The finite analysis method is able to provide insights into the behaviour of the over pressured model (myocardium). In the overloaded model the high stresses and strains were observed on the septal wall. The bi-ventricular model was shown to provide useful information relating to the over pressured ventricle. The possible heart dysfunction may be attributable to high stress and strain in the over pressured heart.
The physiological basis of the right ventricle diastolic function is not well studied. In most heart failure, heart transplantation remains the first choice with survival ranges between 40% and 50%. It is known that heart transplantation lacks donors and therefore, there is a need to search for new surgical techniques for heart failure prevention. This study utilized the finite elment method to study the structural behavior of heart wall under severe pressures. In this study the effect RV filling during over-pressurised RV using bi-ventricular model has been studied using finite element modeling (FEM). Cardiovascular disease (CVD) is the leading cause of death in low-income and middle-income countries. The right ventricle (RV) dysfunction is understood to have an impact on the performance of the left ventricle (LV) but the mechanisms remain poorly understood. Finite strain analyses of bi-ventricular model provide important information on the heart function. The passive myocardium was modelled as a nearly incompressible, hyperelastic, transversely isotropic material. Biventricular geometries of healthy and infarcted rat hearts reconstructed from magnetic resonance images were imported in Abaqus©. In simulating the passive filling of the healthy condition of the rat heart, the inner walls of the LV and RV the pressures of 4.8 kPa and 0.0098 kPa were applied respectively. The average circumferential strain was found to be 0.138 and 0.100 on the endocardium of the over-pressured and healthy model respectively. The high stresses and strains on the over-loaded model were observed.
Cardiovascular diseases account for one third of all deaths worldwide, more than 33% of which are related to ischemic heart disease, involving a myocardial infarction (MI). Following myocardial infarction, the injured region and ventricle undergo structural changes which are thought to be caused by elevated stresses and reduction of strains in the infarcted wall. The fibrotic phase is defined as the period when the amount of new collagen and number of fibroblasts rapidly increase in the infarcted tissue. We studied through finite element analysis the mechanics of the infarcted and remodeling rat heart during diastolic filling. Biventricular geometries of healthy and infarcted rat hearts reconstructed from magnetic resonance images were imported in Abaqus©. The passive myocardium was modelled as a nearly incompressible, hyperelastic, transversely isotropic material represented by the strain energy function W = ½C(eQ − 1) with Q = bfE112 + bt(E222 + E332 + E322) + bfs(E122 + E212 + E132 + E312). Material parameters were obtained from literature [1]. As boundary conditions, the circumferential and longitudinal displacements at the base were set to zero. The radial displacements at the base were left free. A linearly increasing pressure from 0 to 3.80 kPa and 0.86 kPa, respectively, was applied to the endocardial surfaces of left and right ventricle. Average radial, circumferential and longitudinal strains during passive filling were −0.331, 0.135, 0.042 and −0.250, −0.078 and 0.046 for the healthy heart and the infarcted heart, respectively. The average radial, circumferential and longitudinal stresses were −1.196 kPa, 3.87 kPa in the healthy heart and 0.424 kPa and −1.90 kPa, 8.74 kPa and 1.69 kPa in the infarcted heart. The strains were considerable lower in the infarcted heart compared to the health heart whereas stresses were higher in the presence of an infarct compared to the healthy case. The results of this study indicate the feasibility of the models developed for a more comprehensive assessment of mechanics of the infarcted ventricle including extension to account for cardiac contraction.
Re-engineering technological strategies in teaching and learning in an open distance learning (ODL) environment is paramount as the demand for access to quality higher education escalates drastically on a year to year basis. The organisational framework requires change in order to accommodate the increasing number of students. In view of the changing higher education landscape and the increase in the number of students qualifying for higher education acceptance, open distance education has been opened to residential institutions. Despite the fact that demands is greater than supply in the higher education sector, the University of South Africa (Unisa), in reaction to the "competitive threat," has embarked on the re-evaluation of ODL as a component of its teaching and learning methodology. Unisa focussed on its pedagogical approaches as a primary means of maintaining its competitive edge. The challenges in the higher education sector are also attributed to the basic education sector that does not prepare students sufficiently for higher education. ODL, if applied appropriately, could be a strategy to address the issues of access, equality, and equity in a democratic South Africa. Pedagogical strategies that are functional and appropriate need to be applied in the higher education sector. Hence the research question is to determine what ODL strategies can be implemented to ensure that students are on par with traditional universities. Therefore, this paper explores the pedagogical strategies that colleges may use with the intent to improve delivery of teaching and learning in an ODL environment.
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