bluuebunny/crossref_metadata_2025_split huggingface dataset:
Time-Resolved PIV Technique for High Temporal Resolution Measurement of Mechanical Prosthetic Aortic Valve Fluid Dynamics
Authors: Kaminsky R. , Morbiducci U. , Rossi M. , Scalise L. , Verdonck P. , Grigioni M. 
Published: January 2018

Prosthetic heart valves (PHVs) have been used to replace diseased native valves for more than five decades. Among these, mechanical PHVs are the most frequently implanted. Unfortunately, these devices still do not achieve ideal behavior and lead to many complications, many of which are related to fluid mechanics. The fluid dynamics of mechanical PHVs are particularly complex and the fine-scale characteristics of such flows call for very accurate experimental techniques. Adequate temporal resolution can be reached by applying time-resolved PIV, a high-resolution dynamic technique which is able to capture detailed chronological changes in the velocity field. The aim of this experimental study is to investigate the evolution of the flow field in a detailed time domain of a commercial bileaflet PHV in a mock-loop mimicking unsteady conditions, by means of time-resolved 2D Particle Image Velocimetry (PIV). The investigated flow field corresponded to the region immediately downstream of the valve plane. Spatial resolution as in “standard” PIV analysis of prosthetic valve fluid dynamics was used. The combination of a Nd:YLF high-repetition-rate double-cavity laser with a high frame rate CMOS camera allowed a detailed, highly temporally resolved acquisition (up to 10000 fps depending on the resolution) of the flow downstream of the PHV. Features that were observed include the non-homogeneity and unsteadiness of the phenomenon and the presence of large-scale vortices within the field, especially in the wake of the valve leaflets. Furthermore, we observed that highly temporally cycle-resolved analysis allowed the different behaviors exhibited by the bileaflet valve at closure to be captured in different acquired cardiac cycles. By accurately capturing hemodynamically relevant time scales of motion, time-resolved PIV characterization can realistically be expected to help designers in improving PHV performance and in furnishing comprehensive validation with experimental data on fluid dynamics numeric modelling.
First Two ABO-Incompatible Living Kidney Transplantations in the Balkans - Should it be a Procedure of Choice in a Developing Country?
Authors: Spasovski G.B. 
Published: January 2018

Kidney transplantation is the best available medical intervention for the treatment of end-stage renal failure. However, as a consequence of the growing gap between organ supply and demand, many patients die waiting for an organ each year. In order to increase the number of organs, living donor (LD) transplantation from unrelated and ABO-incompatible (ABOi) donors have been introduced over the last few decades. While in the past ABOi transplantation resulted in hyperacute or acute antibody-mediated rejection, the tremendous progress in this area in recent years has shown that it can be overcome by careful patient management, including protocols to remove or lower antibodies, along with stronger immunosuppression and intensive monitoring. The organ shortage problem is even more prominent in regions such as the Balkans where cadaver transplantation has not been well developed. In addition to the introduction of expanded criteria for living donation (elderly and marginal donors), we performed the first two ABOi/LD transplantations in the Balkans in the last 2 years using an already established preconditioning regimen and maintenance therapy with cyclosporine, mofetil mycophenolate and prednisolon. We report our modest experience of a case in which the patient developed lymphadenopathy sarcomatosis and died after one year; and a second case with accelerated acute rejection and hemorrhagic necrosis with explantation of the graft after a month. Taking into account the high cost of the desensitization procedure and induction therapy as well as the need for intensive monitoring throughout the standardized procedures and facilities, we might reconsider whether ABOi living kidney transplantation should be a procedure of choice in developing countries.
Citrate Anticoagulation during CVVH in High Risk Bleeding Patients
Authors: Cubattoli L. , Teruzzi M. , Cormio M. , Lampati L. , Pesenti A. 
Published: January 2018

Background Regional citrate anticoagulation (RCA) is an effective form of anticoagulation for continuous renal replacement therapy (CRRT) in patients with contraindications to heparin. Its use has been very limited, possibly because of the need for special infusion solutions and difficult monitoring of the metabolic effects. Objective To investigate the safety and the feasibility of an RCA method for continuous veno-venous hemofiltration (CVVH) using commercially available replacement fluid. Methods We evaluated 11 patients at high risk of bleeding, requiring CVVH. RCA was performed using commercially available replacement fluid solutions to maintain adequate acid-base balance. We adjusted the rate of citrate infusion to achieve a post-filter ionized calcium concentration [iCa] <0.4 mmol/L when blood flow was <250 ml/min, or <0.6 mmol/L when blood flow was >250 ml/min. When needed, we infused calcium gluconate to maintain systemic plasma [iCa] within the normal range. Results Twenty-nine filters ran for a total of 965.5 h. Average filter life was 33.6±20.5 h. Asymptomatic hypocalcemia was detected in 6.9% of all samples. No [iCa] values <0.9 mmol/L were observed. Hypercalcemia (1.39±0.05 mmol/L) occurred in 2.5% of all samples. We observed hypernatremia (threshold 153 mmol/L) and alkalosis (threshold 7.51) in only 9.3% and 9.4% respectively of all samples, mostly concomitantly. No patient showed any signs of citrate toxicity. Conclusions: We developed a protocol for RCA during CVVH using commercially available replacement fluid that proved safe, flexible and applicable in an Intensive Care Unit (ICU) setting.
The Relationship between Carotid and Coronary Atherosclerotic Damage in Dialysis Patients
Authors: Fabbian F. , Cacici G. , Franceschini L. , Russo G. , Vassanelli C. , Catizone L. , Lupo A. 
Published: January 2018

Background Data relating carotid ultrasound (CU) to atherosclerotic damage evaluated by coronary angiography in hemodialysis patients are scarce. Methods We carried out a cross-sectional study in 33 uremic subjects (age 55±12 years, 22 male, 7 diabetic), who have been on dialysis for 41±48 months (range 2–192). Twenty-two underwent a coronary angiography in order to complete clinical evaluation for inclusion on the kidney transplantation waiting list, and 11 because of coronary artery disease (CAD); Gensini's score was calculated. Intima-media thickness (IMT) and presence of plaques were related to the degree of coronary stenosis and to cardiovascular risk factors. Patients were divided into two groups depending on mean IMT (group 1 IM ≤ 0.9 mm, n=18; group 2 IMT>0.9 mm, n=15). Results Group 2 was older (60±8 vs 50±12 year, p=0.01), had higher frequency of CAD (53 vs 16%, p=0.02) and had higher prevalence of coronary artery stenosis ≥75% in the right (60 vs 22%, p=0.02), left anterior descending (46 vs 16%, p=0.06) and left circumflex coronary arteriers (60 vs 11%, p=0.05) than group 1. IMT was not related to the degree of CAD evaluated by Gensini's score. IMT sensibility and specificity in detecting the presence of hemodynamically significant coronary stenosis were 64% and 68%, respectively. Coronary narrowing was correlated with the degree of stenosis of common, internal and external carotid arteries (Spearman's rank correlation coefficient). During two years of follow-up, six major cardiac events were recorded and they were related to Gensini's score. Conclusions: In uremic patients, ultrasonographic evaluation of carotid arteries is a simple, non-invasive examination that could be a helpful tool in detecting coronary atherosclerotic damage, but IMT does not appear to add more information regarding risk stratification of CAD. (Int J Artif Organs 2007; 30: 315–20)
Prevalence and Correlates of Anemia and Uncontrolled Anemia in Chronic Hemodialysis Patients – The Campania Dialysis Registry
Authors: Di Iorio B. , Cirillo M. , Bellizzi V. , Stellato D. , De Santo N. G. ,   Campania Dialysis Registry Research Group, Aquino A , Anastasio P , Barchiesi S , Bonanno D , Buccino A , Cappabianca F , Cesaro A , Cestaro R , Chiuchiolo L , Chiuchiolo L , Ciaccia L , Cicchella T , Cillo N , Cioffi M , Cirillo E , Confessore N , Costanzo R , D'Apice L , De Felice E , Delgado G , De Luca M , De Luca P , De Luna V , De Maio A , De Pascale C , Della Volpe L , De Simone V , De Simone W , Di Benedetto A , Di Costanzo L , Di Donato R , Di Serafino A , Fabozzi GM , Fiorentino P , Fragetta G , Fumante M , Galise A , Giangrande C , Giobbe A , Gnasso A , Granato P , Guastaferro P , Iacono G , Iandolo R , Iengo G , Lamberti C , La Verde A , Liccardo D , Maddalena L , Mancini L , Manfreda L , Mari R , Marinelli G , Marinelli G , Martignetti V , Mascolini N , Maurodopoulos C , Migliorati M , Memoli M , Milone A , Milone D , Monaco G , Monteleone E , Natale G , Oggero AR , Pavese F , Petrelli P , Pizzola AR , Raucci B , Rubino R , Salvati G , Santoro D , Saviano C , Savignano M , Sforza C , Spitali L , Staulo P , Stellato D , Taddeo U , Terracciano V , Tomasino G , Tramontano P , Veniero P , Ventre M , Verrillo E , Violante B , Vitiello P , Viola G 
Published: January 2018

Background This study investigated prevalence and correlates of anemia and uncontrolled anemia in chronic hemodialysis patients. Methods A cross-sectional analysis was performed on registry data for 2,746 chronic (<6 months) hemodialysis patients aged 25–84. Data collection included years of dialysis, hours of dialysis/wk, disease causing hemodialysis, body mass index (BMI), erythropoietin (EPO) treatment, hemoglobin, markers of viral hepatitis, serum albumin, calcium, and phosphorus. Results Prevalence was 88.7% for anemia (hemoglobin <11 g/100 mL and EPO treatment at any Hb level), 39.4% for uncontrolled anemia (hemoglobin<11 g/100 mL). Gender, years of dialysis, hereditary cystic kidney disease (HCKD), and low BMI (<24 kg/m2) were independent correlates of anemia (P<0.001). Gender, HCKD, low BMI, serum albumin and calcium were independent correlates of uncontrolled anemia (P<0.05). An interaction was found between age (not correlated with anemia and uncontrolled anemia) and the association of gender with uncontrolled anemia (P<0.05). EPO doses were higher in patients with high prevalence of uncontrolled anemia than in patients with low prevalence (i.e., women vs men, other diseases vs HCKD, low vs not-low BMI, P<0.01). Gender, years of dialysis, HCKD, BMI, serum albumin, and calcium were independent correlates of the hemoglobin/EPO dose ratio in patients on EPO treatment (P<0.05). Conclusion Anemia and uncontrolled anemia are more frequent in hemodialysis patients with short-term dialysis, diseases other than HCKD, low BMI, and female gender. Gender effect was lower in elderly patients. Uncontrolled anemia was also associated with low serum albumin and calcium, suggesting that these parameters are indices of EPO resistance.
Enhancement of Viability of Muscle Precursor Cells on 3D Scaffold in a Perfusion Bioreactor
Authors: Cimetta E. , Flaibani M. , Mella M. , Serena E. , Boldrin L. , De Coppi P. , Elvassore N. 
Published: January 2018

The aim of this study was to develop a methodology for the in vitro expansion of skeletal-muscle precursor cells (SMPC) in a three-dimensional (3D) environment in order to fabricate a cellularized artificial graft characterized by high density of viable cells and uniform cell distribution over the entire 3D domain. Cell seeding and culture within 3D porous scaffolds by conventional static techniques can lead to a uniform cell distribution only on the scaffold surface, whereas dynamic culture systems have the potential of allowing a uniform growth of SMPCs within the entire scaffold structure. In this work, we designed and developed a perfusion bioreactor able to ensure long-term culture conditions and uniform flow of medium through 3D collagen sponges. A mathematical model to assist the design of the experimental setup and of the operative conditions was developed. The effects of dynamic vs static culture in terms of cell viability and spatial distribution within 3D collagen scaffolds were evaluated at 1, 4 and 7 days and for different flow rates of 1, 2, 3.5 and 4.5 ml/min using C2C12 muscle cell line and SMPCs derived from satellite cells. C2C12 cells, after 7 days of culture in our bioreactor, perfused applying a 3.5 ml/min flow rate, showed a higher viability resulting in a three-fold increase when compared with the same parameter evaluated for cultures kept under static conditions. In addition, dynamic culture resulted in a more uniform 3D cell distribution. The 3.5 ml/min flow rate in the bioreactor was also applied to satellite cell-derived SMPCs cultured on 3D collagen scaffolds. The dynamic culture conditions improved cell viability leading to higher cell density and uniform distribution throughout the entire 3D collagen sponge for both C2C12 and satellite cells.
Fluid Balance Error in Continuous Renal Replacement Therapy: A Technical Note
Authors: Bagshaw S. M. , Baldwin I. , Fealy N. , Bellomo R. 
Published: January 2018

Background. The reliability and safety of continuous renal replacement therapy (CRRT) machines have improved, yet there still remains the potential for fluid balance errors to occur during treatment. Methods. In vitro testing of two Kimal Hygieia CRRT machines (Plus and Ultima) was performed. Normal saline to simulate the blood circuit and standard bicarbonate-based fluid for replacement were used. All tests were performed in CVVH mode at four ultrafiltration (UF) rates. The testing was based on creation of a voluntary fluid balance error by clamping the line that fills the replacement fluid chamber to stop flow to the (simulated) patient. The time to alarms and fluid balance errors were recorded. The alarms were overridden and the accumulated fluid balance error allowed by the machine was determined. Results. The alarm occurred approximately 1 minute after the replacement fluid line was clamped at all UF rates. There was no limit to the number of times the alarm could be overridden and the accumulated negative fluid balance was proportional to the prescribed UF rate. After the replacement fluid chamber was allowed to re-fill, the machine attempted to correct the fluid deficit and consistently delivered excess fluid to generate a positive fluid balance error. Conclusions. The Hygieia machines appear designed with appropriate alarm and safety features. However, simulated fluid balance errors raise caution for operators. Clinicians and nurses need to understand the clinical implications of alarm overrides. Fluid balance errors caused by failure to acknowledge and correct replacement fluid failure alarms may cause harm to patients.
Prevention of Dialysis Disequilibrium by use of CVVH
Authors: Bunchman T. E. , Hackbarth R. M. , Maxvold N. J. , Winters J. W. , Barletta G.-M. 
Published: January 2018

Objective. Dialysis disequilibrium occurs due to a rapid shift of osmols when hemodialysis is used in cases of extreme uremia. Continuous veno-venous hemofiltration (CVVH) with citrate anticoagulation may offer a safe method of urea reduction. Design. Retrospective, clinical observation. Setting. Tertiary pediatric intensive care unit and nephrology program. Patients Two males, ages 10 and 12 years of age. Intervention. CVVH with citrate anticoagulation. Results. Three to four day reduction of BUN from 180 mg/dL to 22 mg/dL and from 279 mg/dL to 23 mg/dL. Conclusion. Slow and safe improvement of severe urea, hyperphosphatemia, hypocalcemia, and anemia without untoward side effects.
Circulatory Assist with Centrifugal Pump as a Bridge to Recovery: Mathematical Analysis
Authors: Arpesella G. , Mikus E. , Arabia M. , Loforte A. , Mikus P. M. 
Published: January 2018

Mechanical circulatory support is an essential issue in the management of patients with end-stage cardiac failure. The aim of this study is to evaluate the efficacy of temporary support with a centrifugal blood pump as bridge to heart function recovery or bridge to transplantation. Heart recovery is achieved by improving ventricular mechanical working conditions with proper modifications of preload and afterload. This article assesses the advantages of a novel “cardiac chambers” cannulation setting versus the traditional one, in the case of biventricular or isolated right ventricular failure. The study was conducted using a numerical computer model based on the work by Guyton, Sagawa, Westerhof, and Noordergraaf. Simulation of the planned trials was achieved by changing the model parameters, the pump angular velocity, and the inflow and outflow settings. (Int J Artif Organs 2007; 30: 604–10)
Does the Ventrica Magnetic Vascular Positioner (MVP®) for Coronary Artery Bypass Grafting Significantly alter Local Fluid Dynamics? a Numeric Study
Authors: Morbiducci U. , Lemma M. , Ponzini R. , Boi A. , Bondavalli L. , Antona C. , Montevecchi F.M. , Redaelli A. 
Published: January 2018

Objective Automatic devices have been recently introduced to make the anastomosis procedure quick and efficient when creating a coronary bypass on the beating heart. However, the implantation of these devices could modify the graft configuration, consistently affecting the hemodynamics usually found in the traditional anastomosis. As local fluid dynamics could play a significant role in the onset of vessel wall pathologies, in this article a computational approach was designed to investigate flow patterns in the presence of the Ventrica magnetic vascular positioner (Ventrica MVP®) device. Methods A model of standard hand-sewn anastomosis and of automated magnetic anastomosis were constructed, and the finite volume method was used to simulate in silico realistic graft hemodynamics. Synthetic analytical descriptors - i.e., time-averaged wall shear stress (TAWSS), oscillating shear index (OSI) and helical flow index (HFI) - were calculated and compared for quantitative assessment of the anastomosis geometry hemodynamic performance. Results In this case study, the same most critical region was identified for the 2 models as the one with the lowest TAWSS and the highest OSI (TAWSS=0.229, OSI=0.255 for the hand-sewn anastomosis; TAWSS=0.297, OSI=0.171 for the Ventrica MVP®). However, the shape of the Ventrica MVP® does not induce more critical wall shear stresses, oscillating flow and damped helicity in the graft fluid dynamics, as compared with conventional anastomosis. Conclusions We found that the use of the Ventrica MVP® for the case study under investigation was not associated with more critical fluid dynamics than with conventional hand-sewn anastomosis. Thereby, the device could facilitate beating heart and minimally invasive coronary artery bypass grafting without increasing local hemodynamic-related risks of failure. (Int J Artif Organs 2007; 30: 628–39)
Medicolegal Reflections about a Case of Cardiac Death after Renal Transplantation
Authors: Di Paolo M. , Guidi B. 
Published: January 2018

Cardiovascular disease is the most common cause of death in patients with renal transplant. Acute coronary syndrome due to coronary artery disease, and left ventricular hypertrophy leading to chronic heart failure account for the majority of sudden arrhythmic deaths after transplantation. Furthermore death with functioning graft represents the main cause of graft loss, particularly after the first post-transplantation year. Although cardiovascular disease leads to morbidity and mortality in renal transplant recipients, its pathogenesis is poorly understood. The high incidence of cardiovascular disease in patients after renal transplant is chiefly due to high occurence and accumulation of traditional risk factors before and after transplantation. Hypertension, post-transplant diabetes mellitus and hyperlipidemia increase the risk for cardiovascular events. Also “non traditional” risk factors are associated with cardiovascular disease. Moreover several immunosuppressive drugs interfere with the cardiovascular system. The authors present a case of cardiac death following renal transplant in a patient with history of cardiovascular disease prior transplantation. Initially treated by hemodialysis, after 3 years he received a cadaveric renal transplant. The post-transplantation period was without surgery complications, immunological or infectious, except for a scarce control of blood pressure. A month after the operation, the patient developed thrombophlebitis, plus extra-peritoneal swelling. After ten days in hospital he suddenly died. The aim of the manuscript is to remark on the legal relevance of patient's consensus to transplant. It is necessary to well inform patients of an operation's risks and complications. Furthermore, the exceeding demand with respect to organ availability raises ethical issues about organ allocation. (Int J Artif Organs 2007; 30: 649–55)
Potential Adverse Effects of Replacing High Volume Hemofiltration Exchanges on Electrolyte Balance and Acid-Base Status Using the Current Commercially Available Replacement Solutions in Patients with Acute Renal Failure
Authors: Davenport A. 
Published: January 2018

The original substitution and/or dialysates used for continuous hemofiltration and/or dialysis were either based on peritoneal dialysis fluids, or peritoneal dialysates themselves. Although these fluids have been refined over the years, by changing the anionic base from acetate or racemic d+ l-lactate, to bicarbonate or l-lactate, the fluids remain designed for low volume hourly exchanges. Even at relatively low volume exchanges, the composition of these fluids can affect systemic acid-base balance. Those fluids which contain a higher concentration of lactate with a corresponding lower chloride, predispose to a hypochloremic alkalosis, whereas those with a lower concentration of lactate with a corresponding higher chloride potentially lead to a hyperchloremic acidosis. In addition, cation balance, differs when using the same fluid as a replacement solution, compared to dialysate. In particular, sodium balance is greater for post-dilutional fluid replacement, due to the lower sieving coefficient. More recently, citrate has been introduced as an extracorporeal anticoagulant, and a variety of dialysates/replacement fluids have been developed, due to the difference in citrate clearance between dialysis and convection based extracorporeal circuits. Over the last decade, there has been a general increase in the standard hourly dialysate and exchange volumes used in the management of patients with acute kidney injury, from 1 to 2.5–3 l/h. Indeed, even larger volume exchanges, some 6–8 l/h have been advocated to improve patient outcomes. However, before embarking on such continuous high volume exchanges, a new generation of fluids may need to be developed to prevent acid-base and electrolyte imbalances. (Int J Artif Organs 2008; 31: 3–5)