Exergy Analysis of the Heart with a Stenosis in the Arterial Valve

Autor(es)

Roll, Julio Brandao ^[1] ; Borges, Matheus Leone ^[2] ; Keutenedjian Mady, Carlos Eduardo ^[2] ; de Oliveira Junior, Silvio ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Polytech Sch, Av Luciano Gualberto 380, BR-05508010 Sao Paulo - Brazil

^[2] Univ Estadual Campinas, Sch Mech Engn, Mendeleyev St 200, BR-13083970 Campinas, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Entropy; v. 21, n. 6 JUN 2019.
• Citações Web of Science: 1

Resumo

In the past decade, several articles have proposed the use of an exergy perspective to analyze physiological systems of the human body under different physical conditions. Such a perspective focuses on the exergy transformations and the efficiency of the biological processes. This may aid the medical field in assessments of a patient's physical health by means of an index (exergy efficiency) based on the quality of the energy conversion in a given process within the human heart. As a follow-up, a model was developed to describe the evolution of the transvalvular pressure gradient in the aortic valve as a function of stenosis severity. This model was created using physiological data from 40 patients available in the literature, as well as 32 operating points from different bileaflet aortic valve prosthesis. A linear regression results in values around 14.0 kPa for the pressure gradient in the most severe case, evolving from 1.0 kPa for a healthy scenario. The thermodynamic model assesses the irreversibilities associated with energy conversion processes related to metabolism: exergy destroyed at the valves, exergy increased in the flow, and the power of the heart. Results indicate that destroyed exergy reaches values of 10 W (almost 10% of total basal metabolic rate of the whole body). Exergy efficiency is 15% for a healthy heart, decreasing as a function of the severity of the stenosis to values lower than 5%. (AU)

• Processo FAPESP: 15/22883-7 - Análise termodinâmica aplicada a sistemas biológicos
• Beneficiário: Carlos Eduardo Keutenedjian Mady
• Modalidade de apoio: Auxílio à Pesquisa - Regular