[Calcified Fibrin Sheath After Stuck Catheter Removal: Case Report and Literature Review].

The prevalence of central venous catheters (CVC) in hemodialysis patients is around 20-30%. In this scenario, complications related to the use of the CVC are commonly observed, requiring active management by nephrologists. These include infectious complications as well as those related to CVC malfunction. Among the latter, the formation of a fibrin sheath around the catheter linked to foreign body reaction could cause CVC malfunction in various ways. Even after the removal of the catheter, the fibrin sheath can remain inside the vascular lumen (ghost fibrin sheath) and rarely undergo calcification. We describe the clinical case of a hemodialysis patient who, following the removal of a malfunctioning, stuck CVC, presented a calcified tubular structure in the lumen of the superior vena cava, diagnosed as calcified fibrin sheath (CFS). This rare occurrence, described in the literature in 8 other cases, although rare, is certainly underdiagnosed and can lead to complications such as sepsis resulting from CFS, pulmonary embolisms, and vascular thrombosis. Therapeutic approaches should be considered only in symptomatic cases and involve an invasive surgical approach.

Endovascular tools for vascular access stenosis: Flow-chart proposal.

Stenosis represents the most relevant arteriovenous fistula (AVF) pathology and can affects the entire conduit forming the fistula, from afferent artery to central venous vessels. Correction of vascular access stenosis significantly affects the survival and quality of life for end stage renal disease patients (ESRD) dependent on hemodialysis. Guidelines consider the procedure of percutaneous transluminal angioplasty (PTA) relevant for the primary treatment of these lesions with excellent results in restoring AVF immediately at the end of the procedure. From first AVF angioplasty in 1981 to now, wide scientific innovation has led to development of new devices, composed by different materials and technologies, specific for the site and the type of stenosis to be treated, able to manage resistant stenotic lesion and to reduce stenosis recurrences. International guidelines do not clearly specify all treatment possibilities in the individual case. In this review the authors want to provide specific information on most used devices for stenosis treatment based on literature evidence, showing when and where to use the various tools available with flow-chart treatment proposal.

[New Therapeutic Strategies in the Treatment of CKD Anemia: Hypoxia-Induced Factor Prolyl-Hydroxylase Inhibitors].

The link between chronic renal failure and anemia has been known for more than 180 years, negatively impacting the quality of life, cardiovascular risk, mortality, and morbidity of patients with chronic kidney disease (CKD). Traditionally, the management of anemia in CKD has been based on the use of replacement martial therapy, vitamin therapy, and the use of erythropoiesis-stimulating agents (ESAs). In recent years, alongside these consolidated therapies, new molecules known as hypoxia-induced factor prolyl-hydroxylase inhibitors (HIF-PHIs) have appeared. The mechanism of action is expressed through an increased transcriptional activity of the HIF gene with increased erythropoietin production. The drugs currently produced are roxadustat, daprodustat, vadadustat, molidustat, desidustat, and enarodustat; among these only roxadustat is currently approved and usable in Italy. The possibility of oral intake, pleiotropic activity on martial and lipidic metabolism, and the non-inferiority compared to erythropoietins make these drugs a valid alternative to the treatment of anemia associated with chronic kidney disease in the nephrologist practice.

[Triple stenosis of brachio-basilic arteriovenous fistula: percutaneous transluminal angioplasty utility, case report and literature review].

The major haemodialysis arteriovenous fistula (AVF) complication is stenotic disease. It is represented by a reduction of the arterial or venous caliper forming the AVF. Most frequently it is located in the juxta- anastomotic region of the venous segment. There are a lot of mechanisms responsible for the stenosis formation; some are correlated by the shear stress in the wall of venous tract with a lot of biochemical mechanisms, others are associated with the repetition of venipuncture during haemodialisys treatment. It is recommended that each dialysis center activate an AVF monitoring program capable of identifying and treating stenosis. We describe a clinical case of a young woman with a multiple stenosis disease of a brachio-basilical transposed AVF.

CEUS-guided PTA on stenotic AVF: Morphological and functional point of view.

BACKGROUND: Stenosis represents the main cause of hemodialysis fistula malfunction. The ultrasound-guided angioplasty with ecographic contrast (CEUS) could provide further advantages to the classical ultrasound guided method improving the morphological characterization of the stenosis and providing quantitative data with the creation of time intensity curves (TIC) collecting functional data comparable between pre and post procedure. METHODS: A total of 10 CEUS-guided angioplasties were performed on malfunctioning fistulas. The sonographic contrast medium was injected into the vascular tree trough the introducer. Morphological and functional data nature were collected. Were generated TIC curves, obtained by positioning a ROI in correspondence with the post-stenotic tract of the efferent vein. The data collected, regarding the peak intensity reached by the signal (PI) and the time to reach the peak signal intensity (TTP), were compared in the pre and post-procedural phase with flow of vascular access (Qa) and resistance indices (RI). RESULTS: Statistically significant correlation (p < 0.05) was observed between Qa and TTP (r = 0.77; p = 0.009), RI and TTP (r = 0.71; p = 0.02), Qa and PI (r = 0.86; p = 0.0012), and between RI and PI (r = 0.88; p < 0.001). CONCLUSION: In addition to the advantages associated with the use of ultrasound contrast medium in improving the visualization and characterization of the stenosis by facilitating the PTA procedure, the functional data deriving from the quantitative analysis provide new parameters for evaluating the success of the procedure which could also be used as predictive markers of stenosis recurrence together with the classical ones.

[Sonographic artifacts in nephrology].

The huge spreading of sonography in the field of nephrology led to the use of more performant equipment with construction of better quality images, but with an unfavorable signal/noise ratio, that bring to the generation of artifacts: false signals which creates images not corresponding to reality. Interaction between ultrasounds and biological structures generates a lot of physical phenomena: reflection, dispersion, absorption and diffraction; these elements create not only the images but also the artifacts. The artifacts, which don't correspond to anatomic reality, could be related to the extreme difference of acoustic impedance between the biological structures, or to an error in the settings of B-Mode and color-doppler functions. Sometimes they can be dangerous and make a diagnosis hard, but most of the time they are useful and pathognomonic of a lesion or physiologic structure. It's fundamental for the sonographer being able to discern between real to artifact; the rule is that everything that is repeated in all scans with different insonation angles is true, while what is not repeated in all scans can be an artifact.

[Parameters predicting arterious-venous fistula maturation in pre surgery vascular mapping].

Arterious-venous fistula (AVF) represents the first-choice vascular access for haemodialysis. Pre-surgery evaluation is mandatory to identify the appropriate vessels and to predict the success of AVF creation. Echo-color Doppler provides a wealth of morphological and functional values useful to create an optimal vascular access for haemodialysis. The purpose of this study has been to identify pre-surgery echo-color Doppler parameters useful to predict AVF maturation. 44 patients were enrolled, and 44 AVF created. During pre-surgery evaluation we collected the following data: cephalic vein and radial artery calibers; radial artery flow and caliber; flow and resistive index (RI) of the brachial artery. We also performed a reactive hyperemia test. During the post-surgery evaluation after 30 days, we collected: AVF flow; resistive index of the brachial artery; post-anastomosis cephalic vein caliber. The results showed a direct correlation between AVF flow and some parameters: cephalic vein, radial artery and brachial artery caliber, reduction of RI after reactive hyperemia test and, in the post-surgery evaluation, between AVF flow and post-anastomosis cephalic vein caliber. We divided patients into two groups: "A", representative of AVF adequate maturation, and "B", representative of AVF early failure (EF) and AVF failure to mature (FTM). We observed some statistically significant differences in the two groups. With the creation of Receiver Operating Characteristic (ROC) curves we identified two parameters able to predict the AVF outcome (Δ IR = 0.15; Δ flow = 150 ml/m). This study identifies pre-surgery echo-color Doppler parameters that could be useful, together with others, to predict the outcome of the AVF creation.