Impaired subendocardial contractile myofiber function in asymptomatic aged humans, as detected using MRI

• Published in: American journal of physiology. Heart and circulatory physiology Vol. 291; no. 4; pp. H1573 - H1579
• Main Authors: Lumens, Joost, Delhaas, Tammo, Arts, Theo, Cowan, Brett R, Young, Alistair A
• Format: Journal Article
• Language: English
• Published: United States American Physiological Society 01.10.2006
• Subjects: Adult; Aged; Aging; Aging - pathology; Aging - physiology; Female; Heart attacks; Heart Ventricles - pathology; Humans; Hypertension; Magnetic Resonance Imaging; Male; Middle Aged; Myocardial Contraction - physiology; Myofibrils - pathology; Myofibrils - physiology; NMR; Nuclear magnetic resonance; Stroke Volume - physiology; Studies; Ventricular Dysfunction, Left - diagnosis; Ventricular Dysfunction, Left - pathology; Ventricular Dysfunction, Left - physiopathology; Ventricular Function
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.00074.2006

1 Bioengineering Institute and 2 Department of Medicine, University of Auckland, Auckland, New Zealand; and Departments of 3 Biophysics and 4 Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands Submitted 18 January 2006 ; accepted in final form 18 April 2006 With aging, structural and functional changes occur in the myocardium without obvious impairment of systolic left ventricular (LV) function. Transmural differences in myocardial vulnerability for these changes may result in increase of transmural inhomogeneity in contractile myofiber function. Subendocardial fibrosis and impairment of subendocardial perfusion due to hypertension might change the transmural distribution of contractile myofiber function. The ratio of LV torsion to endocardial circumferential shortening (torsion-to-shortening ratio; TSR) during systole reflects the transmural distribution of contractile myofiber function. We investigated whether the transmural distribution of systolic contractile myofiber function changes with age. Magnetic resonance tissue tagging was performed to derive LV torsion and endocardial circumferential shortening. TSR was quantified in asymptomatic young [age 23.2 (SD 2.6) yr, n = 15] and aged volunteers [age 68.8 (SD 4.4) yr, n = 16]. TSR and its standard deviation were significantly elevated in the aged group [0.47 (SD 0.12) aged vs. 0.34 (SD 0.05) young; P = 0.0004]. In the aged group, blood pressure and the ratio of LV wall mass to end-diastolic volume were mildly elevated but could not be correlated to the increase in TSR. There were no significant differences in other indexes of systolic LV function such as end-systolic volume and ejection fraction. The elevated systolic TSR in the asymptomatic aged subjects suggests that aging is associated with local loss of contractile myofiber function in the subendocardium relative to the subepicardium potentially caused by subclinical pathological incidents. ejection; shortening; torsion; transmural Address for reprint requests and other correspondence: J. Lumens, Dept. of Biophysics, Cardiovascular Research Institute Maastricht, Maastricht Univ., PO Box 616, 6200 MD Maastricht, The Netherlands (e-mail: j.lumens{at}fys.unimaas.nl )