International Journal of Artificial Organs最新文献

Ventricular assist devices (VADs) are essential for end-stage heart failure patients, but their design must balance hydraulic efficiency and hemocompatibility to minimize blood damage. This study presents a multi-objective optimization framework integrating computational fluid dynamics (CFD), Random Forest Regression (RFR), and Bayesian optimization to improve VAD rotor hemocompatibility. Seven key design parameters (inlet/outlet blade angles, blade count, rotational speed, clearance gap, blade thickness, and rotor length) were optimized using a D-optimal design of experiments. The RFR surrogate model demonstrated superior performance in handling the complex parameter interactions, achieving high predictive accuracy (R² > 0.84 for all hemocompatibility metrics). CFD simulations employing a Carreau-Yasuda blood model and rigorous mesh independence analysis evaluated shear stress distributions, exposure times, hemolysis index (HI), and platelet activation state (PAS). The optimized design achieved 97.24% of blood flow with shear stress <50 Pa, a HI of 0.01%, and PAS of 1 × 10^-6%, representing significant improvements over baseline configurations. While this computational study provides comprehensive parametric insights, future experimental validation is recommended to confirm these findings under physiological conditions. The proposed framework offers a systematic approach for developing high-performance VADs with enhanced hemocompatibility.

Electrocardiogram (ECG) signal classification plays a critical role in diagnosing various cardiac conditions by identifying irregularities in heart rhythms. Despite advancements in the field, existing methodologies often rely on basic techniques that inadequately filter noise, leading to degraded performance and misinterpretation of vital features. This study presents the Spectral-Optimized Cardiac Framework (SOCF) approach to enhance the accuracy of ECG classification through advanced noise filtering, comprehensive feature extraction, efficient feature selection and integration of hybrid modelling techniques. The proposed methodology introduces the ChebWave Mean Refinement Filter (CWMRF) for effective noise reduction and to enhance signal clarity while preserving essential characteristics. In feature extraction, the Spectral Essence Extractor (SEE) captures both basic and high order features, providing deeper insights into ECG signals. Additionally, the Deep Blue Particle Optimizer (DBPO) efficiently identify relevant features while mitigating the risk of overfitting. Furthermore, the hybrid architecture of Convolutional neural network (CNN) and long short-term memory (LSTM) enable the model to effectively capture both spatial and temporal dependencies, thereby improving classification accuracy. To optimize performance, the Aquila Optimizer enhances the convergence speed and model efficiency by employing diverse search strategies inspired by the hunting behavior of Aquila bird. By integrating these advanced techniques, the SOCF achieved impressive results on the MIT-BIH dataset and PTB dataset with an accuracy of 99.6% and 99.68%, precision of 99.4% and 99.44%, recall of 99.5% and 99.51%, and F1 score of 99.2% and 99.49%, which significantly improves the robustness and reliability of ECG signal classification, ultimately providing more accurate clinical insights and better patient outcomes.

Background: The left ventricular assist device (LVAD) goes through a counterclockwise dynamic characteristic loop under heart-pump coupled working state. However, few studies have investigated the underlying physical mechanisms from the flow field perspective.

Method: Computational fluid dynamic (CFD) methods are used for unsteady flow field simulations and hemolytic possibility predictions in one cardiac cycle. The pressure boundary conditions are set based on the prior in vitro experiment.

Results: Flow blockage started at the inlet guide vanes (IGVs) and affected the downstream flow field at early systole, and occurred mainly at the outlet guide vanes (OGVs) during diastole. At a typical flow-rate, the residence time in IGVs accounted for 42.55% of all parts during systole whereas only 18.75% during diastole.

Conclusion: The dynamic characteristic loop is closely related to the movement of vortices within the pump, as the low-speed vortices failing to respond in time to the changes in boundary conditions. An increased likelihood of adverse events is anticipated at early systole.

Significance: This study reveals the physical mechanisms underlying the flow field changes within the pump during coupled working. The detailed hemolytic analysis at different cardiac events helps the subsequent real-time intelligent pump adjust strategies.

In vitro hemolysis, assessed through the normalized hemolysis index (NIH) and the modified hemolysis index (MIH), serves as a critical indicator of the hemocompatibility of rotary blood pump designs. Despite the widespread application of the American Society for Testing and Materials (ASTM) standards in conducting in vitro hemolysis testing, the NIH and MIH values for a specific pump can vary considerably across different research centers or even between individual tests. To reduce this variability and facilitate global comparisons of hemolysis levels, this article reviews the underlying theory, existing literature, and empirical knowledge, alongside the practices implemented at the authors' facility. The reviewed factors influencing the variability of the hemolysis index encompass the selection of blood donor species, the source and method of blood withdrawal, blood handling and regulation, the choice of anticoagulants, the configuration of the circulation loop, local flow conditions within the loop, and the measurement of plasma-free hemoglobin. Detailed justifications and recommendations for each factor within a standardized testing framework are provided. The three primary factors that may yield more reliable and universally comparable results include enhancing clinical relevance, minimizing additional blood damage, and preventing blood clot formation. By regulating the associated parameters, it is possible to minimize measurement variance even in the absence of a predictive device.

Objective: This study aimed to investigate the relationship between the changes of serum indoxyl sulfate (IS) concentration, Klotho protein level, and cardiovascular complications in patients with chronic kidney disease (CKD) stage 3-5.

Methods: A total of 108 patients with CKD stage 3-5 were selected. They were divided into three groups: CKD stage 3-4 group, CKD stage 5 non-dialysis group, and CKD stage 5 dialysis group. Echocardiography was used to measure left ventricular diameter (LVD), interventricular septal thickness (IVS), left ventricular posterior wall thickness (LVPW), and calcification.

Results: there was no significant difference in age between the healthy control group and the patients with CKD stage 3-5 (p > 0.05). Compared to healthy controls, serum creatinine, serum phosphorus, iPTH, serum IS, left ventricular diameter, interventricular septum thickness, left ventricular septal wall thickness, and the proportion of valve calcification increased gradually, while serum calcium and Klotho protein decreased The level of serum IS was positively correlated with the level of LVD, IVS, and valve calcification in CKD patients, while the level of serum Klotho protein was negatively correlated with the level of IVS and valve calcification in CKD patients.

Conclusion: In patients with chronic kidney disease (CKD), the incidence of cardiovascular complications is significantly higher than in the general population. The increase of serum IS level and the decrease of serum Klotho protein level are closely related to cardiac injury, it IS suggested that serum IS level and Klotho protein level may be a good index for monitoring cardiovascular injury in CKD patients.

Background: There has been an exponential increase in the utilization of temporary mechanical support devices for bridging Status 2 heart transplant candidates. The aim of our study is to determine outcomes in dual organ heart/kidney recipients for patients bridged with an Impella 5.5 versus IABP.

Methods: We evaluated the UNOS database and analyzed Status 2 patients who underwent dual organ heart/kidney transplantation after being bridged with an Impella 5.5 or IABP from October 2019 (time of Impella 5.5 FDA approval) until March 2024.

Results: A total of 457 patients who underwent Heart/Kidney transplant (HKT) were identified, of which 73% (334/457) were bridged with an IABP and 27% (123/457) with an Impella 5.5. Within the IABP cohort, 37% (122/334) were on dialysis pre-transplant compared to 43% (53/123) in the Impella group (p = 0.409). Patients in the Impella group had worse functional status, liver function, and filling pressures. There was no difference in the need for dialysis post-transplant (32% vs 29%, p = 0.613). Survival at 30, 180, and 360 days and the rates of primary graft dysfunction, acute, and chronic rejection were similar between the two groups.

Conclusion: Both IABP and Impella appear to be safe for bridging dual organ heart and kidney transplant candidates, with comparable post-transplant heart and kidney graft function, complications, and survival up to 2 years. Patients receiving Impella 5.5 appear to be sicker and as a result, this percutaneous temporary mechanical circulatory support device may confer some advantages, especially for patients with dual organ failure who undergo transplantation.

Flatfoot is a very common condition that alters gait mechanics and is usually accompanied by pain. In this current study, two types of custom-made insoles using polyethylene and silicon, respectively, were designed to help alleviate this condition. Such insoles are tested for their functionality using advanced 3D printing and finite element analysis. Tests were conducted at body weights of 60, 80, 100, and 120 kg. Results indicated that silicone insoles outperformed the others by effecting a better redistribution of pressure with higher magnitudes of strain and stress. Specifically, silicon had strain values between 1.44 × 10^-7 and 2.88 × 10^-7, much lower than polyethylene's 5.92 × 10^-5-1.18 × 10^-4. Whereby, silicon would withstand stress levels to about 47,058 Pa, while polyethylene would do so at 31,932 Pa, making it more resilient under higher loads. Further validation through kinematic analysis proved that silicon insoles enhance the symmetry of walk and disperses the concentration of pressures of the feet, therefore providing more comfort and support during locomotion. These results suggest that silicon insoles offer significant benefits for managing flatfoot, paving the way for future innovations in personalized orthopedic footwear.

Background: The concentration of bicarbonate in dialysis fluid (Dbic) that regulates acid-base balance in dialyzed patients is individually adjusted and may be modified during a hemodialysis session. We evaluated the impact of modifications of Dbic on plasma electrolytes.

Methods: Two midweek hemodialysis sessions were monitored in 25 anuric, prevalent hemodialysis patients (67.9 ± 9.3 years old, 32% females). During the first session (treatment A) Dbic was constant at 33.6 ± 1.7 mmol/L, while for the second week (treatment B) it was on average 30.8 ± 2.3 mmol/L for the initial 2 h and 34.0 ± 2.5 mmol/L for the last 2 h.

Results: During treatments A and B plasma bicarbonate (Pbic) increased during the sessions and was lower for treatment B than A at 60 and 120 min of dialysis. Plasma chloride decreased during treatments A and B and was significantly higher at 60 and 120 min of dialysis in treatment B than in treatment A. An increase of plasma calcium was observed during both treatments and it was higher for treatment B than A at 60 and 120 min. A similar profile of plasma sodium and potassium was observed during treatments A and B. The difference in Pbic correlated positively, whereas the differences in plasma chloride and calcium correlated negatively, with the difference in Dbic between treatments B and A.

Conclusion: Modifications of dialysate bicarbonate may influence the concentrations of some other electrolytes in plasma; for each percent of Dbic increase one may expect -0.27 and -0.16% change in plasma chloride and calcium, respectively.

Introduction: Hemodialysis (HD) represents a necessary medical intervention for patients with end stage kidney disease (ESKD) with a high carbon footprint that significantly consumes natural resources (i.e. water). Reduction of dialysate flow rate is one strategy that directly targets water waste during HD.

Methods: A retrospective multicenter, observational study was conducted over 12 months in patients with AKI-D and ESKD to evaluate treatments with mid-range dialysate flow rates set at Qd 300 mL/min (Green HD) using the Tablo^® HD System (Outset Medical) versus flow rates ⩾Qd 500 mL/min (Conventional systems).

Results: One thousand one hundred ninety-five treatments were performed in 433 patients using Green HD (Qd = 300 mL/min, n = 575) and Conventional systems (Qd ⩾500 mL/min, n = 620). Mean Qd for Green HD was 300.0 ± 0.0 and mean Qd for the Conventional systems was 686.6 ± 88.3 mL/min. Mean blood flow rates were significantly lower among patients treated with Green HD. Reductions in TACurea and post dialysis serum potassium were similar between the two groups. Estimates for resource utilization were lower using Green HD compared to Conventional systems.

Conclusion: These findings support that higher dialysate flow rates using Conventional systems yield minimal if any benefit in small solute clearance compared to mid-range flow rates. Green HD using the Tablo^® HD System results in comparable benefits in ESKD patients with significant conservation of water resources.

Background: Quality of life (QoL) serves as a critical metric for evaluating the well-being of individuals undergoing hemodialysis. This study sought to identify the factors that impact QoL in hemodialysis patients using the Kidney Disease Quality of Life-36 (KDQOL-36) questionnaire.

Methods: A cross-sectional study was conducted with 74 hemodialysis patients at our institution between August 2021 and August 2024. Participants completed the KDQOL-36, Hamilton Depression Scale (HAMD-24), and Social Support Rating Scale (SSRS). Demographic and clinical variables were collected. Statistical methods, including descriptive analysis, correlation testing, and multiple regression, were used to determine factors linked to KDQOL-36 outcomes.

Results: The average age of participants was 57.59 ± 13.61 years, with a median dialysis duration of 36.0 (12.0-76.5) months. The subscale scores on the KDQOL-36 were as follows: Symptoms/Problems List (S): median 78.1 (IQR = 65.6-87.5), Effects of Kidney Disease (E): median 59.4 (IQR = 43.8-71.9), Burden of Kidney Disease (B): median 43.8 (IQR = 31.3-62.5), SF-12 Physical Component Summary (PCS): mean 41.35 ± 8.49, and SF-12 Mental Component Summary (MCS): mean 46.73 ± 11.66. Regression analysis identified age, dialysis duration, hemoglobin levels, depression severity, and social support as key predictors of QoL across the KDQOL-36 subscales.

Conclusion: Several factors contribute to the QoL of hemodialysis patients. Interventions addressing modifiable factors such as anemia, depression, and social support enhancement could potentially improve the overall QoL for this patient group.