[Reduced arterial compliance with advancing age].
The term "compliance" is generally used as softness of the arterial wall. Fundamentally, compliance characterizes property of a chamber, being defined as deltaV/deltaP. It implies that how easily volume (V) of the chamber changes in response to unit pressure (P) change. However, in reality, the arterial system is not such a simple chamber but a complicated branched tubing system, in which compliance components are distributed along the tubing. It can be simplified as a single tube model, in which we can regard compliance as the sum of proximal portion as a determinant of characteristic impedance of the aorta and distal portion consisting of terminal impedance of the peripheral arterial bed. Such distributed model enables us to simulate pulse wave propagation and reflection, actually occurred in real arteries. This paper deals with parameters relating to arterial compliance corresponding to such distributed model. Arterial compliance is reduced with advancing age. This phenomenon has been widely recognized by epidemiological studies on blood pressure, in which systolic and pulse pressures are increased with aortic reflection without significant change in diastolic pressure. Also, many investigators reported age-dependent compliance declines by assessing compliance-relating parameters including cross-sectional compliance, pulse wave velocity and augmentation index. This reduced compliance may affect the heart as a pulsatile afterload and adversely alter myocardial energy balance.
Miyashita
Hiroshi
H
Section of Cardiovascular Medicine, Ishibashi General Hospital.
Shimada
Kazuyuki
K
D000368:Aged; D000375:Aging / Q000473:pathology / Q000502:physiology*; D000818:Animals; D001158:Arteries / Q000473:pathology / Q000503:physiopathology*; D001161:Arteriosclerosis / Q000209:etiology / Q000503:physiopathology; D001794:Blood Pressure; D003187:Compliance; D004730:Endothelium, Vascular / Q000503:physiopathology; D006352:Heart Ventricles / Q000503:physiopathology; D006801:Humans; D010101:Oxygen Consumption