[Superior Cava Vein stenosis in a hemodialysis patient with long-term central venous catheter and vascular graft: a case report].

Recently, the use of central venous catheters (CVC) as a vascular access in patients undergoing hemodialysis is significantly increased, mainly because of the aging of this population and the presence of several comorbidities. However, the implantation and the long stay of CVC are associated with many complications. Among them, central venous stenosis represents one of the most common problems that, if not properly diagnosed, could lead to vascular thrombosis and consequent vascular access malfunction. Here, we report a case of a 38-year-old patient, who underwent hemodialysis firstly by a CVC long-term into right jugular vein and then by a prosthetic fistula in the ipsilateral limb. The patient presented many episodes of vascular access thrombosis that required endovascular interventions. The ultrasound screening and CT-angiography revealed an asymptomatic stenosis of the superior cava vein, which treatment with the implantation of vascular stent resulted in an initial improvement of vascular access performance. However, in the following months, a restenosis was observed that required new interventions to reestablish a satisfactory vascular access function. This case highlights that patients on hemodialysis should undergo proper clinical and instrumental follow-up in order to prevent or early recognize vascular access complications.

[Nonconvulsive status epilepticus due to Fentanyl intoxication in hemodialysed patients: two case reports and review of the literature]. / Stato di male epilettico generalizzato non convulsivo secondario a intossicazione da Fentanyl in pazienti emodializzati: analisi di due casi clinici e revisione della letteratura.

The management of the pain therapy (ischemic pain, neoplastic pain) in hemodialysis patients has become a frequent challenge in the last years. These patients often require the prescription of major analgesic drugs such as Opioids like Fentanyl, in order to control the pain. It is necessary to pay attention to the correct dosage and to the half life of these drugs, that results prolonged in the chronic renal insufficiency. The main side effect of opioids is respiratory depression which is well known, however, up to date, there is a lack of reports about other less frequent side effects, such as epilepsy or status epilepticus, in the literature. We report two cases of chronic hemodialysed patients who developed a generalized nonconvulsive status epilepticus secondary to Fentanyl intoxication administered for the pain therapy. These cases required a synergic team management with involvement of the nephrologist, the neurologist and the intensivist. The generalized non convulsive status epilepticus could be an important and serious side effect of Fentanyl in hemodialysis patients and it is therefore necessary a close monitoring of the pain therapy in these subjects.

The nephrologist's anticoagulation treatment patterns/regimens in chronic hemodialysis patients with atrial fibrillation.

BACKGROUND: The prevalence of atrial fibrillation (AF) is high in hemodialysis (HD) patients. It was suggested that oral anticoagulant therapy (OAT), the choice treatment for reducing the thromboembolic risk in AF patients, increases the incidence of both ischemic and hemorrhagic strokes in the HD population. Moreover, the therapy-related bleeding risk is particularly high in these patients. For these reasons there is no agreement on the use of OAT in HD patients with AF. The aim of this study was to evaluate the criteria adopted by nephrologists in prescribing OAT in HD patients with AF. METHODS: All the patients presenting AF (paroxysmal, persistent or permanent) at 31/10/2010 (n = 290) were recruited from 1529 HD patients from ten Italian HD centres. To detect factors related to OAT administration the main clinical features, CHADS2 and HASBLED scores were evaluated in logistic regression models. RESULTS: The presence of permanent AF (OR = 4.28, p < 0.0001) was the only clinical factor directly associated to OAT administration, while previous bleedings (OR = 0.35, p = 0.004) were inversely related. The CHADS2 score was not associated with OAT prescription (OR = 0.85, p = 0.08), while an inverse relation was found with the hemorrhagic risk score (OR = 0.74, p = 0.03). CONCLUSION: A high AF prevalence was observed in our HD population, but less than 50 % of these patients received OAT. Patients with permanent AF were more frequently treated with warfarin, while OAT administration was uncommon in those with previous bleedings. The thromboembolic risk score was not associated with warfarin prescription, while there was an inverse relation with the hemorrhagic risk score.

[Surveillance of arteriovenous fistula: new answers to an old problem]. / Sorveglianza della fistola arterovenosa: nuove risposte a un vecchio problema.

Arteriovenous fistula (AVF) surveillance is pivotal to early detection of stenosis, in order to avoid subsequent thrombosis. Access flow measurement is the method recommended by the available guidelines. With respect to grafts, in native AVF the best thresholds of access flow intervention, optimal timing of monitoring and cost-effectiveness are still debated. In fact, monthly measurement of access flow is difficult to obtain in most modern hemodialysis units. Moreover, in native AVF it is not always possible to perform the gold-standard surveillance methods. Finally, clinical evaluation is not enough to identify the small number of patients at risk of stenosis. The QB stress test (QBST) is a new and simple screening test that was created to identify inflow stenosis and thereby malfunctioning AVF. QBST shows a good correlation with access flow measurements obtained by the ultrasound dilution technique. Moreover, the test can be performed in every type of native AVF. Patients with a positive QBST result had a lower access flow than patients with a negative QBST result (433+-203 vs 1168+-681 mL/min, p<0.0001). The positive predictive value for inflow stenosis was 76.3%. During a 22-month followup, we were able to achieve a low thrombosis rate (1.5 instances of thrombosis per 100 patient-years). In conclusion, adding QBST to the clinical evaluation could offer a new solution for the long-standing AVF surveillance problem.

The middle-arm fistula as a valuable surgical approach in patients with end-stage renal disease.

BACKGROUND: American and European guidelines recommend the distal radial-cephalic fistula (dRCF) as the first and best hemodialysis access in patients with end-stage renal disease (ESRD). However, this kind of arteriovenous fistula (AVF) shows a limited primary unassisted patency and frequently needs surgical revisions or angiographic procedures, or both. When dRCF is not feasible, guidelines suggest a proximal brachiocephalic AVF. The middle-arm fistula (MAF), or autogenous forearm radial-median direct access, has been suggested as a possible alternative approach. This study evaluated MAF primary unassisted patency, the most frequent causes of MAF failure, and the possible related factors. METHODS: Data on patients with a MAF placed from January 1991 until June 2008 were retrospectively collected. The probability of MAF failure overall and by the main subgroups was estimated according to Kaplan-Meier with Greenwood standard error (SE). Comparison of failure among different subgroups was performed using the log rank test in univariate analyses. The Cox regression model was used to investigate factors that independently affected the overall hazard of failure and cause-specific hazard of thrombosis. RESULTS: At the end of follow-up, 14.0% of MAF failed (11.6% thrombosis, 1.7% stenosis, 0.7% failed maturation), and 44.2% of MAF were still working. Cumulative probability of MAF unassisted primary patency after 4 years from the creation was 79%. Univariate analyses highlighted that women (P = .019), underweight patients (P = .010), and MAF implantation after starting hemodialysis (P < .001) had a higher risk of MAF failure for any cause than men, normal and overweight patients, and MAF implanted before starting hemodialysis. Results of the Cox multivariate analysis for overall MAF failure confirmed that only MAF implantation before starting hemodialysis is a protective factor against any failure (P = .003), whereas female gender (P = .016) was associated with an increase of the thrombosis hazard ratio to 2.04 (95% confidence interval, 1.14-3.63). CONCLUSION: Our data demonstrate that MAF has a good unassisted primary patency and suggest that this kind of AVF could be a valuable alternative surgical approach when dRCF is not feasible in ESRD patients.

Alterations of atrial electrophysiology induced by electrolyte variations: combined computational and P-wave analysis.

AIMS: Haemodialysis (HD) therapy represents a unique model to test in vivo, in humans, the effects of changes in plasma ionic concentrations. Episodes of paroxysmal atrial fibrillation (AF) often occur during the treatment. We investigated the effects of HD-induced electrolyte variations on atrial electrophysiology by analysing ECG P-wave duration (PWd), which reflects atrial conduction velocity (CV), and simulated atrial action potential (AP). METHODS AND RESULTS: In 20 end-stage renal disease patients PWd (signal-averaged ECG), heart rate (HR), blood pressure, Na(+), K(+), Ca(2+), and Mg(2+) plasma concentrations were measured before and after HD session. The Courtemanche computational model of human atrial myocyte was used to simulate the atrial AP. AP upstroke duration (AP(ud)), AP duration and atrial cell effective refractory period (ERP) were computed. Extracellular electrolyte concentrations and HR were imposed to the average values measured in vivo. HD decreased K(+) (from 4.9 +/- 0.5 to 3.9 +/- 0.4 mmol/L, P < 0.001) and Mg(2+) (0.92 +/- 0.08 to 0.86 +/- 0.05 mmol/L, P < 0.05), and increased Na(+) (139.8 +/- 3.4 to 141.6 +/- 3.1 mmol/L, P < 0.05) and Ca(2+) (1.18 +/- 0.09 to 1.30 +/- 0.07 mmol/L, P < 0.001) plasma concentrations. PWd systematically increased in all the patients after HD (131 +/- 11 to 140 +/- 12 ms, P < 0.001), indicating an intra-atrial conduction slowing. PWd increments were inversely correlated with K(+) variations (R = 0.73, P < 0.01). Model-based analysis indicated an AP(ud) increase (from 2.58 to 2.94 ms) after HD, coherent with experimental observations on PWd, and a reduction of ERP by 12 ms. CONCLUSION: Changes of plasma ionic concentrations may lead to modifications of atrial electrophysiology that can favour AF onset, namely a decrease of atrial CV and a decrease of atrial ERP.

Validation of QB stress test as a useful tool in the detection of native arteriovenous fistula stenosis: results after 22 months of follow-up.

BACKGROUND: Access flow (QA) surveillance is the best method recommended for early stenosis detection, but in native arteriovenous fistula (AVF), the literature is conflicting about the real need for monthly monitoring of QA, as suggested by the K-DOQI Guidelines. METHODS: From 1 January 2006 to 31 October 2007 (mean 18.0 +/- 4.9 months), we prospectively followed up 224 patients with monthly AVF monitoring by means of clinical examination and QB stress test (QBST). Suspected malfunctioning AVFs were referred to ultrasound dilution technique (UDT) and imaging techniques (Doppler ultrasonography, angiography), with eventually further percutaneous angioplasty (PTA) or surgical revision. RESULTS: We observed a good correlation between QBST and QA measurement obtained by the UDT. Patients with positive QBST had a lower QA than negative QBST subjects (433 +/- 203 vs 1168 +/- 681 ml/min, P < 0.0001). Fifty-four out of 224 (24%) patients were selected for possibly malfunctioning AVF. We found no stenosis in 13 out of 54 (24%) patients, inflow stenosis in 29 out of 54 (54%) patients and outflow stenosis in 12 out of 54 (22%) patients. The QBST positive predictive value for inflow stenosis was 76.3%. The interventional radiologist performed 38 PTA procedures in 33 patients (11 PTA per 100 patient-years) and we surgically created 13 new AVF (3.7 per 100 patient-years). Only five thrombosis episodes occurred in five patients during the follow-up (1.5 thromboses per 100 patient-years). CONCLUSIONS: QBST is a simple, low-cost, not time-consuming test, able to select, together with clinical evaluation, malfunctioning AVF with stenosis located specifically in the inflow tract. Our follow-up data demonstrated that it is possible to achieve a low AVF thrombosis rate by adding QBST in an AVF monitoring program, thus reducing the surveillance burden.

Sudden death and associated factors in a historical cohort of chronic haemodialysis patients.

BACKGROUND: In haemodialysis patients, deaths due to cardiovascular causes constitute a large proportion of total mortality and sudden cardiac deaths account for approximately 22% of all deaths. The aim of this study was to evaluate the incidence of sudden cardiac death and associated risk factors in a cohort of haemodialysis patients. METHODS AND RESULTS: The 3-year cumulative incidence of death in a cohort of 476 patients on chronic haemodialysis treatment was 34.3% (SE 2.3). Sudden death had a 6.9% (SE 1.2) cumulative incidence, with 32 events representing 19.2% of all deaths, while cardiovascular not sudden death and noncardiovascular death accounted for a 3-year cumulative incidence of 7.3% (SE 1.2) and 20.1% (SE 1.9), respectively. According to Cox multivariate analysis, significant risk factors for sudden death were the presence of atrial fibrillation, diabetes mellitus, predialytic hyperkalaemia, haemodialysis mode and C-reactive protein level, which were associated with a 2.9 (CI(95%) 1.3-6.4), 3.0 (CI(95%) 1.3-7.2), 2.7 (CI(95%) 1.3-5.8), 4.5 (CI(95%) 1.3-15.5) and 3.3 (CI(95%) 1.2-8.8)-fold increase in the risk of sudden death, respectively. Sudden death was significantly more frequent during the first 24 h of the first short interdialytic interval and during the last 24 h of the long interval, i.e. immediately before and immediately after the first weekly haemodialysis session (P = 0.02). CONCLUSIONS: Our data show that the incidence of sudden death in haemodialysis patients is high and that atrial fibrillation, diabetes, hyperkalaemia, haemodialysis mode and C-reactive protein play an important role in developing fatal arrhythmia. Further studies will be necessary to define which interventions could be helpful in reducing this cause of mortality.

Atrial fibrillation and morbidity and mortality in a cohort of long-term hemodialysis patients.

BACKGROUND: Atrial fibrillation is associated with increased mortality and hospitalization in the general population. Data about mortality, morbidity, and hospitalization in hemodialysis patients with atrial fibrillation are limited. SETTING & PARTICIPANTS: All patients (n = 476) in 5 dialysis centers in Lombardia, Italy, as of June 2003 were enrolled and followed up until June 2006 (median age, 69 years; median hemodialysis duration, 45.2 months; and median follow-up, 36 months). 127 patients had atrial fibrillation at enrollment. PREDICTORS & OUTCOME: A Cox model was used to relate: (1) atrial fibrillation, age, hemodialysis therapy duration, and comorbid conditions to all-cause and cardiovascular mortality; (2) angiotensin-converting enzyme (ACE)-inhibitor treatment and comorbid conditions to new onset of atrial fibrillation; and (3) atrial fibrillation and comorbid conditions on hospitalization. RESULTS: There were 167 deaths (39.5% from cardiovascular disease). In multivariable models, atrial fibrillation was independently associated with increased mortality (hazard ratio [HR], 1.65; 95% confidence interval [CI], 1.18 to 2.31). This was more notable for cardiovascular (HR, 2.15; 95% CI, 1.27 to 3.64) than noncardiovascular mortality (HR, 1.39; 95% CI, 0.89 to 2.15). New-onset atrial fibrillation occurred in 35 of 349 individuals (4.1 events/100 person-years); the risk of incident atrial fibrillation was lower in those using ACE-inhibitor therapy (HR, 0.29; 95% CI, 0.10 to 0.82) and higher in those with left ventricular hypertrophy (HR, 2.55; 95% CI, 1.04 to 6.26). There were 539 hospitalizations during 3 years, with 114 hospitalizations in 162 patients with atrial fibrillation and 155 hospitalizations in 314 patients without atrial fibrillation (HR, 1.54; 95% CI, 1.18 to 2.01). Rates of stroke did not significantly differ by atrial fibrillation status (P = 0.4). LIMITATIONS: Because of the observational nature of this study, results for treatment need confirmation in future trials. CONCLUSIONS: Atrial fibrillation is associated with greater total and cardiovascular mortality. Patients with atrial fibrillation were hospitalized more frequently than patients without atrial fibrillation. ACE inhibitors may decrease the risk of new-onset atrial fibrillation.

Prevalence of atrial fibrillation and associated factors in a population of long-term hemodialysis patients.

BACKGROUND: Hemodialysis (HD) is associated with cardiovascular structural modifications; moreover, during HD, rapid electrolytic changes occur. Both factors may favor the onset of atrial fibrillation. METHODS: To define the prevalence of atrial fibrillation and identify associated factors, 488 patients on long-term HD therapy (age, 66.6 +/- 13.4 years; men, 58.0%; duration of HD, 76.5 +/- 84.3 months) were studied. RESULTS: Atrial fibrillation was reported in 27.0% of patients; paroxysmal in 3.5%, persistent in 9.6%, and permanent in 13.9%. Clinical and echocardiographic variables were considered: patients with atrial fibrillation were older (71.8 +/- 9.3 versus 64.7 +/- 14.2 years; P < 0.01), and its prevalence increased with age. Patients with arrhythmia had a longer duration of dialysis therapy (93.2 +/- 100.5 versus 70.2 +/- 76.7 months; P = 0.02). Atrial fibrillation was associated significantly with ischemic heart disease (P < 0.01), dilated cardiomyopathy (P < 0.01), acute pulmonary edema (P < 0.05), valvular disease (P < 0.05), cerebrovascular accidents (P < 0.05), and predialytic hyperkalemia (P < 0.05). Patients with atrial fibrillation more frequently showed left atrial dilatation (59.8% versus 34.5%; P < 0.0001), and in these subjects, left ventricular ejection fraction was significantly lower (53.9% versus 57.4%; P = 0.029). No association was found between arrhythmia and hypertension or diabetes. Multivariate analysis confirmed that patient age (P < 0.001), duration of HD therapy (P = 0.001), and left atrial dilatation (P < 0.001) were associated with atrial fibrillation. CONCLUSION: Atrial fibrillation is much more frequent in HD patients than in the general population; age, duration of HD history, presence of some heart diseases, and left atrial dilatation are associated with the arrhythmia.