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

PLoS One. 2016 Dec 15;11(12):e0168071. doi: 10.1371/journal.pone.0168071. eCollection 2016.

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.

MeSH terms

  • Age Factors
  • Aged
  • Aged, 80 and over
  • Aging / physiology*
  • Blood Pressure / physiology
  • Elasticity / physiology
  • Female
  • Heart / physiology
  • Humans
  • Hypertension / pathology
  • Hypertension / physiopathology*
  • Male
  • Models, Biological
  • Models, Theoretical*
  • Myocardium / pathology

Grants and funding

This research was supported in part by the Headquarters of University Advancement at the National Cheng Kung University; Health Promotion Program: Blood Pressure Control from Health Promotion Administration, Ministry of Health and Welfare, Taiwan, ROC; grants from Ministry of Science and Technology, Taiwan (MOST 103-2628-B-006-002-MY4, 105-2314-B-006-057-MY3, 103-2221-E-006 -032) and a grant from National Cheng Kung University Hospital (2012-2015, P.Y.L.). The investigator (P.Y.L.) was granted by “A Landmark Project to Promote Innovation & Competitiveness of Clinical Trials by the Excellent Clinical Trial and Research Center in National Cheng Kung University Hospital, Ministry of Health and Welfare, Taiwan.”