Interplay of Aging and Hypertension in Cardiac Remodeling: A Mathematical Geometric Model - Fig 2

<p>Geometric changes in HTN^Pos patients along with aging: (A) Correlation between age and interventricular septum dimension (IVSd); (B) Correlation between age and interior radius; (C) Correlation between age and exterior radius; (D) Elastic changes (<i>E</i>) in HTN^Pos patients along with aging; (E) Elastic changes (<i>υ</i>) in HTN^Pos patients along with aging. HTN^Neg = does not have hypertension; HTN^Pos = has hypertension.</p

The relationship between E and echocardiographic intraventricular pressure in the younger and older cohorts.

<p>A: The relationship between and E value in various age group. B: The exponential correlation between age and E in the regression analysis.</p

The correlations between and E both in the clinical statistics and the mathematical models.

<p>A and B: The relationship between and E in clinical statistics, and C: in the mathematical model.  = estimated intraventricular pressure by the ratio of early diastolic mitral inflow velocity and the averaged early diastolic velocity of mitral annulus in tissue Doppler imaging; .</p

Clinical and echocardiographic characteristics of the younger (50.3 ± 11.2 years) and the older (70.7 ± 7.2 years) participants.

<p>Clinical and echocardiographic characteristics of the younger (50.3 ± 11.2 years) and the older (70.7 ± 7.2 years) participants.</p

Characterization of Aging-Associated Cardiac Diastolic Dysfunction

<div><p>Aims</p><p>Diastolic dysfunction is common in geriatric heart failure. A reliable parameter to predict myocardium stiffness and relaxation under similar end-diastolic pressure is being developed. We propose a material and mathematical model for calculating myocardium stiffness based on the concept of linear correlation between and wedge pressure.</p><p>Methods and Results</p><p>We enrolled 919 patients (male: ). Compared with the younger population of controls (mean age: years; ; male: ), the elderly (mean age: ; ; male: ) had a greater prevalence of hypertension, diabetes mellitus, and coronary artery disease (all ). We collected their M-mode and 2-D echocardiographic volumetric parameters, intraventricular filling pressure, and speckle tracking images to establish a mathematical model. The feasibility of this model was validated. The average early diastolic velocity of the mitral annulus assessed using tissue Doppler imaging was significantly attenuated in the elderly (: vs. ; ) and corresponded to the higher estimated wedge () pressure ( vs. ; ) in that cohort. E (Young's modulus) was calculated to describe the tensile elasticity of the myocardium. With the same intraventricular filling pressure, E was significantly higher in the elderly, especially those with values . Compared with diastolic dysfunction parameters, E also presented sentinel characteristics more sensitive for detecting early myocardial relaxation impairment, which indicates stiffer myocardium in aging hearts.</p><p>Conclusion</p><p>Our material and geometric mathematical model successfully described the stiffer myocardium in aging hearts with higher intraventricular pressure. Additional studies that compare individual differences, especially in health status, are needed to validate its application for detecting diastolic heart failure.</p></div

Comparison between the present study’s model and the previous Chang et al. [18] model.

<p>Comparison between the present study’s model and the previous Chang et al. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0168071#pone.0168071.ref018" target="_blank">18</a>] model.</p

An elliptical model of the thick-walled ventricle and components of cardiac wall stress.

<p>An elliptical model of the thick-walled ventricle and components of cardiac wall stress.</p

(A) Comparison between using cylindrical and elliptical models for HTN^Neg and HTN^Pos participants (<i>E</i> value); (B) Comparison between using cylindrical and elliptical models for HTN^Neg and HTN^Pos participants (<i>υ</i>).

<p>HTN^Neg = does not have hypertension; HTN^Pos = has hypertension.</p

Multivariate regression analyses for the independence of E value in older patients with diastolic dysfunction.

<p>Abbreviations: see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0097455#pone-0097455-t001" target="_blank">Table 1</a>.</p

Summary of geometric changes in HTN^Pos patients along with aging.

<p>HTN^Neg = does not have hypertension; HTN^Pos = has hypertension.</p