MO025TREATMENT WITH TOLVAPTAN IN ADPKD PATIENTS: RESULTS FROM AN OBSERVATIONAL, MULTICENTRIC STUDY

Background and Aims

In recent years, treatment of ADPKD (Autosomal Dominant Polycystic Kidney of the Adult) has been based on the antisecretive and antiproliferative effect of several drugs. Tolvaptan, a vasopressin receptor antagonist, has been shown to slow disease progression in the face of side effects such as aquaresis and liver damage. Currently, the drug's reimbursability is allowed in patients aged up to 55 years, CKD 2-4 (GFR ≥ 25 ml/min) with evidence of rapid disease progression.

Method

We report the experience with Tolvaptan in 62 patients with ADPKD who were recruited from 11 Nephrology Units in Lazio (Italy).

Baseline characteristics of patients are reported in Table 1.

Renal volume was evaluated by MRI (26 patients), CT scan (3 patients), or ultrasonography (28 patients).

Rapid progression’s criteria were the following: Mayo Clinic classification, PRO-PKD score and the annual loss of GFR. Mean duration of Tolvaptan’s treatment was 522 days (range 56-867).

The Tolvaptan dosage used at the beginning of therapy was 60 mg/day in 95% of patients; at the end of follow-up, 37% were still taking 60 mg/day, while 38.7% were taking 90 mg/day and 16.1% were taking 120 mg/day.

Results

Median diuresis was 5-6 liters over 24 hours. A mean reduction in GFR of 12.5% (which was maintained for the next 12 months) was observed after initiation of therapy as a likely effect of tubulo-glomerular feedback.

Monthly blood tests were performed to monitor side effects (hyper/hyponatremia, increased bilirubin and/or transaminases, etc.).

Therapy was withdrawn by 2 patients (3.2%) due to aquaresis, while it was discontinued in 3 patients (4.8%) according to clinicians’ decision due to hepatic damage (3-fold increase in transaminases and/or bilirubin normal values). No significant alteration in natremia was observed in any patient. An increase in CK was observed in one patient, leading to momentary discontinuation of therapy. One patient withdraw therapy because of CKD’s progression to stage 5 after 2 years of therapy.

Conclusion

Results of this observational study show that Tolvaptan therapy was well tolerated and the incidence of liver damage was superimposed on that described in the literature.

It will be necessary to continue clinical observation over the time and apply Tolvaptan’s therapy to a larger population in order to assess its effects on disease progression.

Hemodynamic impact of VASQ device in vascular access creation

BACKGROUND

Native arteriovenous fistula is the preferred vascular access in term of functionality, efficiency and complication rate. Nevertheless, research continues to seek strategies to reduce the risk of neointimal hyperplasia and hemodynamic modification. The aim of the study was to evaluate the impact on hemodynamic of the VasQ device in arteriovenous fistulae creation.

METHODS

The analysis included patients who underwent to fistula creation with or without implantation of the VasQ device between May and September 2019. The hemodynamic parameters were evaluated pre-operatively and at a follow-up of 1, 3, 6 months. The patency and complication rate were evaluated.

RESULTS

Fifteen VasQ devices were implanted during 30 arteriovenous fistula surgery. The baseline patients features were similar between groups (VasQ treated/control). At baseline, preoperative arterial flow was similar; radial artery diameter at surgical site was 3.4 ± 0.8 mm in treated and 2.8 ± 0.5 mm in the control group. The mean arterial flow at 1 month was 480 ± 210 mL/min in treated and 561 ± 27 mL/min in the control group. At 3 months the mean arterial flow in treated was 645 ± 143 mL/min versus 824 ± 211 mL/min (p = 0.02) in the control group; at 6 months the arterial flow was 714 ± 146 mL/min versus 810 ± 194 mL/min (p = 0.05) in control group. The cardiac output flow at 6 months in the treated group was 4458 ± 928 mL/min versus 5599 ± 1355 mL/min (p = 0.05) in the control group. At 6 months the primary patency was 73% and 80% and the secondary patency 80% and 86% in treated compared to the control group, respectively. No VASQ device complications were recorded.

CONCLUSION

The analysis of these data suggested that using VasQ device could be protective against the hemodynamic modification that occur during arteriovenous fistulae creation.

Cardionephrology: A Widespread Discipline for 21th Century Medical Students and Young Nephrology Residents

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[Neprilysin inhibition and chronic kidney disease]

Patients with chronic kidney disease (CKD) have a higher incidence of cardiovascular (acute and chronic) events, which in turn have an increased risk of progression to end-stage renal disease (ESRD) Inhibition of neprilysin, in addition to offering a new therapeutic target in patients with heart failure, could represent a potential improvement strategy in cardiovascular and renal outcome of patients with CKD. Inhibition of neprilysin by inhibiting the breakdown of natriuretic peptides, increases their bioavailability resulting in an increase in diuresis and sodium excretion and, in addition to exerting an inhibition of the renin-angiotensin-aldosterone (RAAS) system. Inhibition of RAAS, in turn, generates a series of counter-regulations that can balance the adverse effects present in CKD and heart failure (HF). The idea of blocking neprilysin is not very recent, but the first drugs used as inhibitors had an inadmissible incidence of angioedema. Among the latest generation molecules that can perform a specific inhibitory action on the neprilysin receptor and, at the same time, on the angiotensin II receptor thanks to the association with valsartan there is the LCZ696 (sacubitril / valsartan). This drug has shown promising benefits both in the treatment arterial hypertension and heart failure. It is hoped that equally positive effects may occur in CKD patients, particularly those with macroproteinuria.

Sudden cardiac death and chronic kidney disease: From pathophysiology to treatment strategies

Chronic kidney disease (CKD) patients demonstrate higher rates of cardiovascular mortality and morbidity; and increased incidence of sudden cardiac death (SCD) with declining kidney failure. Coronary artery disease (CAD) associated risk factors are the major determinants of SCD in the general population. However, current evidence suggests that in CKD patients, traditional cardiovascular risk factors may play a lesser role. Complex relationships between CKD-specific risk factors, structural heart disease, and ventricular arrhythmias (VA) contribute to the high risk of SCD. In dialysis patients, the occurrence of VA and SCD could be exacerbated by electrolyte shifts, divalent ion abnormalities, sympathetic overactivity, inflammation and iron toxicity. As outcomes in CKD patients after cardiac arrest are poor, primary and secondary prevention of SCD and cardiac arrest could reduce cardiovascular mortality in patients with CKD.

[Chronic kidney disease and sudden death]

Cardiovascular disease represents the major cause of death in chronic kidney disease patients accounting for about 43% of all mortality causes among hemodialysis patients. Sudden cardiac death (SCD) is one of the most frequent and dangerous clinical syndrome occurring in end stage renal disease (ESRD) patients. Hemodialysis patients present a great number of non traditional risk factors for cardiovascular disease such as left ventricular hypertrophy, coronary artery disease, rapid electrolyte shifts, QT dispersion, sympathetic hyperactivity and hyperphosphatemia. The aim of the following review is to summarize epidemiological aspects and pathophysiological pathways of SCD in CKD patients, defining prevention and treatment guidelines.

[Assessment of right ventricular function in patients with chronic kidney disease stage IV NKF]

Cardiovascular diseases are accountable for almost 50% of over-all mortality rates in chronic kidney disease (CKD) patients, especially in those who undergo hemo-dialysis or peritoneal dialysis.Hemodialysis patients present higher rates of pulmonary hypertension (PH), an independent risk factor for cardiovascular mortality among this patient population, due in part to the presence and hemodynamic effects of vascular access (both artero-venous fistula and central venous catheter). Echocardiographic TAPSE (tricuspid annular plane systolic excursion) index represents a helpful tool for investigation of right ventricular function together with PAPs (systolic pulmonary artery pressure) evaluation.The following study protocol, introduced by the Cardionephrology Study Group of the Italian Society of Nephrology, aims to evaluate the incidence of right ventricular dysfunction and PH in CKD patients. This is a multicentric, case- control study which includes two arms, each comprising 200 patients, and which will last 24-36 months.Glomerular filtration rates (GFR) are calculated using the eGFR EPI equation, while echocardiographic evaluation includes atrial and ventricular dimension and area, left ventricular systolic function (ejection fraction), diastolic function, TAPSE index measurement and PAPs evaluation.

[Pathophysiology and diagnosis of cardio-renal syndrome: actual picture and future prospectives]

The cardiorenal syndrome (CRS) indicates how close the relationship is between heart and kidney during failure of these organs. At present, the classification of the syndrome includes five types of CRS: types I and II which are strictly related to initial heart failure (both acute and chronic), types III and IV which include initial kidney failure, and type V which includes several systemic diseases. Many pathophysiological pathways have been described illustrating how heart and kidney disease are involved in clinical conditions. The diagnosis of CRS is based on both blood tests and ultrasound imaging. Several biomarkers indicating levels of heart and kidney function have emerged over the last few decades which can be used to predict kidney failure in patients with acute or chronic heart disease. Kidney injury biomarkers have also to be tested, especially those indicating glomerular and tubular damage. Renal ultrasound and trans-thoracic echocardiography can provide further information on heart and kidney failure in patients with cardio-renal syndrome at any stage.

Pulmonary Hypertension and Right Heart Failure in Chronic Kidney Disease: New Challenge for 21st-Century Cardionephrologists

Pulmonary hypertension is defined as an increased systolic pulmonary pressure of >30 mm Hg, and it shows a 40% prevalence in hemodialysis patients due to vascular access (both central venous catheter and arteriovenous fistula). Secondary pulmonary hypertension in chronic kidney disease patients is strictly related to pulmonary circulation impairment together with chronic volume overload and increased levels of cytokines and growth factors, such as FGF, PDGF, and TGF-β, leading to fibrosis. Endothelial dysfunction, together with lower activation of NOS, increased levels of serum endothelin and fibrin storages, involves an extensive growth of endothelial cells leading to complete obliteration of pulmonary vessels. Pulmonary hypertension has no pathognomonic and distinctive symptoms and signs; standard transthoracic echocardiography allows easy assessment of compliance of the right heart chambers. The therapeutic approach is based on traditional drugs such as digitalis-derived drugs, vasodilatory agents (calcium channel blockers), and oral anticoagulants. New pharmacological agents are under investigation, such as prostaglandin analogues, endothelin receptor blockers, and phosphodiesterase-5 inhibitors.

Indication to renal biopsy in DM2 patients: potential role of intrarenal resistive index

Diagnosis of diabetic nephropathy is generally based, rather than on histological confirmation, on clinical criteria (long history of diabetes, presence of proteinuria, diabetic retinopathy or peripheral neuropathy). This clinical approach has perhaps limited utility in DM2 patients, because only 50% of them show microvascular complications in presence of nephropathy. Eco-colour-Doppler sampling of interlobular renal arteries and determination of their resistance indices (RI), was proposed in the differential diagnosis of numerous nephropathies. Aim of this study was to evaluate whether RI can be useful in discerning non-diabetic renal disease (NDRD), in order to better define indications to perform renal biopsy among proteinuric DM2 patients. All patients were submitted to: echo-colour-Doppler study of renal vessels; systematic screening for diabetic retinopathy; needle renal biopsy. RI resulted to be significantly higher in diabetic glomerulosclerosis (GSD) group as compared with NDRD group, while no significant difference was found with respect to NDRDs overlapping GSD (overlapping group). The last one showed however median RI significantly higher than isolated NDRD group. Normalized chi square Pearson for the hypothesis that RI can predict GSD resulted 0.73, while it resulted 0.43 for the hypothesis that diabetic retinopathy can predict GSD. Echo-colour-Doppler can significantly contribute, more than the other parameters proposed (nephritic or nephrotic syndrome, hematuria, diabetic retinopathy), to the identification of underlying nephropathy in DM2 subjects. In the light of our experience, it seems that the detection of RI values > 0.72 suggests the diagnosis of GSD or mixed forms, reducing the indications to renal biopsy only in presence of values < 0.72.

[The future of the ultrasonography techniques in nephrology]

Thanks to the wide geographical diffusion, low cost and lack of ionizing radiation, ultrasound is now the most widely used imaging technique in clinical practice, second only to chest radiography. Recent technological innovations and introduction of ultrasound contrast agents, further expanded the fields of application of ultrasound, guarantying for the future to this technique an important role in imaging of the urinary tract. The nephrologist must be able to exploit the potential offered by technological innovations in ultrasound imaging for the study of the kidney. The proper management of equipment, in fact, allows to obtain ultrasound images in gray scale of the highest quality, to optimize the diagnostic accuracy of Doppler techniques and take full advantage of the tools offered by means of ultrasound contrast agents.

[Contrast enhanced ultrasound in renal diseases]

Contrast-enhanced ultrasound (CEUS) is one of the most interesting and promising clinical applications of imaging and ultrasound. Thanks to the absence of ionizing radiation, the lack of nephrotoxicity and low cost it has the potential to become a reference in imaging of the kidney. This review, besides providing a brief description of the proper methodology, presents possible applications of CEUS in nephrology and urology, including renal ischemia, the differential diagnosis of cystic and solid lesions, follow-up of ablative therapies, kidney trauma, kidney transplant, inflammatory diseases, ischemic nephropathy and vesicoureteral reflux.

[Echocardiography in nephrology]

Cardiovascular disease is the main cause of mordibity and mortality in patients with chronic kidney disease (CKD) affected by a series of risk factors (hypertension, anemia, left ventricular hypertrophy, cardiac failure and dyslipidemia). The combined presence of these factors raises the cardiovascular risk in CKD patients considerably compared with that of the general population. Nephrologists can play a role in preventing and treating these risk factors and thereby delaying the development of CKD. In preventing CKD, nephrologists who practice ultrasound techniques should have basic know how of echocardiography so that they can screen CKD patients for early referral to a cardiologist. Echocardiography is a noninvasive ultrasound technique that requires adequately trained doctors to perform it. Nephrologists who practice it need to obtain good training and postgraduate certification of competence in echocardiography. These nephrologists should team up with cardiologists rather than replace them, and at the same time be aware that they possess the basic knowledge to manage cardiovascular disease in CKD patients.

[Microbubbles: current state and future prospects]

Contrast-enhanced ultrasound (CEUS) represents one of the most interesting applications of traditional medical sonography. Ultrasound contrast agents are classified into first- and second-generation agents depending on the gas (nitrogen, perfluorocarbon or sulfur hexafluoride) in the microbubbles. Both generations are characterized by an excellent safety profile, with low hepatic and renal toxicity and rare central nervous system reactions. The respiratory and hepatic elimination of the gases explains the low nephrotoxicity. CEUS has been successfully employed in drug and gene delivery. Indeed, new molecules such as liposomes, micelles and perfluorocarbon nanoparticles have been recently proposed as ultrasound contrast agents. Possible future applications of liposomes are the treatment of hypertension complications (given the possibility to fill them with nitric oxide), the treatment of cerebral disease with xenon, and the treatment of breast and liver cancer with doxorubicin. Micelles have been demonstrated to be effective in cancer treatment as well. Finally, perfluorocarbon nanoparticles can be used in oncological settings and in pancreatic islet transplantation in patients with type I diabetes.

[Ultrasound assessment in renal infections]

Urinary tract infections (UTIs) are a common clinical problem, especially among women. Ultrasound assessment is indicated in case of complicated UTIs, in particular in children, pregnant women and patients with chronic kidney disease. Even though B-mode imaging alone is rarely diagnostic in case of particular kidney infections such as focal and multifocal acute pyelonephritis, Doppler and power-Doppler (PD) techniques are able to increase its sensitivity. Contrast-enhanced ultrasound (CEUS) further improves the signal-to-noise ratio, thus increasing the diagnostic accuracy of ultrasound in case of renal infectious disease. Recent studies performed on kidney transplant recipients have indeed demonstrated the high sensitivity and specificity of CEUS in diagnosing acute pyelonephritis. Moreover, ultrasonography is a useful diagnostic tool in case of kidney abscesses, emphysematous pyelonephritis, early phases of pyonephrosis, and in the evaluation and monitoring of echinococcal cysts. Ultrasound imaging is less specific in diagnosing xanthogranulomatous pyelonephritis, malacoplakia and renal tuberculosis. Finally, several authors recommend routine ultrasound assessment in HIV patients, given the high incidence of renal complications in this population of patients.

[Management of color-Doppler imaging in dialysis patients]

In recent decades, the survival of dialysis patients has gradually increased thanks to the evolution of dialysis techniques and the availability of new drug therapies. These elements have led to an increased incidence of a series of dialysis-related diseases that might compromise the role of dialysis rehabilitation: vascular disease, skeletal muscle disease, infectious disease, cystic kidney disease and cancer. The nephrologist is therefore in charge of a patient group with complex characteristics including the presence of indwelling vascular and/or peritoneal catheters, conditions secondary to chronic renal failure (hyperparathyroidism, anemia, amyloid disease, etc.) and superimposed disorders due to old age (cardiac and respiratory failure, cancer, type 2 diabetes mellitus, etc.). Early clinical and organizational management of such patients is essential in a modern and ''economic'' vision of nephrology. The direct provision of ultrasound services by the nephrologist responds to these requirements. A minimum level of expertise in diagnostic ultrasonography of the urinary tract and dialysis access should be part of the nephrologist's cultural heritage, acquired through theoretical and practical training programs validated by scientific societies, especially for those who choose to specialize in these procedures and become experts in imaging or interventional ultrasonography.

[Vascular complications following kidney transplant: the role of color-Doppler imaging]

The progressive decline in the incidence of graft rejection has made urological, surgical, parenchymal and vascular complications of kidney transplant more frequent. The latter, although accounting for only 5-10% of all post-transplant complications, are a frequent cause of graft loss. Ultrasonography, both in B-mode and with Doppler ultrasound, is an important diagnostic tool in case of clinical conditions which might impair kidney function. Even though ultrasonography is considered fundamental in the diagnosis of parenchymal and surgical complications of the transplanted kidney, its role is not fully understood in case of vascular complications of the graft. The specificity of Doppler ultrasound is very important in case of stenosis of the transplanted renal artery, pseudoaneurysms, arteriovenous fistulas, and thrombosis with complete or partial artery or vein occlusion. Doppler and color determinations present high diagnostic accuracy, which is higher in case of successive measurements performed during the follow-up of the graft. Modern techniques including contrast-enhanced ultrasound increase the diagnostic power of ultrasonography in case of vascular complications of the transplanted kidney, planted kidney.

Echocardiography and right ventricular function in NKF stage III cronic kidney disease: Ultrasound nephrologists' role

TAPSE measurement during echocardiography is a well known measure of right heart systo-diastolic function. Low TAPSE means reduced cranio-caudal excursion of tricuspidal annulus, sign of both reduced ejection fraction and reduced distensibility of right ventricle. It is a good prognostic index for cardiac mortality risk in CHF patients, adding significant prognostic information to NYHA stadiation. Nephrologists do not always fully aware of right ventricular function in their patients affected by chronic renal failure (CRF), even if this datum is probably crucial in vascular access policy. Our study was designed to study right ventricle function and TAPSE on 202 patients affected by moderate chronic renal failure, free from overt pulmonary hypertension. TAPSE, PAPs, right chambers diameters, classical Framingham factors, estimated glomerular filtration rate were recorded. TAPSE was reduced (<23 mm) in 43% of patients enrolled, while dilated right chambers were present in 24%. PAPs exceeded 30 mmHg in 29% of patients. Echocardiographic signs of left ventricular hypertrophy were found in 36% of patients. The ejection fraction was normal in all patients. Statistical analysis showed a significant indirect correlation between TAPSE and PAPs and between TAPSE and tele-diastolic diameters and volumes of the right ventricle, while a direct correlation was observed between TAPSE and Framingham score. TAPSE showed a bimodal distribution, with a subpopulation "low TAPSE - high PAPs", next to a population characterized by normal values ??for both parameters. A reduction in compliance and systolic function of the right heart chambers is quite early and frequent in course of CKD, a fact that the nephrologist should take in due consideration, managing blood volume or planning vascular access for hemodialysis.

[The nephrologist and the role of ultrasound imaging in the diagnosis of cardiorenal syndrome]

The term cardiorenal syndrome (CRS) refers to multiple possible clinicopathological correlations between heart and kidney failure. The most recent classification recognizes five types of CRS: types I and II originate from heart failure (acute and chronic, respectively), type III and IV from kidney failure (again acute and chronic), while type V originates from a range of systemic diseases. Echocardiography and renal ultrasound are important means to arrive at a correct diagnosis. Basic echocardiography (defined by some as "echocardioscopy") allows the assessment of the left and right ventricles (diastolic and systolic function), atrial size, pulmonary circulation markers such as systolic pulmonary arterial pressure (PAPs) and tricuspid annular plane excursion (TAPSE), pericardial effusions, valve dysfunctions, and volume repletion. Renal ultrasound is of help in distinguishing between chronic and acute renal failure (kidney volume, parenchymal thickness, echogenicity) and excluding obstructive kidney disease.

[Use of ECG-EC in the positioning of central venous catheters]

Central venous catheters (CVC) are widely used in clinical practice for the administration of chemotherapy, parental nutrition, hemodynamic monitoring, and hemodialysis. International guidelines have defined the right internal jugular vein as the preferred site of CVC insertion and underline that accurate positioning of the catheter tip is essential to maximize the blood flow and reduce long-term complications. Endocavitary electrocardiography (EC-ECG) improves the accuracy of catheter tip positioning without increasing the placement time by the recognition of typical P wave patterns during catheter insertion:the normally shaped P wave identifies the mid to upper superior vena cava, the widest P wave may be used to place the CVC tip at the superior vena cava-right atrium junction, and biphasic P waves identify the location of the right atrium. Because of its simplicity and safety, EC-ECG should always be considered during CVC placement, especially if other means of verifying correct CVC insertion are not available.

Low-Dose Treatment with Erythropoiesis-Stimulating Agents and Cardiovascular Geometry in Chronic Kidney Disease: Is Darbepoetin-α More Effective than Expected?

INTRODUCTION: Chronic kidney disease (CKD) is a widespread invalidating condition, leading to erythropoietin deficiency and decreased cardiovascular performance. Darbepoetin-α and epoetin-α are extensively used to correct renal anemia. The aim of this study was to evaluate cardiological outcomes in two groups of CKD patients treated with erythropoiesis-stimulating agents (ESA: 20 μg darbepoetin-α weekly vs. 2,000 IU epoetin-α thrice weekly) with an unconventional 1:300 conversion ratio. METHODS: The study was designed as a single center, retrospective, observational study. One hundred stage IV CKD patients were selected. Hemoglobin (Hb), hematocrit, C-reactive protein, pro-brain natriuretic peptide (BNP) and basal echocardiograms were monitored every 3 months. RESULTS: Darbepoetin-α was significantly more effective in increasing Hb levels after 3 (p < 0.0001), 6 (p < 0.0001), 9 (p < 0.01) and 12 months (p < 0.01) compared to epoetin-α. The optimal Hb target level (11 g/dl < Hb < 12 g/dl) was completely reached after 1 year of treatment with darbepoetin-α and in 70% of the patients treated with epoetin-α (p < 0.01). Cardiovascular performance (left ventricular end-diastolic volume, ejection fraction and pro-BNP) was significantly improved after darbepoetin-α treatment at the 6- and 12-month follow-ups compared to epoetin-α. Discussion: Despite the limitations of a retrospective observational study, these results encourage nephrologists to test the 1:300 darbepoetin/epoetin conversion ratio in 'easy' patients, and aggressive protocols for the treatment of anemia in CKD patients are avoided. Darbepoetin-α appeared effective in anemia correction, improving cardiovascular performance in a significantly higher proportion than epoetin. At low doses, on the other hand, it has to be borne in mind that a treatment regimen with only one submaximal administration per week may increase patient compliance and adherence to therapy, explaining in part the observed results.

Ultrasonography: Ariadne's Thread in the Diagnosis of the Cardiorenal Syndrome

The term cardiorenal syndrome (CRS) describes a broad spectrum of clinical conditions with four combinations of acute and chronic heart and kidney failure. Based on the pathophysiological primum movens, the actual classification recognizes five CRS types: in type I and II CRS, the initiating event is heart failure (acute or chronic), while it is kidney failure in type III and IV CRS; type V is linked to systemic diseases. Ultrasound techniques (echocardiography and ultrasonography of the kidney, inferior vena cava and chest) can be extremely helpful in establishing a prompt diagnosis and a correct CRS classification. Basic echocardiography allows evaluation of ventricular diastolic and systolic functions, investigates pulmonary congestion and pericardial effusion, and describes volume overload. On the other hand, renal ultrasound helps clinicians to distinguish between acute and chronic renal failure, excludes urinary tract dilation or pathological bladder repletion, and provides crucial information regarding kidney volume or echogenicity. Applying basic knowledge of echocardiography and renal ultrasound, nephrologists may be in a better position for patient treatment and management, bearing in mind that doctors can properly use a stethoscope although not being a cardiologist.

Does systematic preliminar colour Doppler study reduce kidney biopsy complication incidence?

While ultrasonography is widely performed prior to biopsy, colour Doppler examination is often used only to discover post-biopsy complications. Aim of this paper was to evaluate the usefulness of colour Doppler examination in planning the optimal site of puncture for renal biopsy. Present analysis includes 561 consecutive percutaneous renal biopsies performed from the same operator. Until August 2000 332 biopsies were performed after a preliminary ultrasonography (Group A). From September 2000, 229 patients underwent even a preliminary colour Doppler study (Group B). Postbioptic bleeding were categorized as minor (gross hematuria or subcapsular perinephric hematoma < 4 cmq of greater diameter) or major (hematoma >4 cmq of greater diameter; requiring blood transfusion or invasive procedures; leading to acute renal failure, urine tract obstruction, septicaemia, or death). Major complications were seen in 2.1% in Group A while in Group B only one case was reported (0.43%). Minor clinically significant complications occur in 7.8% in Group A and in 3.4% of cases of Group B. Colour Doppler reduced drastically the incidence of complications observed before the introduction of routine colour Doppler examination prior to biopsy. In our opinion, these data support the use of preliminary colour Doppler study when a biopsy is planned.

A complex renal cyst: it is time to call the oncologist?

Introduction. Hydatid disease is a cyclozoonotic parasitic infestation caused by the cestode Echinococcus granulosus. The cysts mainly arise in the liver (50 to 70%) or lung (20 to 30%), but any other organ can be involved, in abdominal and pelvic locations, as well as in other less common sites, which may make both diagnosis and treatment more complex. Isolated renal involvement is extremely rare. Case Presentation. We report a rare case of isolated renal hydatid disease in a 71-year-old man with a history of vague abdominal pain, anemia, fever, and microhematuria. Ultrasonographic examination revealed a complex cyst in the right kidney, including multiple smaller cysts with internal echoes. A magnetic resonance scan of the abdomen confirmed the findings, and hydatid cyst disease was diagnosed. Right nephrectomy was performed, and microscopic examination confirmed the diagnosis of hydatid cyst. Albendazole, 10 mg/kg per day, was given for 4 weeks (2 weeks preoperatively and 2 weeks postoperatively). Conclusion. Isolated primary hydatidosis of the kidney should always be considered in the differential diagnosis of any cystic renal mass, even in the absence of accompanying involvement of liver or other visceral organs.

Right ventricular diastolic function in dialysis patients could be affected by vascular access

Tricuspid annular plane excursion (TAPSE) measurement in echocardiography is a measure of heart diastolic distensibility: a low TAPSE indicates reduced ventricular distensibility leading to diastolic dysfunction. It is a good prognostic index for cardiac mortality risk in congestive heart failure patients, adding significant prognostic information to the NYHA clinical classification. Our study was designed to evaluate the effect of a single hemodialysis (HD) session on diastolic function and TAPSE, focusing on the effects of vascular access typology. Twenty chronically uremic patients (age 51 ± 10 years, dialytic age 24 ± 8 months), without overt heart disease, underwent conventional two-dimensional and Doppler echocardiography immediately before starting and 15 min after ending a mid-week HD session. Ten patients had distal radiocephalic arterovenous fistula (AVF), and 10 had permanent central venous catheters (CVC). The amount of fluid removed by HD was 2,706 ± 1,047 g/session. HD led to a reduction in TAPSE, left ventricle end-diastole volume, left ventricle end-systole volume, right ventricle end-diastole diameter, peak early transmitral flow velocity, and the ratio of early to late Doppler velocities of diastolic mitral flow. AVF patients showed greater right ventricle diameters versus CVC patients, while TAPSE appeared higher in the latter. Only the AVF patient group showed TAPSE values <15 mm. Our data confirm the effects of terminal uremia on right ventricle function (chamber dilation, impaired diastolic function), showing that these abnormalities are more frequent in AVF patients as opposed to CVC patients. It is reasonable to explain these clinical features as the effect of preload increase operated by AVF.

[Recurrent multifocal cancer lesions in a patient on hemodialysis after kidney pancreas transplant failure]

Cancer is an important cause of mortality in patients on hemodialysis and kidney transplant recipients. Immunodepression and the genotoxic action of uremia are critical pathogenic agents. A 59-year-old man, ex-smoker, who had been on hemodialysis for seven months because of uremic degeneration of diabetic nephropathy, underwent a combined kidney-pancreas transplant in 1991, complicated by slow-resolution CMV infection. In 1993, after kidney graft failure due to chronic rejection, hemodialysis treatment was restarted with good pancreatic function. Steroid therapy was interrupted and azathioprine and cyclosporine immunosuppressive therapy maintained. In September 2007 the patient was diagnosed with two neoplasms of the oral mucosa: a well-differentiated squamous carcinoma and a spinocellular carcinoma associated with field cancerization. The tumors were resected, followed by laser treatment. Histological examination revealed squamous cell carcinoma without lymph node involvement. Azathioprine was interrupted. In January 2008 adjuvant radiotherapy to the surgical areas of the oral mucosa and neck was started. In February a verrucous nevus on the patient's chest turned out to be a spinocellular carcinoma in situ. In May 2008 recurrence of keratinizing squamous carcinoma of the oral mucosa was found, this time with nodal involvement. Cyclosporine administration was interrupted and after consultation with the oncology committee it was decided to continue with supportive therapy only, until the patient's death in August 2008.

Genomic damage in endothelial progenitor cells from uremic patients in hemodialysis

INTRODUCTION

End stage renal disease (ESRD) is associated with a high incidence of cardiovascular disease and cancer. Patients undergoing hemodialysis show a reduced number and an impaired function of endothelial progenitor cells (EPCs), which in physiological conditions contribute to repair the vascular damage. In patients with ESRD, massive oxidative genome damage has been demonstrated but the role of HD in causing it is still a controversial issue. The aim of our study was to analyze the effects of a single HD session on the number of cells marked with CD34 (including sub-type cells known to be EPCs); we then evaluated the genomic damage in these cells using COMET assay.

PATIENTS AND METHODS

We quantified CD34(+) cells in blood samples in 30 patients in hemodiafiltration treatment for 3.5 to 4 hours 3 times/week and in 30 healthy volunteers. In HD patients, blood samples were drawn at different time intervals: start of dialysis (T(0)), at the end of the treatment (T(end)) and 24 hours afterwards in the interdialytic day (T(inter)). Staining and analysis was performed using the ISHAGE (International Society of Hematotherapy and Graft Engineering) guidelines. EPCs count was conducted using a multiparameter flow cytometric lyse no-wash method. Genomic damage was evaluated by Comet assay.

RESULTS

The number of CD34(+) cells in the HD patients at the beginning of the dialysis session (T(0)) was significantly lower than in healthy controls. HD patients showed a significant increase in CD34 number at the end of the session (T(end)) with respect to T(0). In the interdialytic period (T(int)), the number of CD34(+) cells was significantly reduced with respect to T(end). COMET assay performed on CD34(+) cells showed a higher basal level of genomic damage in HD patients than in controls; it increased in a statistically significant manner after the hemodialysis session, while in the interdialytic period it came back to T(0) level.

CONCLUSIONS

Uremic status is characterized by lower levels of circulating EPCs, which increase after a single session of HD together with genomic damage to the CD34(+) cells.

Osteoprotegerin and Bone Mineral Density in Hemodiafiltration Patients

A newly identified cytokine, osteoprotegerin (OPG) appears to be involved in the regulation of bone remodeling. In vitro studies suggest that OPG, a soluble member of the TNF receptor family of proteins, inhibits osteoclastogenesis by interrupting the intercellular signaling between osteoblastic stromal cells and osteoclast progenitors. As patients with chronic renal failure (CRF) often have renal osteodystrophy (ROD), we investigated the role of osteoprotegerin (OPG) in ROD, and investigated whether there was any relationship between serum OPG, intact parathyroid (PTH) (iPTH), vitamin D, and trabecular bone. Serum OPG combined with iPTH might be a useful tool in the noninvasive diagnosis of ROD, at least in cases in which the range of PTH values compromises reliable diagnosis. Thirty-six patients on maintenance hemodiafiltration (HDF) and a control group of 36 age and sex matched healthy subjects with no known metabolic bone disease were studied. The following assays were made on serum: iPTH, osteocalcin (BGP), bone alkaline phosphatase, 25(OH)-cholecalciferol, calcium, phosphate, OPG, IGF-1, estradiol, and free testosterone. Serum Ca++, P, B-ALP, BGP, IGF-1, iPTH, and OPG levels were significantly higher in HDF patients than in controls, while DXA measurements and quantitative ultrasound (QUS) parameters were significantly lower. On grouping patients according to their mean OPG levels, we observed significantly lower serum IGF-1, vitamin D3 concentrations, and lumbar spine and hip bone mineral density in the high OPG groups. No correlation was found between OPG and bone turnover markers, whereas a negative correlation was found between serum OPG and IGF-1 levels (r=-0.64, p=0.032). Serum iPTH concentrations were positively correlated with bone alkaline phosphatase (B-ALP) (r=0.69, p=0.038) and BGP (r=0.92, p<0.001). The findings made suggest that an increase in OPG levels may be a compensatory response to elevated bone loss. The low bone mineral density (BMD) levels found in the high OPG group might have been due to the significant decrease in serum IGF-1 and vitamin D3 observed. In conclusion, the findings made in the present study demonstrate that increased OPG in hemodiafiltration patients is only partly due to decreased renal clearance. As it may partly reflect a compensatory response to increased bone loss, this parameter might be helpful in the identification of patients with a marked reduction in trabecular BMD.

Management of Patients after Renal Graft Loss: An Open Question for Nephrologists

Patients undergoing renal graft failure and returning to dialysis are often regarded to like facing for the first time a substitutive treatment, without considering the technical complications, the economical impact, and the psychological implications. This review attempt, to give answers to various questions, concerning the management of vascular access, the immunosuppressive therapy, the transplantectomy, the emotional and neuropsychic aspects, and the quality of life of graft-failed patients.

A case-by-case protocol of membranous nephropathy treatment with endovenous infusion of high doses of human immunoglobulins

The treatment of membranous nephropathy is a highly controversial issue. As some patients may have spontaneous remission, in about 50% of cases the risk of treating patients with drugs that may have severe side effects is higher than the potential benefit of arresting disease progression. Some authors therefore propose exclusively symptomatic treatment; other authors use steroids and immunosuppressive drugs, alone or in association with high risk of adverse effects and often uncertain benefits. The intravenous administration of high doses of human immunoglobulins (IVIg) has been also extended to a growing number of kidney diseases including membranous nephropathy. The mechanisms through which IVIg carry out their therapeutic effect are still unclear. The present study is a retrospective and uncontrolled trial, the aim of which was firstly to verify if some patients could respond to extremely short treatment protocols, stopped when they appear to have a stable remission, thereby avoiding expensive continuation of treatment. Secondly, we aimed to verify if some patients, judged as nonresponders to a classical protocol of IVIg therapy, could respond to a more prolonged treatment.

[Intravenous immunoglobulins in the treatment of glomerulopathies]

Intravenous high-dose immunoglobulin (IVIG) therapy is used in several antibody-mediated diseases including Guillain-Barré syndrome, idiopathic thrombocytopenic purpura, and autoimmune neuropathies. In the last decade, numerous studies have evaluated the application of IVIG therapy in autoimmune glomerulopathies such as lupus nephritis, membranous glomerulonephritis, and transplant-related chronic nephropathy. These studies were conducted on small numbers of patients and varied with respect to IVIG doses and duration of therapy cycles. Furthermore, many of the patients included in the studies did not respond to conventional therapies, were affected by complications, and had impaired renal function. IVIG therapy was able to reduce proteinuria and inflammation and improve renal function in some forms of glomerulonephritis, particularly LES-related forms. IVIG therapy was also tested in patients awaiting kidney transplantation and in patients affected by transplant-related chronic nephropathy: in both groups the results were controversial. Seventy-eight cases of IVIG-related nephrotoxicity have been reported in the literature. In most cases the toxic effect was reversible and observed in patients with pre-existing renal failure treated with IVIG formulations containing saccharose. IVIG could have beneficial effects in many glomerulopathies. Nevertheless, further trials are needed to clarify the potential and the limitations of this therapeutic approach.

Circadian rhythm of hydration in healthy subjects and uremic patients studied by bioelectrical impedance analysis

BACKGROUND

Healthy subjects and patients after successful kidney transplantation show a circadian rhythm for glomerular filtration rate and for the glomerular transport of macromolecules. We aimed to evaluate by bioelectrical impedance analysis (BIA) whether body hydration status also follows a circadian rhythm in patients with impaired renal function.

METHODS

The study was conducted on 28 subjects divided into 3 groups: 8 healthy volunteers, 8 patients affected by chronic kidney disease and 12 end-stage renal disease (ESRD) patients on hemodialysis. During 24 h, 9 BIA measurements were taken in every subject every 180 min.

RESULTS

BIA findings demonstrate that normal subjects have a circadian rhythm in hydration status that reaches maximum body water content at night, between 21.00 and 23.00 h. In patients with chronic kidney disease, this rhythm, with maximum at night, is maintained. The rhythm is also present in ESRD patients, if the residual diuresis is at least 500 ml/day, while there is no rhythm when residual diuresis is <300 ml/day.

CONCLUSIONS

In normal subjects, body hydration status shows a circadian rhythm, which is weakened or lost in oligoanuric patients on dialysis, but partially maintained in subjects with preterminal uremia and in hemodialyzed patients with residual diuresis >500 ml/day.

Nitric oxide generation is associated with an unbalance of protein tyrosine phosphatases during liver transplantation

Organ dysfunction secondary to ischemia-reperfusion (I/R) injury still represents a major problem in liver transplantation. Apoptosis has been observed in hepatocytes and sinusoidal endothelial cell, following I/R injury and it has been postulated as a contributing factor in ischemia-reperfusion graft dysfunction, involving a complex series of events, as changes of protein tyrosine-kinase phosphorylation. We evaluated hepatic purine metabolites, protein tyrosine phosphatases (PTPs), nitrate plus nitrite levels (NOx), caspase-3 (C-3) activity and DNA fragmentation in the time course of twelve pig orthotopic liver transplantation. Biopsies were taken before explantation (t0), after cold ischemic storage (t1) and 30 min from reperfusion (t2). During the ischemic period we observed a reduction of high energy phosphates and an increase of purine bases; PTP activity was largely increased. At t2 high energy phosphates showed a tendency to increase with respect to t1, with a partial restoration of phosphorylation potential, measured as ATP/ADT ratio. PTP activity was significantly reduced, with a concomitant increase of NOx production and C-3 activity; in a considerable number of cases we observed a sustained DNA fragmentation. We speculate that NOx production could be related to nitrosative stress, which in turn leads to dynamic alteration in PTP balance and cell signalling, regulating the activity of a number of proteins implicated in apoptotic cell death. These findings could be of interest in new potential strategy to prevent and treat I/R injury.

Statins in the prevention of cardiovascular events in patients with renal failure

HMG-CoA reductase inhibitors (statins) are among the most widely used hypolypemizing drugs with a pleiotropic activity. Numerous clinical trials have demonstrated that statins can have a significant effect in the prevention of cardiovascular diseases in the general population. In patients with renal failure, this drug preserves the hypolypemizing efficacy found in the general population without increasing their unwanted side-effects. The re-analysis of data from epidemiological studies conducted on the general population has confirmed that statins provide cardiovascular protection also in subjects with renal failure. These data have been partly confirmed by the findings made by 4D (Die Deutsche Diabetes Dialyse Studie) and Alert studies, conducted on diabetic patients on dialysis and patients with renal transplants, respectively. The results of other studies, such as AURORA, SHARP, REnal and Vascular End stage Disease, and ESPLANADE, clearly indicate that statins prevent cardiovascular disease in patients with renal insufficiency, just as they do in the general population.

Purine metabolism in B-cell lymphocytic leukemia: a microarray approach

B-cell chronic lymphocytic leukemia (B-CLL) is an adult-onset highly heterogeneous malignancy characterized by a cells resistance to apoptosis rather than to highly proliferative cells. In previous research, we evidenced an imbalance of purine metabolism in B-CLL cells. Since the extracellular adenosine has been proved to induce apoptosis via A2b receptor, enzymes involved in adenosine metabolism could play an important role in apoptosis resistance of B-CLL cells. We prepared a microarray chip for the analysis of 50 selected genes that could be of interest in B-CLL: enzymes of purine de-novo, salvage and catabolic pathway, oxidative stress enzymes, and apoptotis-related proteins. Preliminary results identify many genes of purine metabolism that exhibit low or high expression, while genes involved in signal transduction and apoptosis exhibit lower alterations even if of remarkable interest. This application of microarray technique seems promising and at least a subset of these genes will be valid candidates for further studies.

Dialysis-related genotoxicity: sister chromatid exchanges and DNA lesions in T and B lymphocytes of uremic patients. Genomic damage in patients on hemodiafiltration

BACKGROUND/AIMS

Patients with chronic renal failure show the presence of massive oxidative genome damage but the role played by dialysis is still a controversial issue. The aim of our study was to verify the genomic damage in B- and T-lymphocyte subpopulations of uremic patients after a single hemodiafiltration session.

METHODS

We enrolled 30 patients on maintenance acetate-free biofiltration and 25 age-matched healthy volunteers and studied chromosomal alterations.

RESULTS

Our data show that the basal levels of DNA damage, the number of sister chromatid exchanges and basal high-frequency cells levels are significantly higher in patients on hemodiafiltration than in controls and in T lymphocytes than in B cells.

CONCLUSIONS

These findings suggest that hemodialytic treatment could represent a potential source of damage, maybe through the oxidative action of the extracorporeal circuit components, which might explain the well-known T-specific immunodeficiency correlated with uremia.

Oxidative stress, sister chromatid exchanges and apoptosis in the pathogenesis of lymphocytopenia in ESRD patients

BACKGROUND

In end-stage renal disease (ESRD) patients on hemodialysis (HD) there may be a link between oxidative stress, genomic damage and the tendency of peripheral lymphocytes to die by apoptosis. Our aim was to verify this hypothesis, and to ascertain whether the link, if present, could explain lymphopenia in uremic patients.

METHODS

The series investigated comprised 55 participants: 30 HD patients on regular maintenance acetate-free bio-filtration (AFB) and 25 age-matched healthy volunteers. One blood sample was drawn from the cubital vein of each participant. In HD patients, samples were drawn 3 times: predialytic, postdialytic and interdialytic (24 hours after the end of the session). Thiobarbituric acid reactants (TBARs), sister chromatid exchange (SCE) rate, high frequency cells (HFCs), total circulating lymphocytes and the percentage of circulating apoptotic lymphocytes were assayed in all samples. A statistical analysis of the findings was made using multiple and linear regression.

RESULTS

In AFB patients, TBAR levels appeared higher than in controls, even at baseline (2.15 +/- 0.5 micromol/L vs. 1.20 +/- 0.4 micromol/L; p < 0.05). The highest peak occurred at the end of the session (3.2 +/- 0.4 micromol/L; p < 0.05 vs. basal), and a prompt return to basal values was observed 24 hours later (2.2 +/- 0.6 micromol/L, p < 0.5 vs. basal). In AFB patients, the per-centages of HFCs (8.63% vs. 3%; p < 0.05), SCE (6 +/- 0.6 vs. 4.65 +/- 2.18; p < 0.04) and apoptotic lymphocytes (3-fold) were greater than in controls, even at baseline, whereas the values for total lymphocytes were lower (1,140 +/- 652 vs. 1,590 +/- 822). After an AFB session the differences between patients and control values appeared greater (HFCs, 16.81%, p < 0.04 vs. basal; SCE, 7.02 +/- 1.2, p < 0.03; apoptotic lymphocytes 3.5-fold greater than control values). Twenty-four hours later, a further increase was observed in the expression of genomic damage (HFCs, 50%, p < 0.05 vs. basal; SCE, 9.82 +/- 2.1, p < 0.03) and the percentage of apoptotic lymphocytes (4.7-fold greater than control values), while the lowest peak occurred for total circulating lymphocyte count (997 +/- 854, p < 0.04). At linear regression, a strong positive correlation was found between HFCs and TBARs at the beginning and at the end of the AFB session(r = 0.7, p < 0.03). With multiple regression analysis, a strong positive correlation was found between TBAR levels at the end of AFB session, HFC rate and apoptotic lymphocytes at 24 hours, with the last as the dependent variable (multiple r = 0.8, TBARs, beta = 0.51, p < 0.04; HFCs, beta = 0.43, p < 0.03).

DISCUSSION AND CONCLUSIONS

An AFB session has an immediate impact, causing an increase in TBAR levels, genomic da-mage and lymphocytic apoptosis. Twenty-four hours after the session there was a further expression of genomic damage, and an increase in apoptosis, while the peak for lymphocytes dropped sharply. Our findings indicate that lymphopenia affecting end-stage renal disease (ESRD) patients may be strictly related to genomic damage exerted, at least in part, by TBARs, and to a dysregulation in programmed cell death.

Chromosomal damage and atherosclerosis. A protective effect from simvastatin

In uremic patients, the frequency of sister chromatid exchanges appears markedly higher than in the general population. Statins are well known for their pleiotropic effects, which are independent of any reduction in cholesterol circulating levels. The aim of the present study was to determine the effects of exposure to escalating doses of simvastatin on the sister chromatid exchange rate in cultured lymphocytes in order to identify the influence of statin on genomic damage. Peripheral lymphocytic samples for culture were obtained from 25 healthy volunteers, 20 patients with documented carotid atherosclerosis and 30 atherosclerotic patients on maintenance regular acetate-free biofiltration. Hemodialyzed patients had a greater percentage of high frequency cells (50%) than healthy controls (3%) and a significantly higher average number of sister chromatid (9.82+/-2.1 vs. 4.65+/-2.18). The subgroup of hemodialyzed patients with high plaque score values was characterized by significantly greater values for both sister chromatid exchanges rate and high frequency cells percentage. Our findings demonstrate that there is an association between sister chromatid exchanges and high frequency cells rate and atherosclerosis in acetate-free biofiltration patients. In cultures with added simvastatin, high frequency cells percentages and mean sister chromatid exchanges levels were significantly lower than in cultures with an added vehicle alone, the reduction occurring in a dose-dependent fashion, above all in cultures from end stage renal disease patients. The findings, moreover, demonstrate new effects of simvastatin, which appeared to mitigate the expression of genomic damage in our model. However, it is not yet clear whether this effect is due to the prevention of genomic damage or to the potentiation of the DNA repair capacity. Statins may therefore have an anti-atherogenic action partly ascribable to their ability to provide protection against the development of atherosclerotic plaque.

Brain and cancer: the protective role of erythropoietin

Erythropoietin (Epo) is a pleiotropic agent, that is to say, it can act on several cell types in different ways. An independent system Epo/Epo receptor (EpoR) was detected in brain, leading to the hypothesis that this hormone could be involved in cerebral functions. Epo/EpoR expression changes during ontogenesis, thus indicating the importance of this system in neurodevelopment. Moreover, the hypoxia-induced production of Epo in the adult brain suggests that it could exert a neurotrophic and neuroprotective effect in case of brain injury. Epo could also influence neurotransmission, inducing neurotransmitters (NT) release. Epo therapy in anemic cancer patients is still a controversial issue, because of its possible action as a growth and an angiogenic factor. In our speculative hypothesis Epo could be involved in a "two steps process" that, after a neovascularization phase, leads to its down regulation. Moreover, Epo-activated signaling pathways could be modulated as possible targets to interfere in neoplastic cells cycle. In conclusion, treatment with rHuEpo could change therapeutical perspectives in different pathological conditions, such as central nervous system (CNS) diseases, but further studies are needed to clarify its physiopathological activities in different clinical fields.

QTc interval and QTc dispersion during haemodiafiltration

BACKGROUND AND AIM

Our aim was to evaluate QTc interval and QTc dispersion in 27 end-stage renal disease (ESRD) patients undergoing Acetate Free Biofiltration (AFB) in order to ascertain any correlations between the electrrocardiographic (ECG) parameters, serum Na+, K+, Ca++, Mg++ and intraerythrocytic Mg++ (Mg++e) concentrations. All measures were made at t0 (session beginning), t1 (first hour), t2 (second hour), t3 (third hour), and t4 (session end).

RESULTS

Blood pressure, heart rate, bodyweight and total ultrafiltration in the three dialysis sessions were constant. A significant progressive increase occurred in serum Ca++ during the sessions, while there was a significant diminution in serum K+. The pattern for Mg++ concentrations in serum and erythrocytes differed: in serum it decreased, whereas Mg++e increased. At t4, the QTc interval was reduced to a significant extent with respect to the baseline value. QTc dispersion significantly increased at t1 without there being significant variations at other times with respect to t0. At t2, t3 and t4, values promptly returned to baseline levels. QTc had a negative correlation with serum Ca++ levels at t4. In contrast, an inverse correlation was found between QTc dispersion and serum K+ at t1. No other correlations could be found between any other electrolytes, QTc interval or QTc dispersion.

CONCLUSION

In conclusion, the decrease observed in the QTc interval at the end of an AFB session was inversely related to serum Ca++ concentrations. Moreover, an increase in QTc dispersion occurred during the first hour of the session, and was negatively correlated with serum K+.

The effect of two different protocols of potassium haemodiafiltration on QT dispersion

BACKGROUND

The risk of developing cardiovascular diseases is higher in patients on haemodialysis than in the general population. These patients may develop arrhythmias that depend on the extra- and intracellular concentrations of potassium. ECG findings, particularly the QT interval and its dispersion (QT(d)) and the QT(c) (QT interval corrected for heart rate according to Bazett's formula) and its dispersion (QT(cd)), may be direct indicators of the risk of developing arrhythmia.

METHODS

Our cohort comprised 28 patients who were dialysed for 3.5-4 h three times per week, first with haemodiafiltration with a constant potassium concentration (HDF) in the dialysis bath then with haemodiafiltration with variable concentrations of potassium (HDF(k)). ECGs were done at different time intervals: at the start of dialysis (T(0)), at 15 (T(15)), 45 (T(45)), 90 (T(90)) and 120 min (T(120)) after the beginning of the session, and at the end of treatment (T(end)). ECG-derived data (QT, QT(d), QT(c) and QT(cd)) were measured. At the same time points, plasma electrolytes, intra-erythrocytic potassium and the electrical membrane potential at rest (REMP) of the erythrocytic membrane were measured.

RESULTS

Plasma potassium concentration diminished more gradually in HDF(k) than in HDF, the difference being statistically significant at T(15) and T(45) (P<0.05), and T(90) (P<0.01). The intra-erythrocytic potassium concentration remained constant throughout the observation period. In both HDF and HDF(k), REMP was lower at all points after T(0) (P<0.05), but the reduction was greater and more significant in HDF than in HDF(k) at T(15) and T(120) (P<0.05). ECG revealed a statistically significant diminution in HDF(k) vs HDF in the measures of dispersion of QT and QT(c) at T(15), T(90), T(120) and T(end) (P<0.01) and of QT(cd) at T(45) (P<0.05). The mean of QT(d), adjusted for plasma potassium, increased over time in HDF with large alternate mean increase and decrease peaks and error intervals. In HDF(k), instead, there was a progressive and constant diminution with minor error intervals. QT(cd) adjusted for plasma potassium had the same trend. A marked difference was found between the final values in standard HDF and those in HDF(k).

CONCLUSIONS

HDF and HDF(k) have significantly different effects on QT(c). ECG data demonstrate that the risk of arrhythmia could be lower, with a variable removal of potassium during haemodialysis. With HDF but not HDF(k), hyperpolarization of the cell membrane is detected, and this could have a destabilizing effect on different types of cardiac cell, giving rise to retrograde circuits.