Simulation of the Effect of Atrioventricular Block on Left Ventricular Performance
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Date
2021-10
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Addis Ababa University
Abstract
With the growing interests in multiscale computation studies in different fields in recent decades, its application in the biomedical field has been of great importance specially to analyse, process, design and diagnose different biological activities at both microscopic and macroscopic levels. This has resulted into improvement in medical technologies and disease management. Despite the continued efforts to improve computational interventions in biomedical studies, little has been done to understand the cardiovascular system (heart) in terms of its electrical behaviour in relation to its mechanical responses. This gap in computational knowledge especially in normal cardiac physiology and pathological conditions presents a problem to be tackled in order to improve diagnosis, and treatment of different cardio pathological conditions. This thesis investigates the effects of AVN block on left ventricular performance via an electromechanical coupled setup.
The cardiac electromechanical properties work on the principles that the electrical impulses from Sinoatrial node (SAN) in the atria via the AVN convey to the ventricles causing mechanical contraction and hence pumping of the blood. A 3D left ventricular model was developed on SOLIDWORKS and imported into COMSOL Multiphysics. Furthermore, through simulation using finite element (FE) analysis software COMSOL Multiphysics, a parametric study was performed on the effect of atrioventricular block on left ventricular function.
Based on the data adopted, the effects of varying the current stimulus as parameter were noted and discussed. From our model, observable and quantitative results were derived. The results obtained in this thesis allow the drawing of essential conclusions with regards to the left ventricular mechanical response to degrees of atrioventricular blockage which are essential to further computational studies. Also, in the simplified ventricular model the orthotropic nature of the myocardium, fiber orientations, and fluid mechanics were considered. The transmembrane chemical effects such as calcium handling, potassium, sodium concentration in the cytoplasm and mechano-electrical feed-back were neglected. The perturbations of the electrical impulses for the three AVN block cases resulted into variations in action potential durations (APDs). The variations were also noted on the myocardial voltage dependent stress during the simulations. Conclusively, the LV mechanical function was greatly affected by the variations of impulse stimulus due to AVN blockage.
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Keywords
Heart tissue, Electromechanical model, Heart modeling, Heart diseases, COMSOL Multiphysics