ME 04-3 EPIDEMIOLOGY AND CONSEQUENCES OF EARLY VASCULAR AGING

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Abstract

Arterial structure and function change progressively with advancing age. Owing to long-lasting repetitive stretch with intermittent cardiac contraction, elastic fibers in the tunica media of large arteries gradually degenerate and are replaced by collagenous fibers. Such medial degeneration causes elastic arteries to stiffen and dilate. However, the speed of the vascular aging varies considerably among individuals; a discrepancy often exists between the chronological age of an individual and the biological age of his or her arteries. In susceptible individuals the vascular aging process can be accelerated under the presence of various risk factors including hypertension, smoking, metabolic disorders, high sodium intake and hereditary traits. Early vascular aging is generally detected by vascular function tests such as pulse wave velocity (PWV) and pulse wave analysis. Stiffening of large elastic arteries increases the PWV, increases the amplitude of the incident pressure wave, and hastens the return of the reflected pressure wave. Consequent widening of the aortic pulse pressure elevates left ventricular afterload during systole and reduces coronary flow during diastole, thus predisposing to heart failure and myocardial ischemia. The excessive pulsatile pressure is also transmitted into the vulnerable microvasculature in the kidney and brain to cause albuminuria and lacunar infarction. Furthermore, aortic stiffening increases blood flow reversal in early diastole in the proximal descending aorta. The increased aortic flow reversal reduces renal blood flow and glomerular filtration rate, and in addition, it raises the risk of retrograde cerebral embolism of aortic mobile plaques. Such deleterious impacts of the central hemodynamic abnormalities on the vital end-organs predispose the patients with early vascular aging to premature cardiovascular diseases. Indeed, epidemiological prospective studies have demonstrated that aortic PWV and central hemodynamic indices predict the occurrence of cardiovascular diseases including myocardial infarction, stroke and end-stage renal disease. Although vascular aging is considered an inevitable and irreversible process, it can be delayed through lifestyle modification and/or de-stiffening therapy with effective antihypertensive medication. Therefore, early prevention of vascular aging is a key strategy to reduce cardiovascular risk and improve prognosis in patients with hypertension.

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