[The role of the von Willebrand factor in renal diseases and haemodialysis patients]. / Bioloskata aktivnost na fon Vilebranodoviot faktor kaj bubrezni i hemodijalizni bolni.

During a period of twenty years, the von Willebrand factor (VWf) biological activity was evaluated in 805 patients with vein thrombosis, diabetes mellitus, chronic renal failure and ischemic heart disease. The examined patients were 168 with vein thrombosis, 129 with diabetes mellitus, 412 with chronic renal failure (CRF), and 96 with ischemic heart disease. The biological activity was also determined in 104 haemodialysis patients using four different haemodialytic membranes: 30 on cuprophan membrane, 30 on polymethylmetacrylate membrane (PMMA), 24 on hemophane and 20 patients on polysulphone (PS) membrane. In 42 patients with arterio-venous fistula prone to thrombosis, the biological activity of the von Willebrand Factor was 178% in comparison to 106% in the control group. The biological activity of VWF was increased in patients with vein thrombosis (p < 0.02), in patients with diabetes mellitus (p < 0.01), CRF (p < 0.05), and in patients with ischemic heart disease (p < 0.01). The highest biological activity was found in patients on PMMA (p < 0.001), then cuprophan (p < 0.05) and hemophane membrane (p < 0.01), while the lowest increase of its concentration was noticed in patients on PS without statistical significance. In arteriovenous fistula prone to thrombosis patients biological activity of the von Willebrand Factor was significantly increased (p < 0.01). Our investigations show the importance of VWF as a marker of endothelial disfunction, a possible predictor of A-V fistula thrombosis, and a possible marker of haemodialysis membranes biocompatibility.

Approach to vascular access for hemodialysis: experiences from the Republic of Macedonia.

Eight thousand eight hundred and forty nine different vascular hemodialysis accesses were performed in the period from 1976 until 1999 at the Department of Nephrology, Skopje: 3,114 native arterial-venous fistula (AVF), 715 arterial-venous shunts (AVS), 4,964 temporary or permanent catheters (4,411/88.86% femoral, 410/8.26% subclavian, 143/2.88% jugular) and 56 PTFE vascular grafts. Femoral catheterization (4,312/86.86%) is the favoured solution if a temporary vascular dialysis access is taken into consideration. The most popular chronic dialysis angio-access in our country is native AVF (90.5% of 3,440 permanent dialytic vascular accesses). The tunneled subcutaneously positioned catheters as a permanent dialytic angio-access were present in 270 cases (7.9%): 99 in femoral veins (our original method), 123 in subclavian veins and 48 catheters in jugular veins. The synthetic vascular grafts-PTFE (polytetrafluoro-ethylene) represent only 1.6% of all dialysis angio-accesses. The number of preventive AVFs created in patients with preterminal end-stage renal disease eventually increased; from 14% in the eighties, 20.8% after 10 years and 31.50% in 1999. Most of the preventive AVFs are done in outpatients 71.8% in 1999. This year 44.4% of all chronic vascular access were created in the same way. We prefer femoral catheters for both temporary and permanent access because our results show that femoral catheterization has a lower rate of early complications when compared to the subclavian catheterization group; the rate of late complications (thrombosis, stenosis, infections) is lower or the same; infections in femoral catheterizations are less frequent, compared to subclavian and jugular ones. Our contributions in the field of vascular access surgery are the three original methods which are constantly used at the Department: 1. Combination of temporary (AVS) and permanent vascular access (AVF) using the same blood vessels, performed in one surgical act; 2. Tunneled femoral catheter as a permanent vascular access for hemodialysis (2 types: on the abdominal wall and on the infrainguinal region - thigh); 3. Reduction of hyper-flow in AVF without the operation of "banding", with ligation of the artery before arteriovenous anastomosis.

Are ambulatory femoral catheters for hemodialysis a safe vascular access?

Femoral catheterization is fast and simple and associated with a low risk of complications. Those which occur can usually be managed easily. Femoral catheters are usually kept in place for a short period of a few days. We, instead, used femoral catheters (FC) as a temporary vascular access for a longer period of time (until the permanent vascular access matured) in inpatients and in outpatients on regular ambulatory hemodialysis who had a problem with their permanent access. We analyzed 59 patients with end-stage renal disease treated with hemodialysis (HD), divided into two groups. Of the group that started with hemodialysis (group I), only 16 patients were hospitalized during the maturation of native arterio-venous fistula (AVF). Duration time of the catheters was 15-47 days (average 32 days). The second group (group II) comprised 43 patients going on regular ambulatory hemodialysis who were discharged from hospital with femoral catheters. Duration time of catheters in this group was 13-183 days (average 44.2 days). Catheters were removed when AVF matured, or if a significant complication occured. We took blood culture from peripheral vein (BCP) and from catheter (BCC) on removal of the catheter, or when we suspected infection. Catheter tips (CT) were also sent for microbiological analysis. We monitored the clinical signs of infection. We compared microbiological results of BCP, BCC and CT from the two groups using chi-square test and we did not find any significant difference among the three types of findings (p<0.05). The FC was removed from one patient only from group II because of suspicion of catheter-related infection. Two pts were treated with antibiotics (AB) systemically and locally (AB was 'locked' in the catheter) because of febricity. When the catheters were removed the microbiological findings were sterile. We concluded that FC can be used without any problem for a longer period of time for ambulatory HD, with the provision of permanent care from a team specially trained for vascular access.

Atherosclerosis risk factors related to hemodialysis duration and erythropoietin therapy.

Patients undergoing hemodialysis are at risk for atherosclerosis and its complications. The aim of this study was to examine the effect of erythropoietin therapy and hemodialysis duration on some of the atherosclerotis risk factors. The patients were divided into four groups: I: patients undergoing hemodialysis for less than 10 years (n=22); II: patients undergoing hemodialysis for more than 10 years (n=17); III: patients on no erythropoietin (n=21); IV: patients on erythropoeitin therapy (n=18). A control group of 20 subjects was also examined. Triglycerides, total cholesterol, low-density lipoprotein and high-density lipoprotein, lipoprotein(a), apolipoprotein-A1, apolipoprotein-B and lipid peroxidation were examined. There was a significant increase in triglycerides, to 2.59+/-1.2 mmol/l (p<0.001) and in lipid peroxidation in hemodialysis patients, to 5.02+/-0.9 micromol/l vs. controls (p<0.001). Significantly elevated triglycerides and lipid peroxidation levels were found in the patients with longer hemodialysis duration. Triglycerides were elevated in group II vs. group I, to 2.90+/-1.0 mmol/l. (p<0.05). Lipid peroxidation in group II, 5.40+/-1.0 micromol/l, showed significant difference compared to group I (p<0.05). Erythropoietin treatment did not affect any of the examined parameters. These results indicate increased risk for atherosclerosis related to hemodialysis duration. Besides the renal disease itself, hemodialysis may also be one of the risk factors for atherosclerosis.

[Vascular access and chronic renal failure]. / Accès vasculaires et insuffisance rénale chronique.

From 1976 to 1999 a total of 8,849 surgical procedures for vascular access prior to dialysis were performed in the Department of nephrology at Skopje hospital (Macedonia). Cases included 3,114 native arteriovenous fistula (AVF), 715 arteriovenous shunts and 4,964 temporary or indwelling catheters (4,411 (88.86%) in the femoral vein, 410 (8.26%) in the subclavian vein, 143 (2.88%) in the jugular vein and 56 PTFE vascular grafts). Femoral catheterization is the favoured solution for repeated dialysis (90.50% of the 3,440 procedures for indwelling vascular access). Subcutaneous indwelling catheters were used in 270 (7.90%) cases, with vascular access taking place in either the femoral (99 cases), subclavian (123 cases) or jugular vein (48 cases). Biosynthetic vascular grafts represent only 1.6% of all procedures for vascular access. The number of preventive AVFs has been increasing steadily from 14% in the 1980s to 20.8% in the 1990s and 31.50% in 1999. The majority of preventive AVFs (71.80%) and a large number of other surgical procedures for vascular access (44.40%) are performed in day hospital.