AGE ASSOCIATED CHANGES IN VASCULAR STIFFNESS PROPERTIES

在工业化社会中动脉僵硬和左

In industrialized societies increases in arterial stiffness and left ventricular (LV) mass are considered part of normative aging. However, considerable heterogeneity exists in the age-associated changes in these variables both across cultures as well as within a given population. The ultimate goals of this project are to address the issue of how alterations in arterial stiffness affect the myocardium and whether in outcome studies they relate to vascular insufficiency syndromes, e.g., stroke. We have initiated a pilot study in which measurements of cardiac mass (via NMR), filling properties and isovolumic relaxation time (via Doppler echocardiography), carotid pressure pulse (via applanation tomography) and arterial pulse wave velocity (Doppler sonography) are made in men and women who differ with respect to age, race, arterial pressure, body composition, and physical conditioning status. As expected, results indicate that with increasing age arterial stiffening leads to an increase in pulse wave velocity. This is associated with an early return of reflected pulse waves from peripheral sites which produce an augmented and late occurring peak of carotid pressure pulse. It is important to note that these arterial changes are, by and large, not detected by routine clinical measures of brachial arterial pressure and are independent of gender, but vary inversely with exercise capacity. Of note, also is that in highly physically conditioned older individuals (greater than 60 yrs of age) the arterial stiffness and reflected wave indices are markedly reduced relative to their sedentary age peers and do not differ from those of younger individuals, although the age-associated increase in systolic pressure persists. We have undertaken an initiative to extend many of these studies to Black Americans and to other non-Western populations in which different patterns of arterial pressure change occurs with aging (in China via a research contract (cf. #N01-AG-02-2118)). Long term goals include determination of whether "normative"age-associated changes in cardiac structure (i.e. increasing left ventricular mass) and function (delayed left ventricular relaxation and reduced early diastolic filling rates) are directly related to changes in arterial stiffness. If such is the case, a long-term intervention trial might be justified to see whether amelioration of arterial stiffness by medication or lifestyle intervention can attenuate these age-associated changes in cardiac structure and function and reduce future cardiovascular morbidity.