Cardiovascular Engineering and Technology最新文献

Purpose: The cross-limb (CL) technique is a commonly used endovascular treatment for addressing unfavorable anatomical features in patients with abdominal aortic aneurysm (AAA). The configuration of CL stent-graft plays a critical role in determining the postoperative hemodynamic properties and physiological behaviors, which ultimately impact the efficacy and safety of endovascular AAA treatment. This study aims to investigate the relationship between hemodynamics and CL stent-graft configuration from a hemodynamic perspective.

Methods: Five distinct geometric models of cross-limb (CL) stent-graft configurations were constructed by optimizing the real clinical computed tomography angiography (CTA) data. These models varied in main body lengths and cross angles and were used to perform numerical simulations to analyze various hemodynamic parameters. Flow pattern, distribution of wall shear stress (WSS)-related parameters, localized normalized helicity (LNH), pressure drop, and the displacement force of all models were examined in this paper.

Results: In patient-specific cases, helical flow and WSS increase with the main body. However, it also generated secondary flow in localized areas, leading to increased oscillation in the WSS direction. Notably, increasing the stent graft's main body length or decreasing the cross angle reduced the displacement force exerted on the stent-graft. Reducing the cross angle did not significantly alter the hemodynamic characteristics.

Conclusion: In the clinical practice of CL deployment, it is crucial to carefully consider the stent-graft configuration and the patient specific to achieve optimal postoperative outcomes. This study provides valuable insights for guiding stent selection and treatment planning in patients with abdominal aortic aneurysm undergoing CL techniques, from a hemodynamic perspective.

For recent decades, cardiac diseases have been the leading cause of death and morbidity worldwide. Despite significant achievements in their management, profound understanding of disease progression is limited. The lack of biologically relevant and robust preclinical disease models that truly grasp the molecular underpinnings of cardiac disease and its pathophysiology attributes to this stagnation, as well as the insufficiency of platforms that effectively explore novel therapeutic avenues. The area of fundamental and translational cardiac research has therefore gained wide interest of scientists in the clinical field, while the landscape has rapidly evolved towards an elaborate array of research modalities, characterized by diverse and distinctive traits. As a consequence, current literature lacks an intelligible and complete overview aimed at clinical scientists that focuses on selecting the optimal platform for translational research questions. In this review, we present an elaborate overview of current in vitro, ex vivo, in vivo and in silico platforms that model cardiac health and disease, delineating their main benefits and drawbacks, innovative prospects, and foremost fields of application in the scope of clinical research incentives.

Purpose: Intravascular endoscopy can aid in the diagnosis of coronary atherosclerosis by providing direct color images of coronary plaques. The procedure requires a blood-free optical path between the catheter and plaque, and achieving clearance safely remains an engineering challenge. In this study, we investigate the hemodynamics of saline flushing in partially occluded coronary arteries to advance the development of intravascular forward-imaging catheters that do not require balloon occlusion.

Methods: In-vitro experiments and CFD simulations are used to quantify the influence of plaque size, catheter stand-off distance, saline injection flowrate, and injection orientation on the time required to achieve blood clearance.

Results: Experiments and simulation of saline injection from a dual-lumen catheter demonstrated that flushing times increase both as injection flow rate (Reynolds number) decreases and as the catheter moves distally away from the plaque. CFD simulations demonstrated that successful flushing was achieved regardless of lumen axial orientation in a 95% occluded artery. Flushing time was also found to increase as plaque size decreases for a set injection flowrate, and a lower limit for injection flowrate was found to exist for each plaques size, below which clearance was not achieved. For the three occlusion sizes investigated (90, 95, 97% by area), successful occlusion was achieved in less than 1.2 s. Investigation of the pressure fields developed during injection, highlight that rapid clearance can be achieved while keeping the arterial overpressure to < 1 mmHg.

Conclusions: A dual lumen saline injection catheter was shown to produce clearance safely and effectively in models of partially occluded coronary arteries. Clearance was achieved across a range of engineering and clinical parameters without the use of a balloon occlusion, providing development guideposts for a fluid injection system in forward-imaging coronary endoscopes.

Purpose: The valve-sparing aortic root replacement (VSARR) procedure was developed to preserve the aortic valve apparatus to replace aneurysmal aortic roots with synthetic grafts and to eliminate associated aortic regurgitation (AR). However, residual post-repair AR is not uncommon and has been found to be associated with recurrent AR and future reoperation.

Methods: We designed and manufactured a 3D-printed, external adjustable symmetrically extensible (EASE) aortic annuloplasty ring that can symmetrically reduce the aortic annulus diameter via a radial constriction, compliant mechanism. An ex vivo porcine VSARR model with annular dilation and AR was developed (n = 4) and used for hemodynamic, echocardiography, and high-speed videography data collection.

Results: After ring annuloplasty repair using the EASE aortic ring, the regurgitant fraction decreased from 23.6 ± 6.9% from the VSARR model to 7.4 ± 5.6% (p = 0.05), which was similar to that measured from baseline with a regurgitant fraction of 10.2 ± 3.9% (p = 0.34). The leaflet coaptation height after annuloplasty repair also significantly increased from that measured in VSARR model (0.4 ± 0.1 cm) to 0.9 ± 0.1 cm (p = 0.0004), a level similar to that measured in baseline (1.1 ± 0.1 cm, p = 0.28).

Conclusion: Using an ex vivo VSARR model, the EASE ring successfully reduced AR by reducing the annular diameter and improving leaflet coaptation. With its broad applicability and ease of use, this device has the potential to have a significant impact on patients suffering worldwide from AR due to root aneurysms.

Purpose: The electrokinetic process for streaming fluids in magnetic environments is emerging due to its immense applications in medical and biochemical industrial domains. In this context, our proposed model seeks to inquire into the hemodynamic characteristics of electro-magnetized blood blended with trihybrid nanoparticles circulation induced by electro-osmotic forces in an endoscopic charged arterial annular indented tract. This steaming model also invokes the consequences of variable Lorentz attractive force, buoyancy force, heat source, viscous and Joule warming, arterial wall properties, and sliding phenomena for featuring more realistic problems in blood flows. Different shapes of suspended trihybrid nanoparticles, such as spheres, bricks, cylinders, and platelets, are included in the model formation. Electro-magnetized modified hybrid nano-blood is an electro-conductive solution comprising blood as base fluid and magnetized trihybrid nanoparticles (copper, gold, and alumina).

Methods: Closed-form solution in terms of Bessel's functions is gotten for electro-osmotic potential due to the electric double layer (EDL). The homotopy perturbation methodology is implemented in order to track down the convergent series solutions of non-linear coupled flow equations being elicited. The physical attributes of distinct evolving parameters on the different dimensionless hemodynamic profiles and quantities of interest are elucidated evocatively via a sort of graphs and charts.

Results: The ancillary outcomes proved that the Debye-Hückel parameter and Helmholtz-Smoluchowski velocity have a dual impact on the ionized bloodstream. The bloodstream rapidity is alleviated/boosted for the assisting/opposing electroosmosis process. Cooling of ionized blood in the endoscopic arterial conduit is achieved with lower Hartmann numbers. Copper-gold-alumina/blood exhibits a superior heat transmission rate across the arterial wall than copper-gold-blood, copper-blood, and pure blood. Additionally, the contour topology for the bloodstream in the flow domain is briefly elaborated. The contour distribution is significantly amended due to the variant of the Debye-Hückel parameter.

Conclusion: The model's new findings may be invaluable in electro-magneto-endoscopic operation, electro-magneto-treatment for cancer, surgical process, etc.

Purpose: Piezoelectric energy harvesters (PEH) for cardiac pacemakers typically use animal models to assess the performance of the PEH. However, if considering multiple designs, the use of animal models and prototyping increases costs and time. To reduce the use of animal models in research for pacemaker energy harvesting applications, this study investigates the motion of a pacemaker lead wire (PLW) in vivo using fluoroscopy imaging to quantify the position and displacements as a function of time, such that the data can be used in computer simulations.

Methods: The proposed technique uses fluoroscopy imaging video data of a dual chamber pacemaker implanted in a patient, and image processing allows for the motion of the PLW captured. The motion is discretized into nodes for ease of implementation in finite element software. FEA simulation is presented using a piezoelectric energy harvester design integrated in the lead wire, and the energy output is predicted by finite element computer simulation.

Results: A 2-dimensional analysis is conducted with the fluoroscopy imaging video data to characterize the PLW motion and results show close agreement with literature values. Simulations with an energy harvesting circuit using the nodal position and displacement data shows that a PEH integrated in the PLW can generate a direct current voltage of 1.12 V and power output of 0.125 μW, potentially extending the battery life of pacemakers by 0.75-1 years.

Conclusions: The results suggest that fluoroscopy imaging data can be effective in evaluating PEH designs rather than using animal models, saving time and costs.

Abstract

In clinical rhythmology, intracardiac bipolar electrograms (EGMs) play a critical role in investigating the triggers and substrates inducing and perpetuating atrial fibrillation (AF). However, the interpretation of bipolar EGMs is ambiguous due to several aspects of electrodes, mapping algorithms and wave propagation dynamics, so it requires several variables to describe the effects of these uncertainties on EGM analysis. In this narrative review, we critically evaluate the potential impact of such uncertainties on the design of cardiac mapping tools on AF-related substrate characterization. Literature suggest uncertainties are due to several variables, including the wave propagation vector, the wave's incidence angle, inter-electrode spacing, electrode size and shape, and tissue contact. The preprocessing of the EGM signals and mapping density will impact the electro-anatomical representation and the features extracted from the local electrical activities. The superposition of multiple waves further complicates EGM interpretation. The inclusion of these uncertainties is a nontrivial problem but their consideration will yield a better interpretation of the intra-atrial dynamics in local activation patterns. From a translational perspective, this review provides a concise but complete overview of the critical variables for developing more precise cardiac mapping tools.

Purpose: The electrocardiogram signal (ECG) presents a fundamental source of information to consider for the diagnosis of a heart condition. Given its low-frequency features, this signal is quite susceptible to various noise and interference sources. This paper presents an improved hybrid approach to ECG signal denoising based on the DWT and the ADTF methods.

Methods: The proposed improvements consist of integrating an adaptive [Formula: see text] parameter into the ADTF approach, combining a soft thresholding ADTF-based process with the DWT details, along with employing the mean filter to handle the baseline wandering noise. Furthermore, the proposed approach incorporates several denoising measures based on various proposed noise features, which have also been introduced in this approach. Several real noises collected from the Noise Stress Test Database (NSTDB), as well as several synthetic noises at different SNR levels, are proposed to ensure a thorough assessment of the proposed method's performance.

Results: The evaluation focuses on the SN Rimp, PRD, and MSE parameters, as well as the SINAD parameter as a diagnostic distortion measurement. Furthermore, a time complexity evaluation is proposed. The proposed approach demonstrated promising results compared to a recent hybridization of the DWT and ADTF methods, as well as recently published ECG signal denoising-based approaches in various real and synthetic noise cases using different statistical evaluation metrics.

Conclusion: In the vast majority of the study cases, the proposed approach outperforms the compared methods in terms of statistical results for real and synthetic noises. Furthermore, compared to these methods, it provides a fairly low time complexity. This is consistent with the ambition of embedding this approach in low-cost hardware architectures.

Purpose: Pulsed-field ablation (PFA) has attracted attention for the treatment of atrial fibrillation. This study aimed to further explore the relationship between the transmembrane voltage, pore radius and the intensity and duration of pulsed electric fields, which are closely related to the formation of irreversible electroporation. The different mechanisms of microsecond and nanosecond pulses acting on cardiomyocyte cellular and nuclear membranes were studied.

Methods: A 3-D cardiomyocyte model with a nucleus was constructed to simulate the process of electroporation in cells under an electric field. Cell membrane electroporation was used to simulate the effect of different pulse parameters on the process of electroporation.

Results: Under a single pulse with a field strength of 1 kV/cm and width of 100 μs, the transmembrane potential (TMP) of the cell membrane reached 1.33 V, and the pore density and conductivity increased rapidly. The maximum pore radius of the cell membrane was 43.4 nm, and the electroporation area accounted for 4.6% of the total cell membrane area. The number of pores was positively correlated with the electric field intensity when the cell was exposed to electric fields of 0.5 to 6 kV/cm. Under a nanosecond pulse, the TMP of the nuclear and cell membranes exceeded 1 V after exposure to electric fields with strengths of 4 and 5 kV/cm, respectively.

Conclusion: This study simulated the electroporation process of cardiomyocyte, and provides a basis for the selection of parameters for the application of PFA for application toward arrhythmias.