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Open AccessArticle

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

1
Polytechnic School of the University of São Paulo, Av. Luciano Gualberto 380, São Paulo 05508-010, Brazil
2
School of Mechanical Engineering, University of Campinas, Mendeleyev St. 200, Campinas 13083-970, Brazil
*
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Entropy 2019, 21(6), 563; https://doi.org/10.3390/e21060563
Received: 6 April 2019 / Revised: 20 May 2019 / Accepted: 1 June 2019 / Published: 4 June 2019
(This article belongs to the Section Entropy and Biology)
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%. View Full-Text
Keywords: exergy analysis; cardiovascular system; heart; human body; aortic stenosis exergy analysis; cardiovascular system; heart; human body; aortic stenosis
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Brandão Roll, J.; Leone Borges, M.; Keutenedjian Mady, C.E.; de Oliveira Junior, S. Exergy Analysis of the Heart with a Stenosis in the Arterial Valve. Entropy 2019, 21, 563.

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