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Cardiovascular System:
Published in Michel R. Labrosse, Cardiovascular Mechanics, 2018
Heart murmurs are usually a result of a valve abnormality. A valve stenosis refers to a faulty opening of the valve and can be a result of stiff valve flaps or a narrowing of the valve annulus. This may be a congenital defect, caused by an illness such as rheumatic fever. With aging, calcification of the valve flaps also results in stenosis. A valve insufficiency (or regurgitation) refers to a faulty closure of the valve that allows for the backflow of blood. This “leak” can also be a result of a congenital condition, disease, or aging. Both conditions result in less forward blood flow and a drop in stroke volume and cardiac output, which can lead to heart failure. Defective valves may either be replaced with a valve prosthesis—a mechanical valve or a pig or cow valve—or be repaired. These aspects, along with the structure and function of the aortic and mitral valves, will be discussed in more detail in Chapters 9 and 10. Tissue engineering may soon allow for the development of valves from a patient’s own cells.
Noninvasive Diagnosis Using Sounds Originating from within the Body
Published in Robert B. Northrop, Non-Invasive Instrumentation and Measurement in Medical Diagnosis, 2017
Aortic regurgitation, on the other hand, occurs because the damaged aortic valve does not close completely. Again, there is a high-velocity jet of blood forced back into the left ventricle by aortic back pressure during diastole (when the left ventricle is relaxed). This back pressure makes it difficult for the left atrium to fill the left ventricle, and of course, the heart must work harder to pump a given volume of blood into the aorta. The aortic regurgitation murmur is also of relatively high pitch, and has a swishing quality (Guyton 1991).
Coanda Effect in a Human Body
Published in Noor A. Ahmed, Coanda Effect, 2019
Mitral regurgitation affects nearly 150 million people worldwide and occurs in men and women equally [48]. Mitral regurgitation is the leaking of blood flow in the heart, otherwise not present in a healthy body. The condition may occur due to pathology affecting one or more components of the mitral valve or due to annular dilatation and geometrical distortion of the sub-valvular apparatus secondary to the left ventricular, associated with cardiomyopathy or coronary artery disease.
Fluid-structure interaction assessment of blood flow hemodynamics and leaflet stress during mitral regurgitation
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
Saeed Adham Esfahani, Kamran Hassani, Daniel M. Espino
Mitral valve regurgitation is a condition in which the valve does not close tightly and there is an abnormal reversal of blood flow from the left ventricle to the left atrium. This increases the pressure in the left atrium and may lead to complications such as dyspnea, fatigue, orthopnea, and pulmonary edema. Mitral valve regurgitation is an important health issue. More than three millions people in the USA suffer from moderate or severe regurgitation (Athappan et al. 2017). In spite of the fact that measuring hemodynamic parameters in left ventricle and mitral valve stress patterns are significantly challenging, numerical analyses can be used to develop new models to further understand this issue (Gao et al. 2014). Coincident with developments in non-invasive blood flow imaging (echo-doppler and Magnetic Resonance Imaging, MRI), in recent years significant studies have combined such imaging with numerical simulation (Wong et al. 2017); with applications to human mitral valves, including prediction of disease progression and treatment.
A Cartesian grid generation technique for 2-D non-Newtonian blood flow through a bileaflet mechanical heart valve
Published in International Journal for Computational Methods in Engineering Science and Mechanics, 2021
Khellaf Belkhiri, Boussad Boumeddane
Malfunction of the heart valves affects their hemodynamic performance. The hemodynamics are affected by a defective valve in two primary ways: (i) by stenosis, which is a narrowing of the valve to give a larger resistance to blood flow and therefore a larger pressure drop across the valve, (ii) by incompetence, which is the failure of the valve to close completely. Blood then flows in the reverse direction (regurgitation) when the valve should be shut [5]. Both of these conditions reduce the efficiency of the heart and place additional stress and strain upon it. The decision to perform corrective surgery on the natural valve or replace it with a prosthetic valve is often made on the basis of an evaluation of the functional impairment of the natural valve.
Transcatheter valve-in-valve implantation for degenerated bioprosthetic aortic and mitral valves – an update on indications, techniques, and clinical results
Published in Expert Review of Medical Devices, 2021
Michele Gallo, Michel Pompeu B. O. Sá, Ilias P. Doulamis, Nabil Hussein, Pietro L. Laforgia, Polydoros N. Kampaktsis, Ana Paula Tagliari, Enrico Ferrari
The role of echocardiography is crucial to identify the mechanism of bioprosthetic valve failure and exclude contraindications for V–in-V replacement. For example, if a severe patient-prosthesis mismatch is present in an aortic bioprosthesis with high gradients V–in-V replacement should not be pursued. Similarly, if the mechanism of regurgitation is due to either severe paravalvular leak or active endocarditis, the patient should be evaluated for surgical valve replacement as a definite treatment [37].