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Roger D. Kamm. Bottom, Karen Evelyn, 1975- Massachusetts Institute of Technology. Department of Mechanical Engineering 2005-08-22T18:07:08Z 2005-08-22T18:07:08Z 1999 1999 http://hdl.handle.net/1721.1/9405 43185327 Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1999. Includes bibliographical references (p. 125-127). External cardiac assist (ECA) is a noninvasive, counterpulsative method that aims to provide temporary aid to the failing heart through increased diastolic augmentation and decreased systolic after load. These counterpulsative benefits are achieved by sequentially inflating cuffs on the calves, thighs. and buttocks 180 degrees out-of-phase with the left ventricle. Previous clinical and computational studies have demonstrated the efficacy of ECA is highly dependent on the selection of the control scheme parameters for the device. These control parameters include: the maximum external pressure applied by each cuff, the starting time of cuff inflation and deflation, the time between adjacent cuff inflations, and the total time to inflate and deflate the cuffs from atmospheric to maximum pressurization and vice versa. Optimization of these control parameters, however, necessitates a complete understanding of the hemodynamics created by ECA. Clinical ECA devices used currently have been designed without the benefit of this understanding. Thus, a numerical model has been developed that simulates cardiovascular hemodynamics during the operation of an ECA device. The model includes a 28-element distributed arterial system with boundary conditions simulating the left ventricle, bifurcations, and peripheral arterial vessels. Some of the hemodynamic phenomena studied in the model include: the collapse and subsequent emptying of arteries as external pressure is applied, the refilling of arteries as external pressure in the cuffs is released, and the changes in aortic pressure, cardiac output, and blood flow distribution resulting from operation of the ECA device. By quantitatively studying these hemodynamic phenomena, the parameters governing the application and control of the ECA device were systematically varied and an optimum set of control parameters was determined. by Karen Evelyn Bottom. S.M. 127 p. 8291556 bytes 8291314 bytes application/pdf application/pdf eng Massachusetts Institute of Technology M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 Mechanical Engineering A numerical model of cardiovascular fluid mechanics during external cardiac assist Thesis application/pdf false Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="87418909-a72c-49cd-b7a0-9e2930f1e16b"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>eng</Language> <Title>A numerical model of cardiovascular fluid mechanics during external cardiac assist</Title> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>1999</PublicationDate> <Authors> <Author> <DisplayName>Bottom, Karen Evelyn, 1975-</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://dspace.mit.edu/handle/1721.1/7582</License> <Keyword>Mechanical Engineering</Keyword> <Abstract>External cardiac assist (ECA) is a noninvasive, counterpulsative method that aims to provide temporary aid to the failing heart through increased diastolic augmentation and decreased systolic after load. These counterpulsative benefits are achieved by sequentially inflating cuffs on the calves, thighs. and buttocks 180 degrees out-of-phase with the left ventricle. Previous clinical and computational studies have demonstrated the efficacy of ECA is highly dependent on the selection of the control scheme parameters for the device. These control parameters include: the maximum external pressure applied by each cuff, the starting time of cuff inflation and deflation, the time between adjacent cuff inflations, and the total time to inflate and deflate the cuffs from atmospheric to maximum pressurization and vice versa. Optimization of these control parameters, however, necessitates a complete understanding of the hemodynamics created by ECA. Clinical ECA devices used currently have been designed without the benefit of this understanding. Thus, a numerical model has been developed that simulates cardiovascular hemodynamics during the operation of an ECA device. The model includes a 28-element distributed arterial system with boundary conditions simulating the left ventricle, bifurcations, and peripheral arterial vessels. Some of the hemodynamic phenomena studied in the model include: the collapse and subsequent emptying of arteries as external pressure is applied, the refilling of arteries as external pressure in the cuffs is released, and the changes in aortic pressure, cardiac output, and blood flow distribution resulting from operation of the ECA device. By quantitatively studying these hemodynamic phenomena, the parameters governing the application and control of the ECA device were systematically varied and an optimum set of control parameters was determined.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>