Cardiovascular regulatory functions in elderly patients with hypertension

Author(s): Shimada, K., Matsubayashi, K., Chikamori, T., Kuzume, O. , H, Ozawa, T.

Journal/Book: Hypertension. 1989; 5:

Abstract: To dissociate the effects of an elevated blood pressure an the cardiovascular regulatory functions from those of aging in the hypertensive elderly individual, resting hemodynamic measurements and circulatory autonomic functions in 30 elderly (mean age, 66 years) hypertensive (World Health Organization stages I and II) patients were compared with those in 30 healthy elderly (mean age, 65 years) normotensive volunteers. The elderly hypertensive group showed a significantly lower cardiac index and higher total peripheral resistance. (3-Receptor sensitivity, as determined by chronotropic dose of infused isoproterenol, and baroreceptor reflex sensitivity index, derived from phase II, but not phase IV, of Valsalva's maneuver, were only slightly but significantly reduced in the hypertensive group. The variability of heart rate at rest as an index of parasympathetic control of heart was similar between these two groups. Plasma norepinephrine level was significantly inversely related to resting mean blood pressure (r=-0.31, p<0.05) when analyzed as a whole group. Plasma renin activity, but not plasma aldosterone, was significantly decreased in the hypertensive group. To define the effects of age itself, these parameters in normotensive elderly subjects were also compared with those in 12 young normotensive subjects (mean age, 23 years). Although resting hemodynamic measurements did not differ, various circulatory autonomic funetions were significantly different between these two age groups. The variability of heart rate in 24-hour ambulatory monitoring, ß-receptor responsiveness, resting vagal cardiac activity, and baroreceptor reflex sensitivity derived from phase IV of Valsalva's maneuver were significantly depressed in the elderly. Resting plasma norepmephrine level was elevated and renin-aldosterone system decreased in the elderly. Thus, the hemodynamic pattern of elderly hypertensive patients with mild essential hypertension is of the low-output, high peripheral resistance type. Neither the sympathetic nervous nor the renin-angiotensin system is likely to be responsible for this increase in peripheral resistance. Furthermore, in contrast to the currently prevailing belief, high blood pressure, although an important modulating factor in the younger patients, has very limited, if any, influence an the cardiovascular regulatory functions in older subjects whose autonomic functions have already been substantially altered by advancing age.

Keyword(s): elderly

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