Arteriovenous Fistula Thrombosis Research Articles

Analysis on the Causes and Nursing Care of Thrombosis of Arteriovenous Fistula in Maintenance Hemodialysis Patients

Analysis on the Causes and Nursing Care of Thrombosis of Arteriovenous Fistula in Maintenance Hemodialysis Patients

A comparison of arteriovenous fistula failure between Malaysian and Australian and New Zealand participants enrolled in the FAVOURED trial.

To describe and compare de novo arteriovenous fistula (AVF) failure rates between Australia and New Zealand (ANZ), and Malaysia. AVFs are preferred for haemodialysis access but are limited by high rates of early failure. A post hoc analysis of 353 participants from ANZ and Malaysia included in the FAVOURED randomised-controlled trial undergoing de novo AVF surgery was performed. Composite AVF failure (thrombosis, abandonment, cannulation failure) and its individual components were compared between ANZ (n = 209) and Malaysian (n = 144) participants using logistic regression adjusted for patient- and potentially modifiable clinical factors. Participants' mean age was 55 ± 14.3 years and 64% were male. Compared with ANZ participants, Malaysian participants were younger with lower body mass index, higher prevalence of diabetes mellitus and lower prevalence of cardiovascular disease. AVF failure was less frequent in the Malaysian cohort (38% vs 54%; adjusted odds ratio (OR) 0.53, 95% confidence interval (CI) 0.31-0.93). This difference was driven by lower odds of cannulation failure (29% vs 47%, OR 0.45, 95% CI 0.25-0.80), while the odds of AVF thrombosis (17% vs 20%, OR 1.24, 95% CI 0.62-2.48) and abandonment (25% vs 23%, OR 1.17, 95% CI 0.62-2.16) were similar. The risk of AVF failure was significantly lower in Malaysia compared to ANZ and driven by a lower risk of cannulation failure. Differences in practice patterns, including patient selection, surgical techniques, anaesthesia or cannulation techniques may account for regional outcome differences and warrant further investigation.

The role of vacuum-assisted mechanical thrombectomy in the management of acutely thrombosed arteriovenous fistulas and grafts.

The purpose of this study is to evaluate the safety and efficacy of the mechanical thrombectomy with the Indigo System in the treatment of thrombosed arteriovenous fistulas and grafts. A retrospective search of endovascular procedures performed from November 2018 to June 2020 was conducted. Inclusion criteria were: acute arteriovenous fistula or graft thrombosis that underwent endovascular mechanical thrombectomy with Indigo System. The following information was collected from each case: sex, age, fistula modality, fistula location, treatment modality, and outcomes. Endpoints evaluated were: technical and clinical success rates; primary, assisted primary, and secondary patency rates; complication rates. Twenty-six mechanical thrombectomy procedures for declotting of arteriovenous fistula thrombosis, using the Indigo System, were performed in 22 patients. Technical and clinical success was achieved in 23/26 cases (88%). Mean follow-up was 9 months (range 11-539 days). The 6-month primary, primary assisted, and secondary patency rates were 71%, 86%, 93% and the 12-month primary, primary assisted, and secondary patency rates were 71%, 72%, 80%, respectively. No technical or device-related complications were observed during thrombectomy, however two venous ruptures occurred on the angioplasty of the underlying stenosis. In conclusion, vacuum-assisted thrombectomy of acutely thrombosed arteriovenous fistulas and grafts with Indigo System is safe and effective, providing good short term patency rates.

Ruptured dural arteriovenous fistula and sinus venous thrombosis following surgical resection of a vestibular schwannoma: Case report and review of the literature

Dural arteriovenous fistula (DAVF) is a rare vascular malformation. Strong evidence suggests that the development of DAVF in adults is acquired and multifactorial.The link between cerebral venous thrombosis and DAVF is probably explained by dynamic changes in the venous drainage pattern.We report the case of a 34-year-old man admitted to the emergency department for seizure and headaches. The patient had a medical history of right vestibular schwannoma resection 9 months earlier, complicated by untreated asymptomatic sigmoid sinus thrombosis.At admission, CT scan revealed a spontaneous temporal intracerebral hemorrhage associated with ventricular hemorrhage due to the rupture of a DAVF diagnosed by complementary CT angiography.External ventricular drainage was performed in emergency, followed by endovascular exclusion of the DAVF. Good neurological outcome was achieved, with complete exclusion of the vascular malformation.This clinical case underlines the absence of guidelines on the use of anticoagulation drugs to treat postoperative venous sinus thrombosis and to potentially prevent DAVF as a late complication following cerebellopontine angle surgery.

Safety and Efficacy of the CELT ACD Femoral Arteriotomy Closure Device in the Office-based Laboratory

Manual compression remains the gold standard for achieving hemostasis for percutaneous common femoral artery access. However, it requires prolonged bed rest and 20-30 minutes or more of compression for hemostasis. Current arterial closure devices have emerged in recent years, but they are still associated with significant access device complications, including hematoma, retroperitoneal bleeding, transfusion requirement, pseudoaneurysm, arteriovenous fistula, and arterial thrombosis. A novel femoral access closure device, the CELT ACD (Vasorum Ltd), has been previously shown to reduce these complication rates and allow rapid hemostasis and time to ambulation and discharge.

Effect of the combination of percutaneous transluminal angioplasty and pharmacological thrombolysis on hemodialysis patients

Purpose: To examine the efficacy of percutaneous transluminal angioplasty (PTA), combined withpharmacologic thrombolysis (PT) on thrombosis of autologous arteriovenous fistulas (AVFs),inflammatory factors, and β2 microglobulin (β2-MG) levels in hemodialysis patients.Methods: Seventy-eight patients with AVF thrombosis allocated randomly into a control group (CG) received PTA, and a study group (SG) received PTA combined with PT (n = 39 in each). The patency, vascular condition, inflammatory factors, viz, interleukin-6 (IL-6), high-sensitivity C-reactive protein (hs-CRP)), β2-MG levels, vascular-related factors (VEGF-A and MCP-1), complications, and quality of life were determined.Results: At three and six months after surgery, t SG exhibited a higher vascular patency than CG (p <0.05). Serum levels of IL-6, hs-CRP, β2-MG, VEGF-A, and MCP-1 of t SG were lower than those of CG(p < 0.05). The SG showed higher cross-sectional area, inner diameter at the site of fistula, and better quality of life scores than CG (p < 0.05).Conclusion: The combination of PTA and PT enhances efficacy, increases vascular patency, reduces inflammatory response, lowers the level of β2-MG, and improves quality of life in patients with AVFs without increasing complications. Thus, the combination treatment has potentials for the management of hemodialysis patients.

Successful endovascular recanalization of a thrombosed arteriovenous fistula with extensive stenosis

Management of chronic arteriovenous fistula (AVF) thrombosis is challenging. In this case report, we described successful endovascular treatment for a thrombosed AVF with extensive stenosis. A 50-year-old woman presented with diminishing blood flow of her forearm AVF. Diagnostic angiogram showed a long segment of cephalic vein outflow stenosis, occlusion of one accessory cephalic vein branch, and proximal stenosis of the cephalic vein. After angioplasty, the occluded fistula was recanalized without any significant residual stenosis. The AVF had been functional at 6-month follow-up.

The Longitudinal Evolution of Post–COVID-19 Outcomes Among Hemodialysis Patients in Turkey

IntroductionHemodialysis (HD) patients have increased risk for short-term adverse outcomes of COVID-19. However, complications and survival at the post–COVID-19 period have not been published extensively.MethodsWe conducted a national, multicenter observational study that included adult maintenance HD patients recovered from confirmed COVID-19. A control HD group without COVID-19 was selected from patients in the same center. We investigated the characteristics and outcomes in the follow-up of HD patients and compare them with the non–COVID-19 group.ResultsA total of 1223 patients (635 patients in COVID-19 group, 588 patients in non–COVID-19 group) from 47 centers were included in the study. The patients' baseline and HD characteristics were almost similar. The 28th-day mortality and mortality between 28th day and 90th day were higher in the COVID-19 group than non–COVID-19 group (19 [3.0%] patients vs. none [0%]; 15 [2.4%] patients vs. 4 [0.7%] patients, respectively). The presence of respiratory symptoms, rehospitalization, need for home oxygen therapy, lower respiratory tract infection, and arteriovenous (AV) fistula thrombosis was significantly higher in the COVID-19 group in both the first 28 days and between 28 and 90 days. In the multivariable analysis, age (odds ratio [OR] [95% CI]: 1.029 [1.004–1.056]), group (COVID-19 group vs. non–COVID-19 group) (OR [95% CI]: 7.258 [2.538–20.751]), and vascular access type (tunneled catheter/AV fistula) (OR [95% CI]: 2.512 [1.249–5.051]) were found as independent parameters related to 90-day mortality.ConclusionIn the post–COVID-19 period, maintenance HD patients who have had COVID-19 have increased rehospitalization, respiratory problems, vascular access problems, and high mortality compared with the non–COVID-19 HD patients.

Transcriptomic Analysis Identifies Differentially Expressed Genes Associated with Vascular Cuffing and Chronic Inflammation Mediating Early Thrombosis in Arteriovenous Fistula.

Arteriovenous fistula (AVF) is vascular access created for hemodialysis in end-stage renal disease patients. AVF creation causes increased blood flow in the outflow vein with increased pressure. Increased blood flow, blood volume, and shear stress causes outward remodeling so that the outflow vein can withstand the increased pressure. Outward remodeling of the vein involved in AVF is necessary for AVF maturation, however, inward remodeling due to excessive neointimal hyperplasia (NIH) and chronic inflammation may end up with vessel thrombosis and AVF maturation failure. Early thrombosis of the vessel may be due to the luminal factors including NIH and chronic inflammation or due to chronic inflammation of the adventitial due to perivascular cuffing. Inflammation may either be due to an immune response to the vascular injury during AVF creation or injury to the surrounding muscles and fascia. Several studies have discussed the role of inflammation in vascular thrombosis due to intimal injury during AVF creation, but there is limited information on the role of inflammation due to surrounding factors like a muscle injury. The concept of perivascular cuffing has been reported in the nervous system, but there is no study of perivascular cuffing in AVF early thrombosis. We performed the bulk RNA sequencing of the femoral arterial tissue and contralateral arteries as we found thrombosed arteries after AVF creation. RNA sequencing revealed several significantly differentially expressed genes (DEGs) related to chronic inflammation and perivascular cuffing, including tripartite motif-containing protein 55 (TRIM55). Additionally, DEGs like myoblast determination protein 1 (MYOD1) increased after muscle injury and relates to skeletal muscle differentiation, and network analysis revealed regulation of various genes regulating inflammation via MYOD1. The findings of this study revealed multiple genes with increased expression in the AVF femoral artery and may provide potential therapeutic targets or biomarkers of early thrombosis in AVF maturation failure. Thus, not only the luminal factors but also the surrounding factors mediating vascular cuffing contribute to vessel thrombosis and AVF failure via early thrombosis, and targeting the key regulatory factors may have therapeutic potential.

Heterogeneous Population of Immune cells Associated with Early Thrombosis in Arteriovenous Fistula.

End-Stage Renal Disease (ESRD) is a growing cause of morbidity and mortality in the practice of modern medicine. Advances in medicine have elongated the average life span and subsequently made chronic diseases prevalent. Hemodialysis is the main treatment that is used to treat ESRD and is a clinical procedure that is being re-imagined with novel approaches to improve patient and clinic practicality and effectiveness. Arteriovenous Fistulas (AVF) are now used in place of catheters due to their higher success and lower co-morbidities. The main drawback of AVF is the time gap that is needed from the surgical creation of AVF to its use. During this time, the AVF is susceptible to thrombosis and occlusion rendering the fistula ineffective for treatment. Immune cells play a major role in vascular pathologies and macrophages, dendritic cells, and T-regulatory cells are the main cells seen during the inflammatory and anti-inflammatory phases. However, the role of immune response and immune cells in AVF maturation is poorly understood. This study aimed to investigate the immune response and immune cell expression in femoral vessels after AVF creation in a miniswine model of AVF using immunohistochemistry and qRT-PCR. The results of this study revealed an increased expression of immune cells in AVF vessels and suggest an association of immune response with AVF creation and maturation.

TLR-4 Inhibition Attenuates Inflammation, Thrombosis, and Stenosis in Arteriovenous Fistula in Yucatan Miniswine.

Arteriovenous fistula (AVF) is the preferred vascular access in hemodialysis patients; however, it is afflicted with a high failure rate. Chronic inflammation, excessive neointimal hyperplasia (NIH), vessel stenosis, early thrombosis, and failure of outward remodeling are the major causes of AVF maturation failure. Inflammatory mediator toll-like receptor (TLR)-4 plays a critical role in NIH, arterial thrombosis, and stenosis. We investigated the effect of TLR-4 inhibition on early thrombosis. Yucatan miniswine were used to create AVF involving femoral artery and femoral vein and treated with TLR-4 inhibitor TAK-242 with ethanol as the vehicle. The vessels were assessed after 12 weeks using histomorphometry, immunostaining, ultrasound, angiography, and optical coherence tomography. Inhibition of TLR-4 attenuated inflammation and early thrombosis in 50% of animals, and blood flow was present through AVF in 25% of animals. Thus, targeting TLR-4 to attenuate inflammation and early thrombosis might be a therapeutic approach to keep AVF patent and maintain blood flow through the outflow vein.

Application Value and Relevance Analysis of the Risk Evaluation System for Arteriovenous Fistula Puncture in Thrombosis after Puncture.

Objective To analyze the application value and relevance of risk evaluation system for arteriovenous fistula (AVF) puncture in thrombosis after puncture. Methods The clinical data of 180 patients treated with hemodialysis in the hemodialysis center of our hospital from November 2017 to November 2019 were retrospectively analyzed. After puncture, all patients received the digital subtraction angiography (DSA) examination, and based on whether they had AVF thrombosis, they were divided into the nonthrombosis group (n = 102) and thrombosis group (n = 78), and then, according to the parity of their admission numbers, the patients in the thrombosis group were subdivided into the study group (n = 39) and the reference group (n = 39), so as to analyze the risk factors of thrombosis after AVF puncture and the application value of the risk evaluation system for AVF puncture in preventing and treating thrombosis. Results Compared with the reference group after intervention, the study group had significantly higher mean internal fistula blood flow volume (P < 0.001) and significantly lower total incidence rate of vascular complications in fistulas (P < 0.05); according to the multifactor binary logistic regression analysis, it was found that diabetes, systolic blood pressure reduction, hemoglobin, low-density lipoprotein cholesterol (LDL-C), ultrafiltration rate, and elevation of blood phosphorus and platelet levels were the risk factors of thrombosis after AVF puncture in hemodialysis patients. Conclusion When risk factors of thrombosis are found in patients treated with hemodialysis, timely detection and intervention shall be applied in the early stage. Adopting the AVF puncture risk evaluation system has an extremely high application value in the clinic and is of important meaning in prolonging the service life of fistulas.

Case report of a near-fatal case of Mycobacterium massiliense sepsis after de-clotting of an arteriovenous fistula

BackgroundMycobacterium massiliense is a rapidly growing a non-tuberculous mycobacterium that has been validated as a separate species from the Mycobacterium abscessus group. Only few antibiotics have demonstrated germicidal activity against Mycobacterium massiliense, and some of those include amikacin, clarithromycin, and cefoxitin.Case presentationWe present the first reported case of near-fatal septic shock caused by disseminated Mycobacterium massiliense after de-clotting of an infected arteriovenous fistula, in a patient with end-stage renal disease with concomitant human immunodeficiency virus infection. Early recognition of the culprit organism and treatment with a combination therapy of clarithromycin and amikacin led to rapid improvement.ConclusionThis unique case can highlight the importance of taking into consideration Mycobacterium massiliense infection as a cause of arteriovenous fistula thrombosis and highlights the risk of disseminated infection leading to life threatening sepsis upon de-clotting of the fistula.

Hemodialysis Patients with Higher Serum Levels of Soluble Receptor for Advanced Glycation End Products Have an Increased Risk for Arteriovenous Fistula Failure

Background: Arteriovenous fistula (AVF) failure due to thrombosis is a major cause of morbidity in patients undergoing regular hemodialysis (HD). Advanced glycation end products (AGEs) and their receptor (RAGE) might contribute to inflammation, neointimal hyperplasia, and thrombosis. RAGE has a C-truncated secretory receptor form, called soluble RAGE (sRAGE). In this study, we aimed to evaluate the association of serum sRAGE with AVF failure due to thrombosis in HD patients. Methods: Eighty-eight prevalent HD patients with functional AVF were included in the study. The presence of stenosis, clinical and laboratory data, and serum sRAGE was evaluated at inclusion. sRAGE concentration was measured by a competitive enzyme-linked immunosorbent assay, and stenosis was detected by ultrasound. Patients were prospectively followed up for 36 months. During this period, AVF failure (defined as the absence of blast or palpable thrill and impossible cannulation with 2 needles because of complete thrombosis) was noted and thrombosis was certified by ultrasound examination. Results: During follow-up, 16 (18.18%) patients lost their vascular access due to thrombosis. In multivariate Cox regression analysis, sRAGE was a significant predictor of vascular access thrombosis (hazard ratio = 1.15, 95% confidence interval: 1.03–1.25, p = 0.012). Kaplan-Meier analysis showed a significantly lower AVF patency time in patients with sRAGE >16.78 ng/mL than those with sRAGE <16.78 ng/mL (p = 0.02). In the subgroup of patients with stenosis at baseline, sRAGE, serum albumin, obesity, and ischemic heart disease were associated with thrombosis. Conclusion: In our study, baseline, systemic sRAGE is associated with the occurrence of thrombosis of AVF, and this marker has a significant impact on AVF survival.

Effect of Systemic Intraoperative Heparin Use on Upper Extremity Arteriovenous Fistula Patency in End-Stage Renal Disease Patients.

The formation of the arteriovenous fistula is an important method of vascular access for patients with end-stage renal disease (ESRD). This allows renal filtration resulting in improved life quality and expectancy for ESRD patients. The biggest drawback to arteriovenous fistula formation is thrombosis, which can occur at an early or delayed stage. One suggested method of reducing postoperative arteriovenous fistula thrombosis rates is the administration of intraoperative systemic heparin. Heparin use in this context is debated, and there is currently no consensus on its use. There are a number of small randomised control studies trialling use of heparin but no large systematic trials. In this report, we collate existing evidence in the form of a review article and attempt to extrapolate a consensus of the evidence.

A national cohort study on hemodialysis arteriovenous fistulas after kidney transplantation - long-term patency, use and complications

ObjectiveTo describe the long-term hemodialysis arteriovenous fistula (AVF) patency, incidence of AVF use, incidence and nature of AVF complications and surgery in patients after kidney transplantation.Patients and methodsWe retrospectively analysed the AVF outcome and complications in all adult kidney allograft recipients transplanted between January 1st, 2000 and December 31, 2015 with a functional AVF at the time of transplantation. Follow-up was until December 31, 2019.ResultsWe included 626 patients. Median AVF follow-up was 4.9 years. One month after kidney transplantation estimated AVF patency rate was 90%, at 1 year it was 82%, at 3 years it was 70% and at 5 years it was 61%; median estimated AVF patency was 7.9 years. The main cause of AVF failure was spontaneous thrombosis occurring in 76% of AVF failure cases, whereas 24% of AVFs were ligated or extirpated. In a Cox multivariate model female sex and grafts were independently associated with more frequent AVF thrombosis. AVF was used in about one third of our patients. AVF-related complications occurred in 29% of patients and included: growing aneurysms, complicated thrombosis, high-flow AVF, signs of distal hypoperfusion, venous hypertension, trauma of the AVF arm, or pain in the AVF/arm.ConclusionsAVFs remain functional after kidney transplantation in the majority of patients and are often re-used after graft failure. AVF-related complications are common and require proper care.

The management of dialysis access thrombosis during the COVID-19 pandemic.

Maintaining patent access is essential for haemodialysis dependent end stage renal failure patients. The COVID-19 pandemic has significantly affected surgical and interventional radiology services worldwide. We aimed to review the impact COVID-19 has caused to the management of acute dialysis access thrombosis. We conducted a single centre retrospective review of outcomes of patients with arteriovenous fistula and arteriovenous graft thrombosis between March and May 2020, which coincided with the first peak of the COVID-19 pandemic in London, and a similar period in the previous year, March-May 2019. Outcomes in both cohorts of patients were compared, including attempts at salvage, salvage success, 1-month patency rates after salvage and subsequent surgery on the same access. We also analysed the use of tunnelled haemodialysis lines (THL), either due to failed salvage attempts or when salvage was not attempted. There was a similar incidence of access thrombosis in both periods (26 cases in 2019, 38 in 2020). There were 601 patients dialysing via an arteriovenous fistula or graft in 2019, and 568 patients in 2020. Access salvage, when attempted, had similar success rates and 1-month patency (salvage success 74% vs 80%, p = 0.39; 1-month patency 55% vs 62%, p = 0.69). The proportion of patients where access salvage was not attempted and a THL inserted was significantly higher in 2020 compared to 2019 (32% vs 4%, p = 0.007). There were more patients who subsequently had surgery to salvage or revise the same access in 2019 compared to 2020 (62% vs 13%, p < 0.001). During the peak of the COVID-19 pandemic, there were fewer attempts at access salvage. This was a conscious decision due to increased pressure on the healthcare system, access to emergency interventional radiology or operative theatres and the perceived risk/benefit ratio of access salvage. The long-term effects of this change in practice remain unknown.

THE I NFLUENCE OF INTRАDIАLYTIC HYPOTENSION ON THE FUNCTIONING OF АRTERIOVENOUSFISTULА

Introduction. Nowadays hemodialysis is the most widespread way of treatment concerning the end-stage renal disease. The variant of choice as for permanent vascular access for hemodialysis is arteriovenous fistula. An actual problem is the deterioration of the patency of arteriovenous fistula. According to the research, most patients do not know about the risks associated with intradialytic hypotension. Under these conditions, research with determining the level of critical intradialytic hypotension is particularly relevant.&#x0D; Purpose of the work is to study and evaluate intradialytic hypotension as a risk factor for thrombosis of arteriovenous fistulas.&#x0D; Materials and methods. 60 patients were examined with end-stage renal disease, receiving of hemodialysis. Among these patients a thrombosis of arteriovenous fistula appeared in the long term (7.5 (3.0–17.6) months) after the surgery. The average age of patients was (54.1 ± 11.8) years; there were 30 (50%) men, 30 (50%) women.&#x0D; Results. According to the results of our study, 38 (63 %) patients had hypotension at the end of the hemodialysis session.&#x0D; Conclusions. Blood hypotension is one of the main predictors of thrombosis of arteriovenous fistula in the late postoperative period. A decrease in systolic blood pressure on 35.0 (25.0–50.0) mm Hg to 100.0 (90.0–110.0) mm Hg is critical for the patency of arteriovenous fistula. Adequate control and correction of blood pressure (in particular, during a hemodialysis session) can prevent thrombosis of arteriovenous fistula.

Effects of plasma atherogenic index and plasma osmolality on arteriovenous fistula patency in hemodialysis patients.

The purpose of the present study was to investigate the effects of Plasma atherogenic index (AIP) and plasma osmolality (PO) values on arteriovenous fistula (AVF) patency in patients with chronic renal failure. The patients with primary AVF between December 2012 and March 2020 with the diagnosis of end-stage renal disease in our clinic were included in the study. The patient data were collected retrospectively in digital medium. Diabetic patients were not included in the study. The Triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), sodium (Na), fasting blood glucose, and blood urea nitrogen (BUN) values were found and recorded from the files. AIP and PO were calculated with special formulas. Fistula patency rate in 6th, 12th, and 24th months were evaluated in 2-year follow-ups. According to the results of two-year follow-ups of the 162 patients, who underwent primary AVF, 21 (13%) patients were found to have thrombosis in the 6th month, 33 (20.4%) patients in the 12th month; however,141 (87%) and 129 (79.6%) patients actively used AVF in the 6th and 12th months, respectively. The AIP and PO values that were calculated in the patient group with AVF thrombosis were significantly higher (p = 0.001, p < 0.001; respectively). In the multivariate logistic regression analysis, Na, BUN, and HDL-C variables were found to be independent predictive factors for AVF thrombosis (OR (Odds Ratio): 1.169, 95% CI (Confidence interval)): 1.056-1.294, p = 0.003; OR: 1.108, 95% CI: 1.043-1.176, p = 0.001; OR: 0.874, 95% CI: 0.820-0.932, p < 0.001; respectively). It was also found that the patency rate was 64.2% (104 patients) in the 24th month. AIP, PO, Na, and BUN values are positively associated with AVF thrombosis. Checking AIP, Na, and BUN values will be useful in patients with end-term renal failure, who already have difficulties in renal replacement methods and vascular access.

MO772PRIMARY AND SECONDARY HYPEROXALURIA IN CHRONIC DIALYSIS PATIENTS: FOCUS ON VASCULAR ACCESS

Abstract Background and Aims Hyperoxaluria is a rare metabolic disorder chacterized by widespread calcium oxalate deposition, if plasmatic oxalate level (pOx) overcomes saturation threshold. It could be primary (PH), a recessive disease associated with mutation of the liver enzyme LDH, or secondary (SH), in 75% due to intestinal malabsorption. Urolithiasis could be the first complication, and renal involvement could progress until end-stage renal disease (ESRD). Mean pOx is higher in chronic dialysis patients than healthy individuals because of impaired renal clearance. Oxalate molecular weight (MW) is 88 Da and its clearance is that of low MW uremic toxins. Our aim is to assess an association between arteriovenous fistula (AVF) failures and Hyperoxaluria. Method In the period between 1/1/2004 and 12/31/2020, diagnosis of Hyperoxaluria was carried out in 6 patients out of 1530 chronic dialysis patients (0.39%). The median age of patients was 65.5 [26-72] years, the male/female ratio was 3:3 and the median dialysis vintage was 36 [1-181] months. Three patients come to nephrological referral at stage 5 of CKD while 1 patient came to Italy when chronic HD was already started. At that time pOx was not considered. In these 4 patients the presumptive diagnosis of ESRD was urolithiasis and diagnosis of Hyperoxaluria was carried out after the beginning of chronic dialysis, when pOx and genetic analysis were performed. In 1 case biopsy on the kidney graft and in 1 case kidney biopsy after nephrectomy were performed: oxalate deposition was detected. For 2/6 patients diagnosis was carried out after biopsy of native kidneys before starting dialysis. All patients started medical therapy for hyperoxaluria. Five out of 6 patients were eligible to HD, 1/6 to PD. AVF was judged the first choice vascular access. Results PH was diagnosed in 3/6 patients: mutations were detected on chromosome 2. Malabsorption secondary to short bowel syndrome and chronic pancreatitis could be assumed as causes of SH in 3 patients. Patient 1 underwent 2 combined liver-kidney transplantation: the first failed by arterial grafts thrombosis and the second by renal primary non-function but the liver was still functioning, he died on HD after 12 years. Patient 2 underwent liver and kidney transplantation and she is nowadays dialysis-free. The median pOx pre-dialysis and before diagnosis was 165 [98-259] umol/L (Table 1). Patients on chronic HD underwent median of 3 [2-5] AVF interventions. Nine AVFs were distal and 4 were proximal. The most frequent complication was AVF thrombosis despite ASA treatment: half of the cases showed secondary AVF non-function, the other half of AVFs failed to mature. Six tunneled cuffed permanent catheters (TCCs) as definitive vascular access were successfully placed in the 5 patients on chronic HD. Warfarin therapy was started to avoid TCCs thrombosis. The median survival of TCCs was 9.5 [3-48] months. All the patients had a history of deep venous thrombosis (DVT). Conclusion To our knowledge this is the first case series of multiple AVF failures in patients with hyperoxaluria. In our experience TCCs show longer survival then AVF in this group of patients, even if it could not be excluded the role of warfarin in favoring this result. Even though a link between hyperoxaluria and thrombosis is well established, the exact underlying mechanism is still uncleared. The role of PD as dialysis technique of “first choice” should be enhanced also when residual renal function is abolished. In ESRD patients with urolithiasis, diagnosis of Hyperoxaluria should be ruled out before AVF placement.