RESUMEN

The present analysis deals with the entropy analysis of the blood flow through an anisotropically tapered arteries under the suspension of magnetic Zinc-oxide (ZnO) nanoparticles (NPs). The Jeffrey fluid model is contemplated as blood that is electrically conducting and incompressible. The lubrication approach is used for the mathematical modeling. The second law of thermodynamics is used to examine the entropy generation. The exact solutions are obtained against velocity and temperature profile with the use of computational software. The results for Entropy, Velocity, Bejan number, temperature profile, and impedance profile are discussed by plotting the graphs. ZnO-NPs have promising applications in biomedical engineering due to its low toxicity, economically reliable, and excellent biocompatibility. ZnO-NPs also emerged in medicine i.e., antibacterial and anticancer activity, and also beneficial in antidiabetic treatment. The monitoring of the blood temperature in the case of the tapered artery has supreme importance in controlling the temperature of blood in the living environment. The presence of a magnetic field is advantageous to manage and control the blood motion at different temperatures. The present outcomes are enriched to give valuable information for the research scientists in the field biomedical science, who are looking to examine the blood flow with stenosis conditions and also beneficial in treating multiple diseases.

RESUMEN

Two-dimensional rheological laminar hemodynamics through a diseased tapered artery with a mild stenosis present is simulated theoretically and computationally. The effect of different metallic nanoparticles homogeneously suspended in the blood is considered, motivated by drug delivery (pharmacology) applications. The Eringen micropolar model has been discussed for hemorheological characteristics in the whole arterial region. The conservation equations for mass, linear momentum, angular momentum (micro-rotation), and energy and nanoparticle species are normalized by employing suitable non-dimensional variables. The transformed equations are solved numerically subject to physically appropriate boundary conditions using the finite element method with the variational formulation scheme available in the FreeFEM++ code. A good correlation is achieved between the FreeFEM++ computations and existing results. The effect of selected parameters (taper angle, Prandtl number, Womersley parameter, pulsatile constants, and volumetric concentration) on velocity, temperature, and micro-rotational (Eringen angular) velocity has been calculated for a stenosed arterial segment. Wall shear stress, volumetric flow rate, and hemodynamic impedance of blood flow are also computed. Colour contours and graphs are employed to visualize the simulated blood flow characteristics. It is observed that by increasing Prandtl number (Pr), the micro-rotational velocity decreases i.e., microelement (blood cell) spin is suppressed. Wall shear stress decreases with the increment in pulsatile parameters (B and e), whereas linear velocity increases with a decrement in these parameters. Furthermore, the velocity decreases in the tapered region with elevation in the Womersley parameter (α). The simulations are relevant to transport phenomena in pharmacology and nano-drug targeted delivery in hematology.

Asunto(s)

RESUMEN

The natural tapering of coronary arteries often creates a dilemma for optimal balloon sizing during stenting. The influence of different balloon types, namely, a tapered balloon and a conventional cylindrical balloon, on the mechanical performance of the stent as well as arterial mechanics was investigated via the finite element method. Stent free-expansion and stent deployment in a stenotic tapered artery were investigated numerically. The biomechanical behavior of the two balloon types was compared in terms of stent foreshortening, stent deformation, stent stress distribution, and arterial wall stress distribution. Results indicate that balloon types affect the transient behavior of the stent and the arterial mechanics. Specifically, a tapered balloon could maintain the natural tapering of the coronary artery after stent expansion. In contrast to a cylindrical balloon, tapered balloon also mitigated the foreshortening of the stent (7.69%) as well as the stress concentration in the stent and artery (8.61% and 4.17%, respectively). Hence, tapered balloons should be used in tapered arteries as they may result in low risk of artery injury. This study might provide insights for improved balloon choice and presurgical planning.

Asunto(s)

RESUMEN

Stenting has achieved great success in treating cardiovascular diseases due to its high efficiency and minimal invasiveness. However, fatigue of stents severely limits its long-term outcome. In this article, finite element method was adopted to study the effects of arterial tapering and stent material on the fatigue performance of stents. A series of tapered vessels with different taper levels and two sets of stents with different materials were modeled. The Goodman diagram was used to evaluate the fatigue resistance of stents. Results showed that the fatigue resistance of stents can be extremely improved by simply changing stent material. In addition, the taper of the arteries had an important influence on the fatigue resistance of the stent. The fatigue life of the stent will be shortened with the increase of the arterial taper. The method that predicted stent fatigue life in tapered vessels can help clinicians select stents that are more suitable for tapered vessels and help stent engineers design stents that are more resistant to fatigue.

Asunto(s)

RESUMEN

BACKGROUND: Vascular stenting has been widely used to treat vessel stenosis. However, long-term successes of the procedure are often compromised by late stent thrombosis (ST) and in-stent restenosis (ISR), especially in tapered arteries. OBJECTIVE: The aim of this study was to choose a reasonable expansion strategy for tapered arteries. METHODS: A balloon-expandable coronary stent deployment in a tapered vessel was numerically studied fol-lowing three strategies: (i) selecting the proximal diameter of the tapered vessel as the reference diameter to expand the stent, (ii) selecting the middle diameter of the tapered vessel as the reference diameter to expand the stent, and (iii) selecting the distal diameter of the tapered vessel as the reference diameter to expand the stent. RESULTS: Computational results showed that the first expansion strategy resulted in the maximum vessel stress and the best stent apposition, while the third strategy resulted in the minimal vessel stress and the worst stent appo-sition. Meanwhile, the second expansion strategy achieved a trade-off between the first and third strategies, leading to acceptable vessel stress and stent apposition. CONCLUSIONS: The second expansion strategy is the most reasonable choice for tapered vessels, and it should be considered when implanting a stent.

Asunto(s)

RESUMEN

BACKGROUND AND OBJECTIVES: In the present article, I have studied the blood flow of a Walter's B fluid through a tapered artery with a stenosis. The problem is modeled in cylindrical coordinates system. METHODS RESULTS CONCLUSIONS: The analytical solutions have been carried out using regular perturbation method by taking α as perturbation parameter. The expressions for velocity, resistance impedance, wall shear stress and shearing stress at the stenosis throat have been evaluated. The graphical results of different types of tapered arteries (i.e. converging tapering, diverging tapering, non-tapered artery) have been examined for different parameters of interest.

Asunto(s)