title: Interplay of Aging and Hypertension in Cardiac Remodeling: A Mathematical Geometric Model.
abstract: Hypertensive disorder can cause cardiac deformities. Elastic characteristic parameters, like Young's modulus of elasticity (E) derived from a traditional cylindrical model, increase significantly with aging. However, the geometric and component changes of aging hearts because of chronic hypertension remain unknown. To better describe the effects, we propose an elliptical elastic and mathematical model to evaluate myocardial stiffness. Ninety-six hypertensive patients (HTNPos) (men: 59.3%; age ≥ 65 years: 20.8%) were enrolled and compared with normotensive controls (HTNNeg) (n = 47, 48.9%). HTNPos patients had a thicker interventricular septum in diastole (IVSd) (HTNPos: 0.96 ± 0.21 cm vs. HTNNeg: 0.77 ± 0.15; p = 0.005) and higher intracardiac pressure (e/e': 9.06 ± 4.85 cm vs. 7.76 ± 3.41; p = 0.01), especially the elderly (> 65 years) (IVSd: 1.03 ± 0.19 cm, e/e': 11.39 ± 1.99; p = 0.006 and 0.01, respectively). Nevertheless, the internal dimension decreased more significantly in the HTNPos rather than in the HTNNeg elderly (5.23 ± 0.46 vs. 4.74 ± 0.69 cm; p = 0.02). We found different directions of cardiac remodeling with normotensive and hypertensive loads. Different from the longitudinal and circumferential strain, E and Poisson's ratio (υ) are values that directly present the rigidity of myocardium. E was significantly higher in the elderly (8011.92 ± 2431.85 vs. 6052.43 ± 3121.50; p = 0.02), whereas υ was significantly higher in all HTNPos patients (0.73 ± 0.12 vs. 0.61 ± 0.07; p < 0.001). Because E and υ reflected the material changes of myocardium in the HTNPos elderly, the proposed elliptical mathematical heart model better describes the geometric deformity induced by aging and hypertension.
authors.affiliation: Division of Cardiology, Internal Medicine, Chi-Mei Medical Center, Tainan, Taiwan.|Department of Engineering Science, National Cheng Kung University, Tainan, Taiwan.|Department of Biotechnology, Southern Taiwan University of Science and Technology, Tainan, Taiwan.
authors.forename: Wei-Ting
authors.initials: WT
authors.lastname: Chang
authors.affiliation: Department of Engineering Science, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Jung-San
authors.initials: JS
authors.lastname: Chen
authors.affiliation: Department of Engineering Science, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Meng-Hang
authors.initials: MH
authors.lastname: Tsai
authors.affiliation: Division of Cardiology, Internal Medicine, National Cheng Kung University Hospital, Tainan, Taiwan.
authors.forename: Wei-Chuan
authors.initials: WC
authors.lastname: Tsai
authors.affiliation: Department of Engineering Science, National Cheng Kung University, Tainan, Taiwan.
authors.forename: Jer-Nan
authors.identifier: http://orcid.org/0000-0002-3052-2833
authors.initials: JN
authors.lastname: Juang
authors.affiliation: Division of Cardiology, Internal Medicine, National Cheng Kung University Hospital, Tainan, Taiwan.|Institute of Clinical Medicine, National Cheng Kung University, Tainan, Taiwan.|Graduate Institute of Clinical Medical Sciences, College of Medicine, China Medical University, Taichung, Taiwan.
authors.forename: Ping-Yen
authors.identifier: http://orcid.org/0000-0002-3643-5204
authors.initials: PY
authors.lastname: Liu
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D004548:Elasticity / Q000502:physiology; D005260:Female; D006321:Heart / Q000502:physiology; D006801:Humans; D006973:Hypertension / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D008954:Models, Biological; D008962:Models, Theoretical; D009206:Myocardium / Q000473:pathology