Modelling the Human Cardiac Fluid Mechanics. 4th ed

With the Karlsruhe Heart Model (KaHMo) we aim to share our vision of integrated computational simulation across multiple disciplines of cardiovascular research, and emphasis yet again the importance of Modelling the Human Cardiac Fluid Mechanics within the framework of the international STICH study. The focus of this work is on integrated cardiovascular fluid mechanics, and the potential benefits to future cardiovascular research and the wider bio-medical community

Mathematical modelling of cardiovascular fluid mechanics: physiology, pathology and clinical practice

The cardiovascular apparatus is a complex dynamical system that carries oxygen and nutrients to cells, removes carbon dioxide and wastes and performs several other tasks essential for life. The physically-based modelling of the cardiovascular system has a long history, which begins with the simple lumped Windkessel model by O. Frank in 1899. Since then, the development has been impressive and a great variety of mathematical models have been proposed. The purpose of this Thesis is to analyse and develop two different mathematical models of the cardiovascular system able to (i) shed new light into cardiovascular ageing and atrial fibrillation and to (ii) be used in clinical practice. To this aim, in-house codes have been implemented to describe a lumped model of the complete circulation and a multi-scale (1D/0D) model of the left ventricle and the arterial system. We then validate each model. The former is validated against literature data, while the latter against both literature data and numerous in-vivo non-invasive pressure measurements on a population of six healthy young subjects. Afterwards, the confirmed effectiveness of the models has been exploited. The lumped model has been used to analyse the effect of atrial fibrillation. The multi-scale one has been used to analyse the effect of ageing and to test the feasibility of clinical use by means of central-pressure blind validation of a parameter setting unambiguously defined with only non-invasive measurements on a population of 52 healthy young men. All the applications have been successful, confirming the effectiveness of this approach. Pathophysiology studies could include mathematical model in their setting, and clinical use of multi-scale mathematical model is feasible

Fluid mechanics study of the mitral valve complex

Issued as Report, Project no. E-19-56

Windkessel modeling of the human arterial system

Cardiovascular diseases are a major concern of our society. Millions of patients all around the world are affected by disorders such as arrhythmias or atherosclerosis. Moreover, finding new diagnostic techniques and treatments is of increased difficulty due to the complexity of cardiovascular medicine. In this context, the upcoming generations of experts must be well prepared for overcoming such a challenge. This project aims to develop an educational tool that will allow students to improve their understanding on cardiovascular fluid mechanics and physiology and will allow them to gain practical experience before dealing with real patients. A system modelling the arterial system, available at the Universidad Carlos III de Madrid, is used for this purpose. The educational tool is composed by a theoretical simulation interface and an acquisition and control program, created using MATLAB, and a practical environment based on a physical pneumatic-hydraulic device. A laboratory practice for the students has been developed describing how to work with both platforms.Ingeniería Biomédic

Heart valve isogeometric sequentially-coupled FSI analysis with the space–time topology change method

Heart valve fluid–structure interaction (FSI) analysis is one of the computationally challenging cases in cardiovascular fluid mechanics. The challenges include unsteady flow through a complex geometry, solid surfaces with large motion, and contact between the valve leaflets. We introduce here an isogeometric sequentially-coupled FSI (SCFSI) method that can address the challenges with an outcome of high-fidelity flow solutions. The SCFSI analysis enables dealing with the fluid and structure parts individually at different steps of the solutions sequence, and also enables using different methods or different mesh resolution levels at different steps. In the isogeometric SCFSI analysis here, the first step is a previously computed (fully) coupled Immersogeometric Analysis FSI of the heart valve with a reasonable flow solution. With the valve leaflet and arterial surface motion coming from that, we perform a new, higher-fidelity fluid mechanics computation with the space–time topology change method and isogeometric discretization. Both the immersogeometric and space–time methods are variational multiscale methods. The computation presented for a bioprosthetic heart valve demonstrates the power of the method introduced

Patient Specific Diagnostics for cardiovascular diseases based on diagnostic imaging: an application to the aneurism of the ascending aorta

In the framework of a collaboration between clinicians and engineers (namely, the Department of Radiology of the Brotzu Hospital in Cagliari and the group of experimental hydraulics at DICAAR - University of Cagliari), methodologies for the application of the in vitro study of the cardiovascular fluid mechanics to the support of the physical interpretation of the diagnostic imaging data are being tested. To this aim, we set up a mock-loop able to reproduce the physiologic pulsatile flow and designed to host a replica of aortic root made of transparent silicon rubber. Then, we developed a procedure to obtain a transparent and compliant replica of a patient specific ascending aorta from diagnostic images. The patient specific aorta model can be inserted in the mock-loop to study the fluid dynamics by means of particle image velocimetry techniques. We compared the flow in three cases, corresponding to physiological conditions, mild and severe aortic root dilation, observing significant differences in the redirection of the transvalvular jet and vortex evolution in the aortic flow. The observed fluid dynamics differences may have relevant implications on the thromboembolism and vascular tissue damage potential

Coronary fluid dynamics

Issued as Progress report, and Final report, Project no. E-25-69

Oscillatory and pulsatile flows in environmental, biological and industrial applications

International audienceThe understanding of oscillatory and pulsatile flows is of high interest for different environmental/coastal, biological/health and industrial applications. Marine and coastal environment is dominated by waves. The related oscillatory turbulent boundary layers are involved in different coastal engineering applications. In the circulatory system, the study of the pulsatile flow of blood is indispensable for the better comprehension of many cardiovascular diseases. In bio-industries, pulsed flows are used in the cleaning of fouling deposits in different equipment. These different flows require deep understanding of advanced concepts in fluid mechanics and need an adequate quantification of the involved parameters such as wall shear stress (WSS). This study shows interdisciplinary knowledge from different communities: Environment/Coastal engineering, Health/Medicine and Bio-Industries/Chemical engineering. The knowledge acquired within a specialty could be of interest to others. It is important to share and use knowledge beyond disciplines especially in fluid mechanics which is at the crossroads of different applications. This study aims transdisciplinary research strategies toward a holistic approach