Catheter thrombosis.

Catheter malfunction due to poor flow is a common problem. When it occurs early, the cause is generally technical. Late occurrences are most often related to thrombus formation. Several types of thrombus may be seen, differing by location and supposed mechanism of formation. The most common offender, however, is the fibrin sheath thrombus. Prevention of catheter malfunction is an endeavor that continues to beg many questions. Catheter malfunction should be treated early to avoid inadequate dialysis. In the past, urokinase was a highly valuable aid to the nephrologist in managing this problem. Since this agent became unavailable a suitable alternative has not emerged. Recombinant tissue plasminogen activator (tPA) seems to be the most likely candidate for this role; however, it is not currently available in a packaging form that is optimal for this purpose. Currently, catheter exchange appears to be the best available alternative for this problem, which cannot yet be resolved by simpler means.

Initial clinical results with the LifeSite Hemodialysis Access System.

BACKGROUND: The LifeSite Hemodialysis Access System is a subcutaneous valve with an internal pinch clamp that is actuated with a standard 14-gauge dialysis needle, connected to a single lumen cannula placed in the central venous circulation for hemodialysis (HD). METHODS: The LifeSite System (2 valves) was implanted in 23 patients with immediate dual-needle HD use. The cannulas were placed in either the jugular or the subclavian veins and were connected to the subcutaneous valves located in the upper chest area. RESULTS: The mean duration of device survival for the LifeSite System was 6.8 +/- 0.97 months. During this period, the device achieved prescription HD blood flow rates averaging 384.7 +/- 78.5 mL/min with a venous pressure of 223.2 +/- 60.3 mm Hg. After 125 patient months, device removal because of infection was at a rate of 2.5 per 1000 days, and there were no devices removed because of poor flow. The average Kt/V for these patients was 1.51. CONCLUSION: This preliminary clinical study has validated the applicability of the LifeSite Hemodialysis Access System as an access for HD. It is easily implanted and easily used, provides safe and effective dialysis, and is well accepted by patients. It should be especially useful as a bridge device to allow for maturation of a native fistula and will provide an alternative for long-term use in patients in whom a peripheral dialysis access is not feasible.

Strategy for maximizing the use of arteriovenous fistulae.

Increasing the use of arteriovenous fistulae in dialysis patients requires a specific strategy. In order to properly select patients for an arteriovenous fistula (AVF), it is essential that the nephrologist become knowledgeable about the subject and that an organized approach be followed. Both the arterial and venous systems must be evaluated. Evaluation of medical history, general physical examination, specific physical examination related to the vasculature of the extremity, vein mapping and duplex ultrasound studies are all important. It is very important to assess the size of the vessels involved. Although a newly created AVF should be allowed to fully mature prior to use, failure to develop should be evaluated early. Many cases of early failure can be successfully salvaged. Even if the patient has an arteriovenous graft, they should be evaluated at the time of every graft failure for the possibilities of creating a secondary AVF.

The hemodialysis catheter conundrum: hate living with them, but can't live without them.

BACKGROUND: Hemodialysis requires reliable recurrent access to the circulation. On a chronic basis, this has been best provided by the use of arteriovenous fistulae and arteriovenous grafts. In recent years, hemodialysis catheters have come to play an increasingly important role in the delivery of hemodialysis. The use of both temporary as well as cuffed hemodialysis catheters has emerged as a significant boon for both patients and practicing nephrologists. The complications, however, associated with each of these hemodialysis catheters, both in terms of anatomic, thrombotic, and infectious issues, have emerged as a major problem with their continued use. This significant morbidity and complication rate has forced many nephrologists to face a basic conundrum: they have come to hate having to deal with the problems inherent in catheter usage, but the enormous utility of these devices have forced physicians to accept the fact they cannot live without them in their current practice. METHODS: We used a comprehensive literature review to describe the types, use and dilemmas of hemodialysis catheters. RESULTS: This article provides a comprehensive review of both the benefits inherent with the use of these hemodialysis catheters while cataloging their complications and offering some possible solutions. CONCLUSION: Hemodialysis vascular access catheters are essential in the maintenance of hemodialysis vascular access. However, they have a significant infectious, thrombotic, anatomic complication rate that are detailed with proposed problem-solving guidelines.

Management of bacteremia associated with tunneled-cuffed hemodialysis catheters.

The dominant problem associated with the use of tunneled-cuffed catheters is infection. When this occurs, two issues must be addressed: treatment of the infection and management of the catheter. The purpose of this 2-yr study was to report the results of a prospective observational series in which catheter management was based on the clinical picture presented by the patient. Data were collected on patients with catheter-related bacteremia (CRB) dealt with in one of three ways: (1) minimal symptoms with a normal-appearing tunnel and exit site (exchange over guidewire within 48 h of antibiotic initiation [Xchng group], 49 cases); (2) minimal symptoms but with tunnel or exit site infection (exchange over a guidewire with creation of a new tunnel [Nutunl group], 28 cases); and (3) severe clinical symptoms (catheter removal with delayed replacement after defervescence [Delay group], 37 cases). All cases were treated immediately with empiric antibiotics followed by 3 wk of antibiotic therapy based on culture sensitivities. A cure was defined as a 45-d symptom-free interval after antibiotic therapy was complete. A cure rate total of 87.8% for the Xchng group, 75% for the Nutunl group, and 86.5% for the Delay group was seen for the 114 episodes of CRB. It is concluded that in selected patients, catheter exchange over a guidewire within 48 h of antibiotic initiation followed by 3 wk of specific antibiotic therapy is a viable treatment option. Additionally, replacing the catheter in patients presenting with severe symptoms of sepsis as soon as they have defervesced is a reasonable approach to therapy.

Salvage of the nonfunctioning arteriovenous fistula.

Two factors are necessary for an arteriovenous fistula (AVF) to be usable as dialysis access. It must have adequate blood flow, and it must have a size that will allow for cannulation. An AVF can remain patent in the face of relatively low blood flow. For effective dialysis, the AVF only has to deliver a blood flow that is marginally greater than the pump rate. Unfortunately, dialysis may not be technically possible in these cases with lower flow because the AVF does not mature sufficiently to a size adequate for cannulation. In this prospective observational series of 63 patients, failure of AVF development was the result of venous stenosis and/or the presence of accessory veins (venous side branches). The presence of these anomalies could be diagnosed by physical examination. After documentation by angiography, the patients were treated with angioplasty, venous ligation, or a combination of both. Three levels of venous ligation were performed depending on individual requirements: ligation of accessory veins (AVL), ligation of the median cubital vein, and temporary banding of the main fistula itself. The determining factor was the appearance of the fistula after each of the procedures was accomplished relative to potential for cannulation. Of these 63 patients with nonfunctional fistulae that ranged in age from 33 to 418 days, access was salvaged in 52 patients (82.5%). This included 9 of 12 patients who required repeat procedures. The results of this study validate angioplasty and AVL as therapy for the salvage of AVFs that fail to develop.

Mechanical thrombolysis for the treatment of thrombosed hemodialysis access grafts.

PURPOSE: To evaluate the data acquired over 2 1/2 years regarding the use of mechanical thrombolysis as the routine, preferred treatment for thrombosed access grafts in a large patient population undergoing hemodialysis. MATERIALS AND METHODS: Mechanical thrombolysis was performed in 1,176 cases. Data were collected on the success rate, complication rate, long-term patency, and presence and location of stenosis. The results of mechanical thrombolysis were compared with those of surgery. All data were collected prospectively. RESULTS: Thrombosed grafts were treated successfully in 1,123 of 1,176 cases (95%). Minor complications occurred in 34 cases (3%). Venous stenosis was present in 1,054 cases (90%). Long-term patency rates were 74% at 30 days, 52% at 90 days, and 17% at 360 days. The thrombosis rate per patient per year and the number of patients who required graft revision or replacement decreased in comparison with the results obtained with surgical treatment. CONCLUSION: Mechanical thrombolysis was effective, quick, and safe. Percutaneous treatment should be adopted as the treatment of choice for thrombosed hemodialysis access grafts.

Thrombolysis versus surgery for the treatment of thrombosed dialysis access grafts.

Thrombolysis offers several advantages over surgery in the treatment of thrombosed dialysis access grafts. This study was undertaken to compare the results obtained when thrombolysis was used as the preferred treatment (Thrombolysis Period) for this problem in comparison with the results that had been obtained when surgical therapy had been the preferred treatment (Surgery Period). Each period of study lasted 12 months and the two periods ran consecutively. All data were collected prospectively. No significant problems were encountered when thrombolysis was substituted for surgical therapy as the preferred treatment of thrombosed dialysis access grafts. During the Surgical Period there were 580 thrombotic episodes, a rate of 0.86 per patient. During the Thrombolysis Period there were 568 episodes, a rate of 0.76. These differences were not statistically significant. During the Thrombolysis Period, thrombolysis was found to be as effective as surgery had been during the Surgical Period in the initial treatment of thrombosed grafts. The rate of surgical revision was decreased by two-thirds during the Thrombolysis Period, but the rate of graft replacement was not altered. Long-term patency after therapy by thrombolysis during the Thrombolysis Period was superior to that for surgical thrombectomy performed during the Surgical Period, and was equal to that for revision and graft replacement. The complication rate for thrombolysis was low and complications were managed easily without sequelae. It is concluded that thrombolysis is safe and, when used as the preferred treatment for thrombosed dialysis access grafts, is as effective as surgical therapy. Since it preserves potential vascular access sites and yields long-term patency rates superior to those for surgical thrombectomy, it should be regarded as the treatment of choice for this problem.

The treatment of vascular access graft dysfunction: a nephrologist's view and experience.

Chronic hemodialysis, as it is practiced today, is heavily dependent on the use of the expanded polytetrafluoroethylene graft for vascular access, although it is prone to the problem of venous stenosis and its sequela, thrombosis. The natural history of untreated venous stenosis is to decrease the efficiency of dialysis and to limit the life expectancy of the graft. Prospective treatment of venous stenosis has been advocated and percutaneous transluminal angioplasty (PTA) has been shown to be safe and reasonably effective for this purpose. Because there is no optimum screening test for venous stenosis, patient selection for PTA is particularly important. The use of a group of clinical indicators that serve to indicate a significant degree of graft dysfunction has been recommended for this purpose. Long-term patency may be better when venous stenosis is surgically revised; however, PTA has a number of advantages, especially the preservation of potential vascular access sites. Endovascular metallic stents have been used to preserve patency following PTA with disappointing results except in selected cases with central lesions. Three types of percutaneous thrombolysis have been studied for the treatment of thrombosed access grafts. The technique of pharmacological thrombolysis in which a lytic enzyme is infused into the clotted graft has proven to be unsatisfactory. The more recently developed technique of pharmacomechanical thrombolysis (PMT) has proven to be practical for use in the dialysis patient. This procedure consists of two components, a pharmacological phase in which lytic enzyme is administered and a mechanical phase in which the residual clot is macerated and removed to restore flow. This technique offers the benefits of being quick, effective, and safe. Additionally, it combines angiographic evaluation of the access, thrombolysis, and angioplasty of stenotic lesions. Mechanical thrombolysis, performed in a manner identical to PMT except that saline is used in place of the lytic enzyme, has been shown to be equally effective and safe.

Mechanical versus pharmacomechanical thrombolysis for the treatment of thrombosed dialysis access grafts.

Pharmacomechanical thrombolysis offers the first practical approach for non-surgical therapy of thrombosed dialysis access grafts. This technique involves both lysis using a fibrinolytic enzyme and mechanical maceration of the clot. The technique can be accomplished in a short period of time, has a high degree of success and has a low level of complications. To evaluate the effectiveness of the mechanical aspects of this technique used alone without the lytic enzyme, a study was designed in which 103 cases of thrombosed PTFE grafts were randomly assigned to either a mechanical (M) group consisting of 55 cases or a pharmacomechanical (PM) group consisting of 48 cases. Both groups were treated in an identical manner using crossed pulse-spray catheters, except that in the M group heparinized saline was used as the pulsing agent while in the PM group concentrated urokinase was used. The two groups were completely comparable in all other respects. The combined procedure of thrombolysis and angioplasty was successful in restoring flow in 92.8% of the M group and 93.8% of the PM group. Life table analysis revealed 74%, 65%, 58% and 37% function in the M group at 15, 30, 60 and 90 days, respectively. The rates for the PM group at the same time intervals were 77%, 72%, 62% and 46%. In none of these parameters was there any significant difference between the two groups. The mean time required for the procedure in the M group was shorter because of the time delay between pulses of enzyme in the PM group built into the technique which was used.(ABSTRACT TRUNCATED AT 250 WORDS)

Gianturco self-expanding stent in the treatment of stenosis in dialysis access grafts.

This study evaluated the effectiveness of the Gianturco endovascular stent in preserving graft patency following percutaneous transvenous angioplasty (PTVA) of stenotic lesions occurring at the graft-vein anastomosis in hemodialysis patients with polytetrafluoroethylene grafts. Fifty-eight patients having 50% or greater stenosis were randomly divided into a treatment group (N = 28) and a concurrent control group (N = 30) following PTVA. In the treatment group, a stent was placed following dilatation. Graft thrombosis, the need for surgical revision, or the need for a repeat PTVA were used as end point events. The period of time from the PTVA/stent procedure to the end point event was referred to as the duration of efficacy (DE). By life table analysis, the DE for the treatment group was 100% at 30 days, 91% at 60 days, 85% at 90 days, 72% at 180 days, and 17% at 360 days. Comparison of the characteristics and results obtained in the treatment group and that of the concurrent control group revealed no significant difference in any parameter prior to treatment, in the response to PTVA, or in the DE of the procedure performed. It was concluded that the stent offered no advantage in the treatment of the graft-vein anastomosis stenotic lesion affecting PTFE dialysis access grafts.

Percutaneous transvenous angioplasty in the treatment of vascular access stenosis.

This study was undertaken to evaluate percutaneous transvenous angioplasty (PTVA) for the treatment of all types of vascular access stenosis in a large population of dialysis patients. Stenoses were identified by venography in patients who met a set of clinical criteria indicating the need for evaluation. The lesions were classified by location and type. Data were collected prospectively and analyzed separately for each lesion type. A total of 536 PTVA procedures was performed in 285 patients. This included 107 cases of long venous stenosis (> 6 cm) and 149 cases of mid-graft stenosis. In the total group, an initial success rate of 94% was obtained (80% or greater dilatation). A decrease in VPm (venous pressure measured on dialysis) of 35.9%, 32.4%, and 22.6% was seen at one week, one month, and three months, respectively. At 90 days, 180 days, and 360 days 90.6%, 61.3%, and 38.2%, respectively, of the treated grafts were continuing to be patent and functional with no need for repeat PTVA treatment. Repeat treatments for recurrent lesions were as successful as the initial treatment. It is concluded that vascular access stenosis can be easily diagnosed and that all categories of stenotic lesion can be effectively treated with PTVA.

Percutaneous venous angioplasty in the treatment of stenotic lesions affecting dialysis fistulas.

A systematic approach was used to detect venous stenotic fistula lesions in a large dialysis population. All significant stenoses were treated with percutaneous venous angioplasty (PTVA). A total of 380 PTVAs were done in 241 patients. It was possible to dilate 96% of lesions successfully. A complication rate of 3.4% was seen, and only two fistulas were lost. Patient follow-up consisted of monitoring percent decrease in venous resistance (VR) and determining long-term patency. The VR was decreased 35.4% at 1 week and 23.5% at 3 months; 58% of the treated fistulas continued to be patent at 6 months, and 35% at 12 months. It was concluded that PTVA can prolong the life of hemodialysis fistulas successfully with a low level of complications. The lesions tend to recur, but they can be retreated successfully, obviating surgery and preventing the depletion of potential vascular access sites.

The use of the Gianturco intravascular stent in stenotic hemodialysis fistulas.

This study was initiated to investigate the use of the Gianturco intravascular stent in prolonging dialysis access graft patency after angioplasty. Stents were placed in 25 patients with follow-up to date of 0.5-8 months. The stent used was 1.5 x 3 cm and consisted of two units connected by a single strut. In Phase 1, the strut was rigid, and the stent had no barbs. The rigidity of the stent and stent migration caused problems. In Phase 2, an articulated strut design was used, and in Phase 3, barbs were added. These modifications solved the previously noted problems. No anticoagulation was used, and clotting was not a significant problem. The duration of patency for the total group was not significantly better than for control groups. However, there were no losses with the modified stent design used in Phases 2 and 3 with follow-up to date of 0.5-5.5 months. Further study of this treatment modality appears warranted.

Development of the characteristic ultrastructural lesion of hereditary nephritis during the course of the disease.

The diagnosis of hereditary nephritis in the absence of a clear family history or the presence of characteristic ancillary abnormalities is difficult, but it has considerable prognostic importance. The recent recognition of an ultrastructural lesion characteristic of this disease, although not present in all families, is of considerable value. In this report we describe a kindred with the lesion-associated disease that differs from those previously described in that the lesion developed during the course of the disease, was not present in all affected members and appeared to be the result of paternal transmission.

Nephronophthisis. Renal function and histologic studies in a family.

Nephronophthisis (previously described as familial juvenile nephronophthisis and medullary cystic disease) is characterized by insidious renal failure, its main features being increased urinary sodium loss, pitressin-resistant hypotomic polyuria, polydipsia, normal urine sediment and absence of hypertension. Renal function and histologic studies were performed in a family in which two siblings had this disorder, while the parents and two other siblings appeared clinically normal. Both parents demonstrated a moderate impairment of maximum urinary concentration. The values for tubular free water reabsorption (TcH2O) were relativley normal in the parents and the healthy siblings. One of the index patients showed only minimal sodium wasting even though he had hyposthenuria, thus suggesting an involvement of the collecting ducts in the early stage of neophronophthisis. No evidence of proximal tubular dysfunction was found. Although the light-microscopic examination of renal biopsies from the parents and the healthy siblings was unremarkable, electron microscopy revealed probable abnormalities in all four. An autosomal recessive mode of inheritance is, therefore, suggested in this family. The etiology of nephronophthisis is obscure but a likely possibility is that the renal damage results from an inborn metabolic error.