Color Doppler ultrasound evaluation of arteriovenous grafts for hemodialysis.

Although arteriovenous fistula (AVF) continues to be the vascular access of choice for the hemodialysis, arteriovenous graft (AVG) can be the best choice in certain categories of patients and could have several advantages over AVF in a "patient centered approach" to vascular access. In the clinical management of prosthetic fistulas, color Doppler ultrasound (CDU) is the imaging method of choice for identifying stenosis and other AVG complications. In this review, besides highlighting the pivotal role of CDU in the diagnosis of AVG complications, we will underline the key role that ultrasound can play in identifying those stenosis most likely to cause AVG thrombosis. Furthermore, we will emphasize the support that CDU can play in distinguishing the different types of grafts and prosthetic devices such as stent-grafts, in identifying AVG with lower survival, CDU utilities and limitations in the evaluation of freshly-implanted grafts, the different sites available for AVG volume flow measurement and their use based on the configuration of the prosthesis, the time interval elapsed from the surgical intervention and the integrity of the prosthetic walls.

Author Correction: The copy number variation landscape of congenital anomalies of the kidney and urinary tract.

In the version of this article initially published, affiliation 38 incorrectly read "ICNU-Nephrology and Urology Department, Barcelona, Spain"; "Renal Division, Hospital Clinic, IDIBAPS, University of Barcelona, Barcelona, Spain" is the correct affiliation. The error has been corrected in the HTML and PDF versions of the article.

The copy number variation landscape of congenital anomalies of the kidney and urinary tract.

Congenital anomalies of the kidney and urinary tract (CAKUT) are a major cause of pediatric kidney failure. We performed a genome-wide analysis of copy number variants (CNVs) in 2,824 cases and 21,498 controls. Affected individuals carried a significant burden of rare exonic (that is, affecting coding regions) CNVs and were enriched for known genomic disorders (GD). Kidney anomaly (KA) cases were most enriched for exonic CNVs, encompassing GD-CNVs and novel deletions; obstructive uropathy (OU) had a lower CNV burden and an intermediate prevalence of GD-CNVs; and vesicoureteral reflux (VUR) had the fewest GD-CNVs but was enriched for novel exonic CNVs, particularly duplications. Six loci (1q21, 4p16.1-p16.3, 16p11.2, 16p13.11, 17q12 and 22q11.2) accounted for 65% of patients with GD-CNVs. Deletions at 17q12, 4p16.1-p16.3 and 22q11.2 were specific for KA; the 16p11.2 locus showed extensive pleiotropy. Using a multidisciplinary approach, we identified TBX6 as a driver for the CAKUT subphenotypes in the 16p11.2 microdeletion syndrome.

High-flow arteriovenous fistula and heart failure: could the indexation of blood flow rate and echocardiography have a role in the identification of patients at higher risk?

BACKGROUND: Although only high-flow arteriovenous fistulas (AVFs) are postulated to cause high-output cardiac failure (HOCF), there are currently no universally accepted criteria defining a high-flow fistula. METHODS: To verify if vascular access blood flow (Qa) ≥ 2000 ml/min provides an accurate definition of high-flow fistula, we selected 29 consecutive patients with Qa ≥ 2000 ml/min at color-duplex ultrasound examination and assessed them for the presence of cardiac failure symptoms; transthoracic echocardiography was also performed. RESULTS: Nineteen patients (65%) had heart failure symptoms and were classified with HOCF. At receiver operating characteristic (ROC) curve analysis, Qa ml/min values did not identify patients with heart failure symptoms but when AVF blood flow was indexed for height2.7, Qa ≥ 603 ml/min/m2.7 detected the occurrence of HOCF with good accuracy (sensitivity 100%, specificity 60%, efficiency 86%, positive predictive value 83%, negative predictive value 100%, area under curve 0.75). At echocardiographic evaluation, patients with Qa ≥ 603 ml/min/m2.7 had a more severe increase of left ventricular mass (63 ± 18 vs. 47 ± 7 g/m2.7, p < 0.003), left ventricular diastolic volume (140 ± 42 vs. 109 ± 14 ml, p < 0.007), left atrial volume (53 ± 23 vs. 39 ± 5 ml/m2, p < 0.015), a higher incidence of diastolic dysfunction (70 vs. 17%, p < 0.019) and higher CO reduction after AVF manual compression (2151 ± 875 vs. 1292 ± 527 ml/min, p < 0.009) than patients with Qa < 603 ml/min/m2.7. CONCLUSIONS: Indexation of AVF blood flow should be considered in defining high-flow fistula because the effect of Qa may differ in individuals of different sizes. A Qa value ≥ 603 ml/min/m2.7 and its association with some echocardiographic alterations could identify patients at higher risk for HOCF.

pCO2 Reveals Arteriovenous Fistula Recirculation in Bicarbonate Hemodialysis (RecirCO2lation Test).

We propose arterial pCO2 as test to discover vascular access recirculation (VAR) in bicarbonate hemodialysis (HD). We selected 30 HD patients with a ascertained well-functioning arteriovenous fistula (Control). In these patients, we artificially created VAR through the reversion of HD lines (Reversed). Results of the arterial gas analysis were collected at the start of HD (baseline) and after 5 min. At baseline, no differences of pH, pCO2 and HCO3 were found between the 2 groups. At 5 min, pCO2 increased from 38.1 ± 3.3 to 47.2 ± 6.3 mm Hg (p < 0.0001) in Reversed, whereas no increase was found in Control (p = 0.052). Areas under curve of pCO2-increase was 0.96 (0.91-1.00) and pCO2 at 5 min 0.92 (0.85-0.98). pCO2-increase >4.5 mm Hg showed sensitivity 86.7% and specificity 100% with positive predictive value (PPV) 100% and negative predictive value (NPV) 89%. A pCO2 value above 43 mm Hg at 5 min showed sensitivity 80%, specificity 90%, PPV 89%, NPV 82%. pCO2 increase >4.5 mm Hg and/or pCO2 at 5 min >43 mm Hg may accurately detect VAR.

Color Doppler ultrasound and arteriovenous fistulas for hemodialysis.

Native arteriovenous fistula (AVF) is the vascular access of choice for hemodialysis patients. Compared with grafts and central venous catheters, AVFs last longer and are associated with fewer complications. The widespread use of the Doppler ultrasound (DUS) has increased the number of patients who are eligible for AVF by facilitating the identification of vessels that are suitable for fistula construction (preoperative vascular mapping). DUS can also extend native AVF survival by improving the early detection of complications (post-operative surveillance). It is the only imaging modality that furnishes both morphological and functional data on the native vascular access, and it is also the only imaging tool that can be used directly by the surgeon, an indisputable advantage. This review examines the numerous roles played by DUS in the construction and postoperative follow-up of AVFs, including preoperative vascular mapping, AVF maturation, and surveillance.

[Acute reversible carpal tunnel syndrome following arteriovenous fistula surgery]. / Sindrome acuta del tunnel carpale dopo intervento di fistola arterovenosa.

We report a rare case of hand pain acutely experienced after arteriovenous placement with vascular derangement playing an etiopathogenetic key role and misleading neurological features due to a painless and misunderstood carpal tunnel syndrome. It cannot be explained by any well-defined pathophysiologic mechanism underlying the hand pain syndrome of hemodialysis patient. It is worth to note that the pain spontaneously relieved within few weeks in accordance with the time of transient tissue hypoxia triggered by fistula construction. In conclusion, an accurate neurological examination is mandatory in planning phase of vascular access, especially in the presence of special features or risk factors. Nevertheless, we would like to stress that the nephrologists must keep in mind that the wide range of ischemic damage caused by the arteriovenous fistula includes not only necrotic damage but also transient tissue hypoxia. The latter can spontaneously regress within few weeks, so that any deferrable decision must be postponed for at least thirty days.

[Chest ultrasound in nephrology]. / L'ecografia polmonare in Nefrologia.

The pulmonary study represents a constant appointment for Nephroplogist who frequently asks for a chest-xray in the nephrologic patient, especially in dialysis therapy. The chest x-ray and the Computed Tomography are normally used in pulmonary study, but they are not always rapidly executable and not practicable in the ambulatory and in dialysis room. The ultrasonography has recently been proposed for the study of the lung because it can be carried out rapidly in every nephro-dialytic room, also in frequent follow-up and it doesn't need particular equipment and probes. In this paper we present the fundamental notions of the management of a correct pulmonary ultrasonographic examination and some of the most common pathological pictures (pleural effusion, interstitial and alveolar syndrome, pneumothorax, etc).

[Assessment of correct positioning and complications after insertion of central venous catheters using chest radiography]. / La radiografia del torace nella valutazione del corretto posizionamento e delle complicanze del catetere venoso centrale.

The central venous catheter (CVC) is a very common procedure in the daily medical practice. In fact the CVCs are used to administer liquids and chemotherapeutics, the parenteral nutrition management, the measurement of the central venous pressure, the administration of hemodialysis. The international guidelines recommends always verifying the correct positioning of the tip of the CVC and to identify possible complications before his use. In the clinical practice the radiography of the chest represents the technique used more diffusedly for the control of the positioning and the possible precocious complications of the temporary and permanent CVCs positioned in the central veins. The integrated use of conventional radiology, above all digital of last generation, spiral computed tomography and ultrasounds allows to nearly have in every situation the answers for a correct diagnosis. The nephrologist, necessarily brought to deal with CVC, cannot refuse from a knowledge of such tools.

[Contrast enhanced ultrasound in renal diseases]. / L'imaging ecocontrastografico nella patologia renale.

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.

[Color-Doppler imaging and arteriovenous fistula: preoperative evaluation and surveillance]. / Eco-color-Doppler e fistola artero-venosa: utilizzo pre e post-chirurgico.

The native arteriovenous fistula (AVF) is the preferred vascular access for hemodialysis because of the lower incidence of complications and longer survival in comparison to grafts and central venous catheters. The use of color-Doppler sonography in the surgery of vascular accesses has increased the number of patients that are eligible for AVF as it allows to optimize the search for vessels suitable for surgical intervention (preoperative vascular mapping). Furthermore, color-Doppler imaging (CDI) has improved the survival of native AVF by increasing the early diagnosis of complications (postoperative surveillance). CDI is the only imaging technique able to provide both morphological and functional information about native vascular access and it is the only tool directly available to the nephrologist. This aspect is undoubtedly an additional value. Here we present a survey of the applications of CDI in the surgery and followup of AVF, with particular reference to preoperative mapping, AVF maturation and surveillance.

[Ultrasound assessment in renal infections]. / L'ecografia nelle infezioni del rene.

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.

[Vascular complications following kidney transplant: the role of color-Doppler imaging]. / Le complicanze vascolari del rene trapiantato: il ruolo dell'eco-color-Doppler.

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 in nephrology]. / L'ecocardiografia in nefrologia.

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.

[Management of color-Doppler imaging in dialysis patients]. / Il nefrologo e la gestione ecocolorDoppler del paziente in dialisi.

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.

Geographic differences in genetic susceptibility to IgA nephropathy: GWAS replication study and geospatial risk analysis.

IgA nephropathy (IgAN), major cause of kidney failure worldwide, is common in Asians, moderately prevalent in Europeans, and rare in Africans. It is not known if these differences represent variation in genes, environment, or ascertainment. In a recent GWAS, we localized five IgAN susceptibility loci on Chr.6p21 (HLA-DQB1/DRB1, PSMB9/TAP1, and DPA1/DPB2 loci), Chr.1q32 (CFHR3/R1 locus), and Chr.22q12 (HORMAD2 locus). These IgAN loci are associated with risk of other immune-mediated disorders such as type I diabetes, multiple sclerosis, or inflammatory bowel disease. We tested association of these loci in eight new independent cohorts of Asian, European, and African-American ancestry (N = 4,789), followed by meta-analysis with risk-score modeling in 12 cohorts (N = 10,755) and geospatial analysis in 85 world populations. Four susceptibility loci robustly replicated and all five loci were genome-wide significant in the combined cohort (P = 5×10⁻³²-3×10⁻¹°), with heterogeneity detected only at the PSMB9/TAP1 locus (I²â€Š= 0.60). Conditional analyses identified two new independent risk alleles within the HLA-DQB1/DRB1 locus, defining multiple risk and protective haplotypes within this interval. We also detected a significant genetic interaction, whereby the odds ratio for the HORMAD2 protective allele was reversed in homozygotes for a CFHR3/R1 deletion (P = 2.5×10⁻4). A seven-SNP genetic risk score, which explained 4.7% of overall IgAN risk, increased sharply with Eastward and Northward distance from Africa (r = 0.30, P = 3×10⁻¹²8). This model paralleled the known East-West gradient in disease risk. Moreover, the prediction of a South-North axis was confirmed by registry data showing that the prevalence of IgAN-attributable kidney failure is increased in Northern Europe, similar to multiple sclerosis and type I diabetes. Variation at IgAN susceptibility loci correlates with differences in disease prevalence among world populations. These findings inform genetic, biological, and epidemiological investigations of IgAN and permit cross-comparison with other complex traits that share genetic risk loci and geographic patterns with IgAN.

[Use of ECG-EC in the positioning of central venous catheters]. / Elettrocardiografia endocavitaria nel posizionamento dei cateteri venosi centrali.

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.