Vascular access for hemodialysis in Italy: What a national survey reveals.

BACKGROUND: Since in Italy there are no official data on vascular access (VA) for hemodialysis the Vascular Access Project Group (VAPG) of the Italian Society of Nephrology (SIN) designed a national survey. METHODS: A 35-question survey was designed and sent it to the Italian facilities through the SIN website. The basic questions were the prevalence, the location, and the surveillance of VA, the bedside use of ultrasound, the use of fluoroscopy for central venous catheter (CVC) placement, and of buttonhole technique, the role of nephrologist in the access creation. RESULT: The questionnaire was completed in June 2022 by 161 facilities. The survey registered 15,499 patients, approximately one-third of the Italian dialysis population. The prevalence of arteriovenous fistula (AVF), arteriovenous Graft (AVG), and CVC were 61.8%, 3.7%, and 34.5% respectively. The AVF location was 50% in distal forearm, 20% in meanproximal forearm, 30% in upper arm. For AVF creation, nephrologists were involved in 72% of facilities while for CVC placement in 62%. As regards VA monitoring, 21% of the facilities did not have a surveillance protocol; 60% did not register AVF thrombosis and 53% did not register CVC infections. Most of facilities use the fluoroscope during CVC placement, 37% when needed, and 22% never. Ultrasound-guided puncture of complex AVFs was used by 80% of facilities. Buttonhole puncture was used in 5% of patients. CONCLUSIONS: Some considerations emerge from the survey data: (1) The increasing CVC prevalence compared to DOPPS 5 study. (2) The low rate of AVG prevalence. (3) The nephrologist is the operator in many VA procedures. (4) The fluoroscopy for CVC placement and the US-guide puncture of the complex AVF are widely used in most facilities. (5) The practice of the buttonhole is not widespread. (6) When the operator is the nephrologist more distal fistulas are performed.

Poor neutralization and rapid decay of antibodies to SARS-CoV-2 variants in vaccinated dialysis patients.

Patients on dialysis are at risk of severe course of SARS-CoV-2 infection. Understanding the neutralizing activity and coverage of SARS-CoV-2 variants of vaccine-elicited antibodies is required to guide prophylactic and therapeutic COVID-19 interventions in this frail population. By analyzing plasma samples from 130 hemodialysis and 13 peritoneal dialysis patients after two doses of BNT162b2 or mRNA-1273 vaccines, we found that 35% of the patients had low-level or undetectable IgG antibodies to SARS-CoV-2 Spike (S). Neutralizing antibodies against the vaccine-matched SARS-CoV-2 and Delta variant were low or undetectable in 49% and 77% of patients, respectively, and were further reduced against other emerging variants. The fraction of non-responding patients was higher in SARS-CoV-2-naïve hemodialysis patients immunized with BNT162b2 (66%) than those immunized with mRNA-1273 (23%). The reduced neutralizing activity correlated with low antibody avidity. Patients followed up to 7 months after vaccination showed a rapid decay of the antibody response with an average 21- and 10-fold reduction of neutralizing antibodies to vaccine-matched SARS-CoV-2 and Delta variant, which increased the fraction of non-responders to 84% and 90%, respectively. These data indicate that dialysis patients should be prioritized for additional vaccination boosts. Nevertheless, their antibody response to SARS-CoV-2 must be continuously monitored to adopt the best prophylactic and therapeutic strategy.

Effect of oral anticoagulant therapy on mortality in end-stage renal disease patients with atrial fibrillation: a prospective study.

BACKGROUND: The aim of this study was to evaluate, in a cohort of haemodialysis patients with atrial fibrillation (AF), the relationship between oral anticoagulant therapy (OAT) and mortality, thromboembolic events and haemorrhage. METHODS: Two hundred and ninety patients with AF were prospectively followed for 4 years. Warfarin and antiplatelet intake, age, dialytic age, comorbidities, CHA2DS2-VASc and HAS-BLED scores were considered as predictors of risk of death, thromboembolism and bleeding events. In patients taking OAT, the international normalized ratio (INR) was assessed and the percentage time in the target therapeutic range (TTR) was calculated. RESULTS: At recruitment, 134/290 patients were taking warfarin. During follow-up there were 170 deaths, 28 thromboembolic events and 95 bleedings. After balancing for treatment propensity, intention-to-treat analysis on OAT intake at recruitment did not show differences in total mortality, thromboembolic events and bleedings, while the as-treated analysis, accounting for treatment switch, showed that patients taking OAT at recruitment had a significantly lower mortality than those not taking it [hazard ratio, HR 0.53 (95% confidence interval 0.28-0.90), p = 0.04], with a decrease of thromboembolic events [HR 0.36 (0.13-1.05), p = 0.06], and an increase of bleedings [HR 1.79 (0.72-4.39), p = 0.20], both non-significant. Among patients taking OAT at recruitment, those continuing to take warfarin had a significant reduction in the risk of total [HR 0.28 (0.14-0.53), p < 0.001] and cardiovascular [HR 0.21 (0.11-0.40), p < 0.001] mortality compared to patients stopping OAT. CONCLUSIONS: In haemodialysis patients with AF, continuously taking warfarin is associated with a reduction of the risk of total and cardiovascular mortality.

Warfarin use, mortality, bleeding and stroke in haemodialysis patients with atrial fibrillation.

BACKGROUND: Oral anticoagulation therapy (OAT) is the choice treatment for thromboembolism prevention in atrial fibrillation (AF), although data about OAT use in haemodialysis (HD) patients with AF are contradictory. METHODS: The effect of OAT on the risk of mortality, stroke and bleeding was prospectively evaluated in a population of HD patients with AF. All the patients of 10 HD Italian centres alive on 31 October 2010 with documented AF episode(s) were recruited and followed-up for 2 years. OAT and antiplatelet intake, age, dialytic age, comorbidities and percentage time in the target international normalized ratio (INR) range (target therapeutic range; TTR) were considered as predictors of hazard of death, thromboembolic and bleeding events. RESULTS: At recruitment, 134 patients out of 290 were taking OAT. During the follow-up, 115 patients died (4 strokes, 3 haemorrhagic and 1 thromboembolic). Antiplatelet therapy, but not OAT, was associated with increased mortality (HR 1.71, CI 1.10-2.64, P = 0.02). The estimated survival of patients always taking OAT tended to be higher than that of patients who stopped taking (68.6 versus 49.6%, P = 0.07). OAT was not correlated to a significant decreased risk of thromboembolic events (HR 0.12, CI 0.00-3.59, P = 0.20), while it was associated with an increased risk of bleeding (HR 3.96, CI 1.15-13.68, P = 0.03). Higher TTR was associated with a reduced bleeding risk (HR 0.09, CI 0.01-0.76, P = 0.03), while previous haemorrhagic events were associated with higher haemorrhagic risk (HR 2.17, CI 1.09-4.35, P = 0.03). CONCLUSIONS: In our population of HD patients with AF, the mortality is very high. OAT is not associated with increased mortality, while antiplatelet drugs are. OAT seems, on the contrary, associated with a better survival; however, it does not decrease the incidence of ischaemic stroke, whereas it increases the incidence of bleeding. Bleeding risk is lower in subjects in whom the INR is kept within the therapeutic range.

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.

The peritoneal dialysis catheter.

The results obtained from the positioning and management of the catheter for peritoneal dialysis depend on the techniques used, but also and above all, on the experience of the practitioners. A comparison between practitioners may help to change their convictions, as well as to further improve results, in the interests of patient welfare. This is the aim of these Best Practice Guidelines..

[Ozone therapy: a potential adjunct approach to lower urinary tract infection? A case series report]. / Ozone Therapy: Un potenziale approccio alla infezioni delle basse vie urinarie? A Case Series Report.

Multi-resistant drug bacteria are an emerging health care concern around the world. A decreased resistance to infection as seen in Chronic Kidney Disease (CKD) and kidney transplanted patients as well as some metabolic abnormalities such as hyperglycemia and glycosuria or clinical conditions such as the neurogenic bladder may indeed portend a great risk of recurrent urinary tract infections (UTI). The common and indiscriminate use of antibiotics often provides the patients with only a transient or partial amelioration of the urinary tract discomforts and increases the risk of multi-resistant drug bacteria selection. Thus a great effort is made in order to develop new antibacterial approaches especially in the setting of multi- antibiotic resistant pathogens. We herein report on some promising yet preliminary results of the use of ozone therapy in UTI.

Indications for vascular grafts as hemodialysis access: consensus from experience in Italy.

INTRODUCTION: In Italy, the use of arteriovenous grafts (AVG) is limited (1-5 %) due to different approaches to vascular access (VA) management as compared to other countries, where guidelines (which may not apply to the Italian setting) have been produced. Therefore, the Study Group (GdS) on VA of the Italian Society of Nephrology produced this position paper, providing a list of 8 recommendations built upon current guidelines. METHODS: The most controversial and innovative issues of existing guidelines have been summed up in 12 different statements. We selected 60 Italian dialysis graft experts, nephrologists and vascular surgeons (PP1SIN Study Investigators). They were asked to express their agreement/disagreement on each issue, thus creating a new method to share and exchange information. RESULTS: Most of them agreed (consensus > 90%) on specific criteria set to choose AVG over native AVF (nAVF) and tunnelled venous catheter (tVC) and on the necessary conditions to implant them. They did not fully agree on the use of AVG in obese patients, in patients at risk of developing ischemia, on the priority of AVG as an alternative to brachial-basilic fistula with vein transposition, and in case of a poorly organized setting regarding graft maintenance. Keeping in mind that the nAVF should be preferred whenever is feasible, AVGs are indicated when superficial veins are unavailable or to repair a nAVF (bridge graft). An AVG is an alternative to tVC if the expected patient survival is long enough to guarantee its clinical benefits.

Dipyridamole stress echocardiography in diagnosis and prognosis of hemodialysis patients with asymptomatic coronary disease.

The prevalence of coronary artery disease (CAD) is high in hemodialysis (HD) patients. The aim of the study was to assess the diagnostic and prognostic value of dipyridamole stress echocardiography (DSE) in nondiabetic HD patients without signs or symptoms of CAD. In 51 out of 158 evaluated HD patients (21 females, age 67 [33-85] years, HD duration 38 [9-271] months), resting echocardiography and DSE were performed. Exclusion criteria were known CAD, diabetes mellitus, and pulmonary and oncologic pathologies. Logistic regression analysis was carried out to identify predictors of abnormal DSE response, while Cox regression analysis was performed to determine variables associated with total and cardiovascular mortality, after 43.3 (11-60) months of follow-up. Seven patients (14%) showed a positive response to DSE (DSE+). In 5/7, CAD was documented by angiography: All of them underwent coronary revascularization. DSE+ patients had significantly smaller body mass index than patients with a negative response (DSE-): 21.7 ± 1.9 vs. 25.1 ± 3.4 kg/m(2) (p = 0.018). During follow-up, 16 (31%) patients died. Older age hazard ratio [HR = 1.07; confidence interval (CI) = 1.01-1.12; p = 0.02] and higher plasma phosphate levels (HR = 10.41; CI = 2.30-47.17; p < 0.01) were predictors of total mortality. Male gender (HR = 22.7; CI = 1.45-354.4; p = 0.03), older age (HR = 1.24; CI = 1.03-1.50; p = 0.02), longer HD duration (HR = 1.13; CI = 1.01-1.26; p = 0.04), and positive response to DSE (HR = 5.82; CI = 1.04-32.65; p = 0.04) were associated with cardiovascular mortality. Ten percent of asymptomatic HD patients had significant CAD, but timely diagnosis did not seem to improve their prognosis. Total survival was associated with age and higher levels of plasma phosphate, while male gender, older age, longer HD duration, and DSE+ were predictors of cardiovascular mortality.

[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.

Developing recommendations for vascular access for hemodialysis: Vascular Access Working Group of the Italian Society of Nephrology.

This paper presents an overview of the project carried out by the Vascular Access (VA) Working Group of the Italian Society of Nephrology with the aim of developing 4 position papers at the national level on how to choose, use, and implant the different, possible types of vascular access. The topics of the project are: 1) recommendations on the use of prosthetic arteriovenous fistulas for vascular access in hemodialysis, 2) recommendations on the use of venous catheters for hemodialysis, 3) infections induced by a venous catheter for hemodialysis, and 4) how to create and maintain a vascular access for hemodialysis. This paper also gives an explanation of the difficulties existing in Italy in the implementation of international guidelines, mostly due to significant differences in the procedures for the creation of VA, compared with the countries where most of the literature on the subject has been published. Individual position papers were drafted for each of the different topics. A list of recommendations was produced based on existing guidelines. Then these recommendations were critically reviewed by experts working in Italy, who expressed their opinion on their inclusion in position papers. The working method used to gather the opinions of the various experts is described. The final target is to provide clinicians interested in VA with updated documents on selected topics. Such documents will be updated periodically, and they will present a thorough overview of expert opinions.

[Indications for vascular grafts as dialysis access; consensus from the Italian experience]. / Indicazioni all'uso delle protesi vascolari per l'accesso emodialitico: un'esperienza Italiana basata sul consenso.

In Italy, the use of arteriovenous grafts (AVGs) is limited (1-4%) due to different approaches to vascular access management compared to other countries, where guidelines that may not apply to the Italian setting have been produced. Therefore, the Vascular Access Study Group of the Italian Society of Nephrology produced this position paper, providing a list of 8 recommendations built upon current guidelines. The most controversial and innovative issues of the existing guidelines have been summed up in 12 different topics. We selected 60 Italian dialysis graft experts, nephrologists and vascular surgeons (PP1SIN Study Investigators). They were asked to express their approval or disapproval on each issue, thus creating a new method to share and exchange information. Almost all agreed on specific criteria for the choice of AVG over native arteriovenous fistulas (AVF) and tunneled venous catheters (tVC) and on the necessary conditions to implant them. They did not fully agree on the use of AVG in obese patients and patients at risk of developing ischemia, as an alternative to brachiobasilic fistula with vein transposition, and in case of a poorly organized setting. When AVF is feasible, it should be preferred. AVGs are indicated when superficial veins are unavailable or to repair an AVF (bridge graft). An AVG is an alternative to tVC if the expected patient survival is long enough to allow clinical benefits. The ultimate choice of the graft type is made by the physician in charge of the surgical intervention. Antithrombotic prophylaxis may be justified in some cases.

[Vascular access for hemodialysis: recommendations of the Vascular Access Study Group of the Italian Society of Nephrology]. / Gli accessi vascolari per emodialisi: le raccomandazioni del Gruppo di Studio della Società Italiana di Nefrologia.

The Vascular Access Study Group of the Italian Society of Nephrology has scheduled four national studies regarding the choice, implantation and use of vascular access. Study topics will include 1) utilization of vascular grafts for hemodialysis; 2) indications and use of venous catheters; 3) tunneled central venous catheter infection; 4) organization of the implantation and repair of vascular access. After examining the difficulties in implementing international guidelines on vascular access in Italy and the differences in practice patterns between our and other countries (where the most important studies were published), the Study Group set out to prepare four position papers based on discussion of controversial aspects of the international guidelines by nephrologists and surgeons experienced in the Italian practice. An innovative operative method for verifying the consensus on vascular access practice patterns was used. The final aim was to write a document addressed to vascular access operators (surgeons and nephrologists) based on the consensus of experts on controversial vascular-access- related issues. The project will include yearly updates of the documents.

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.

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.

The middle-arm fistula: A new native arteriovenous vascular access for hemodialysis patients.

Dialysis access procedures and complications are important causes of morbidity and hospitalization for chronic hemodialysis patients. The number of complicated subjects on dialysis is increasing, and creating a successful native arteriovenous fistula for these patients is a challenge. The classic Brescia-Cimino fistula may not be the best first choice for a native vascular access. We describe the surgical technique of middle-arm fistula (MAF) for hemodialysis. A total of 112 surgical procedures were performed on 106 patients with primary unassisted 24- and 48-month patency rates of 93% and 83%, respectively, and a very low incidence of complications. Our approach was found to be a useful method in patients with comorbid factors.

Dynamic QT interval analysis in uraemic patients receiving chronic haemodialysis.

OBJECTIVE: To analyse the duration of the QT interval and its relationship with heart rate changes in patients with uraemia, before and during haemodialysis. METHODS: QT and RR intervals were measured automatically using a dedicated algorithm with 24-h Holter recordings in 29 patients (15 women) receiving chronic haemodialysis. QT corrected for heart rate (QTc) and the slope of QT/RR linear regression were calculated. Arterial blood pressure (ABP) was measured before and during haemodialysis. Plasma concentrations of K+, Mg2+ and Ca2+ were assessed before and after haemodialysis. RESULTS: ABP decreased significantly from baseline (102.7 +/- 11.0 mmHg) during the first (100.6 +/- 8.8 mmHg, P < 0.05), second (95.6 +/- 10.6 mmHg, P < 0.05), and third (94.9 +/- 10.3 mmHg, P < 0.05) hours of haemodialysis. QTc was longer during haemodialysis than during a 4-h period of no dialysis (447 +/- 28 ms compared with 429 +/- 22 ms, P < 0.001), and increased progressively during haemodialysis, with the greatest value during the last hour of haemodialysis (454 +/- 32 ms compared with 426 +/- 22 ms, P < 0.001). QT/RR slopes and correlation coefficients were lower during haemodialysis than during the period of no dialysis (0.13 +/- 0.08 compared with 0.20 +/- 0.07, P < 0.001 and 0.48 +/- 0.30 compared with 0.81 +/- 0.20, respectively; P < 0.001), suggesting a reduced ability to adapt the QT interval in response to changes in heart rate. The effects of haemodialysis on QT interval and the QT/RR relationship were greater in women than in men. QTc variations during dialysis were not correlated with changes in ABP, but were inversely related to changes in Ca2+ concentration (r2 = 0.35; P = 0.001). CONCLUSIONS: In patients with uraemia, the haemodialysis session induces a progressive increase in QT interval and modifies its relationship with heart rate. These effects may predispose some individuals to ventricular arrhythmias at the end of and immediately after the haemodialysis session.

Influence of left ventricular mass, uremia and hypertension on vagal tachycardic reserve.

BACKGROUND: Left ventricular (LV) hypertrophy, arterial hypertension and end-stage renal disease (ESRD) are associated with deranged cardiac parasympathetic regulation and increased cardiovascular risk. These conditions often co-exist but little is known about the relative contribution of LV mass, arterial blood pressure and ESRD to impaired cardiac vagal tone. We evaluated the vagal tachycardic reserve (VTR) in subjects with normal renal function (age 58.4 +/- 6.6 years, n = 19) and in patients under chronic hemodialysis (HD) (age 62.6 +/- 13.2 years, n = 30) having wide ranges of LV mass and blood pressure. METHODS: VTR was estimated from the tachycardic response to atropine (15 microg/kg intravenously) administered during a dipyridamole-atropine stress-echo test performed as part of the diagnostic work-up for identification of inducible myocardial ischemia. LV hypertrophy (defined as LV mass index > 125 g/m2 in both genders) was present in 20 HD patients and in nine control patients. Only patients free of inducible myocardial ischemia were included in the study. RESULTS: The atropine-mediated tachycardia was: (i) significantly smaller in HD patients than in control patients (34.7 +/- 7.6 versus 60.8 +/- 10.5 beats/min, P < 0.01); (ii) independently and inversely related to LV mass (multiple regression; partial coefficients, -0.139 in HD patients and -0.382 in controls, both P < 0.01) and to mean blood pressure (-0.171 in HD patients and -0.268 in controls, both P < 0.01). CONCLUSIONS: LV mass is the strongest (inverse) determinant of VTR. Blood pressure as well as the patient's renal status are also independent correlates of VTR, and the concomitance of LV hypertrophy and ESRD exacerbates the impairment of VTR.