biopsy, to a surgeon for dialysis access placement, and to an interventional radiologist for dialysis catheter placement and vascular access procedures are time consuming and inconvenient to patients with renal disease. Moreover, such an approach may result in delays in the availability of critical diagnostic information and a break in the continuity of care. In an effort to optimize the care of nephrology patients, we developed a diagnostic and interventional nephrology (DIN) program that effectively deals with nephrology-related procedures in a timely manner. At present, some of the commonly performed nephrology-related procedures at our center include diagnostic ultrasonography, ultrasound-guided renal biopsy, peritoneal dialysis access procedures, permanent tunneled hemodialysis catheter placement, and endovascular procedures for arteriovenous dialysis access dysfunction. To date, we have performed 893 procedures during a period of 2 years. This article describes our approach and the tools required to develop a DIN program at an academic medical center.

Cephalic Arch Stenosis

The Kidney Dialysis Outcomes Quality Initiative guidelines and the Fistula First Initiative for vascular access have had a measurable impact on the incidence and prevalence of the type of access used to deliver hemodialysis in the United States. There has been a yearly increase in the placement of arteriovenous fistulas and an exponential increase in endovascular treatment of failing and immature fistulas. Undoubtedly, the predominant cause of fistula malfunction is stenosis within the access system. The stenotic lesions can occur anywhere within the access system from the arteries to the outflow and central veins. One of the relatively common sites for stenosis in patients with brachiocephalic fistulas is the cephalic arch region. While access stenoses at many other sites have been successfully treated with percutaneous balloon angioplasty, the results of this approach in the management of cephalic arch stenosis (CAS) have been rather disappointing. This has been in part due to multiple factors including the resistant nature of the stenosis, the development of early restenosis, as well as poor patency and high vein rupture rates. This article discusses the anatomy, postulated etiology and percutaneous interventions for the treatment of CAS. In addition, the report highlights surgical alternatives to the management of stenosis in this segment of the cephalic vein.

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.

Venous mapping using venography and the risk of radiocontrast-induced nephropathy.

Venous mapping using venography has been considered to be the gold standard for identifying veins suitable for arteriovenous fistula (AVF) creation. By utilizing a radiocontrast medium, however, venography introduces the risk of radiocontrast‐induced nephropathy. The risk of this complication in the chronic kidney disease (CKD) population has not been previously studied. Twenty‐five consecutive patients (CKD stage 4 and 5) undergoing venography were enrolled in this study. Patients were advised not to fast for the procedure and were encouraged to take oral fluids. Radiocontrast‐induced nephropathy was defined as a 20% decrease in the estimated glomerular filtration rate (GFR) from the baseline value at 48 hours after contrast administration. Weekly telephone calls were made for a total of 4 weeks to assess the need for dialysis. Venography was performed by interventional nephrology using 10–20 cc of low osmolarity contrast medium. Data were collected prospectively. Median age was 48.9 ± 7.8 years and 52% of the patients had diabetes. Complete sets of pre‐ and postprocedure GFRs were available in 21 patients. At 48 hours, there were no differences between the pre‐ and postprocedure GFRs. At the third week, one patient developed flu‐like symptoms with severe gastroenteritis and was hospitalized for volume depletion. This patient initiated dialysis during the hospital stay. We conclude that at 48 hours, our cohort did not develop radiocontrast‐induced nephropathy. During the 4‐week phone call follow‐up, only one patient needed dialysis. Large‐scale studies with a longer follow‐up using GFR estimation are needed to confirm these preliminary findings.