Antihypertensive Therapy Increases Cerebral Blood Flow and Carotid Distensibility in Hypertensive Elderly Subjects

Abstract

Abstract-Many physicians are reluctant to lower blood pressure to recommended levels in elderly hypertensive patients because of concern about producing cerebral hypoperfusion. Because hypertension is associated with potentially reversible structural and functional alterations in the cerebral circulation that may improve with treatment, we investigated whether long-term pharmacological reduction of systolic blood pressure will improve, rather than worsen, cerebral blood flow and its regulation. Three groups of elderly subjects 65 years of age or older were studied prospectively: normotensive subjects (Nϭ19), treated hypertensive subjects with systolic pressure Ͻ140 mm Hg (Nϭ18), and uncontrolled hypertensive subjects with systolic pressure Ͼ160 mm Hg at entry into the study (Nϭ14).We measured beat-to-beat blood flow velocity in the middle cerebral artery (transcranial Doppler ultrasonography), finger arterial pressure (photoplethysmography), and pulsatile distensibility of the carotid artery (duplex Doppler ultrasonography) at baseline and after 6 months of observation or antihypertensive therapy. After baseline hemodynamic measurements, uncontrolled hypertensive subjects underwent aggressive treatment with lisinopril with or without hydroclorothiazide or, if not tolerated, nifedipine or an angiotensin receptor blocker to bring their systolic pressure Ͻ140 mm Hg for 6 months. The other 2 groups were observed for 6 months. After 6 months of successful treatment, uncontrolled hypertensive subjects had significant increases in cerebral blood flow velocity and carotid distensibility that was not seen in the other groups. Treatment reduced cerebrovascular resistance and did not impair cerebral autoregulation. Therefore, judicious long-term treatment of systolic hypertension in otherwise healthy elderly subjects does not cause cerebral hypoperfusion. Key Words: aging Ⅲ angiotensin-converting enzyme inhibitor Ⅲ brain Ⅲ hemodynamics Ⅲ ultrasonography A lthough the treatment of systolic hypertension has been shown in prospective randomized controlled trials to reduce cardiovascular morbidity and mortality in subjects up to age 80, many physicians are reluctant to lower systolic blood pressure (BP) to the recommended level of 140 mm Hg or lower in elderly patients, because of concern that aggressive treatment may cause cerebral hypoperfusion and associated syncope, falls, or cognitive dysfunction. 1,2 Because hypertension is associated with potentially reversible structural and functional changes in the cerebral circulation, we hypothesized that long-term BP reduction would improve, rather than worsen, cerebral blood flow and its regulation. Therefore, we conducted the current study to determine the effects of systolic BP reduction over 6 months on cerebral perfusion in elderly hypertensive patients. We also examined structural and functional changes in the cerebral vasculature potentially affected by BP-lowering, including carotid distensibility and cerebral autoregulation. Methods DesignThe study was a prospective 3-gro...

Association between arterial stiffness and cerebrovascular resistance in the elderly

“…This could be due to the confounding effect of medications not only on mean arterial pressure, but also on arterial stiffness. 11 Differential effects of the medications listed in Table 1 could not be determined because of the small sample size.…”

“…The first is that prevention of, or slowing the rate of, arterial stiffness progression with aging, for example by increased physical activity, 33,34 might be a critical factor in maintaining CBF. The second is that individuals with elevated arterial stiffness might benefit from treatments 11 designed to reduce arterial stiffness that might in turn reduce CVRi allowing an increase in CBF.…”

“…10 The current literature provides indirect evidence of an association between arterial stiffness and CBF. 11,12 Six months of anti-hypertensive treatment resulted in not only a reduced perfusion pressure and increased common carotid distensibility, but also an elevated CBF velocity. 11 Furthermore, in young adults, an acute increase in arterial stiffness and attenuation of CBF was observed following the administration of the endogenous nitric oxide (NO) synthase inhibitor asymmetric dimethylarginine.…”

“…11,12 Six months of anti-hypertensive treatment resulted in not only a reduced perfusion pressure and increased common carotid distensibility, but also an elevated CBF velocity. 11 Furthermore, in young adults, an acute increase in arterial stiffness and attenuation of CBF was observed following the administration of the endogenous nitric oxide (NO) synthase inhibitor asymmetric dimethylarginine. 12 This study was designed to test the hypothesis that elevated arterial stiffness in an elderly population is associated with elevated cerebrovascular resistance and reduced CBF.…”

Cardiac surgery and hypertension: a dangerous association that must be well known

“…Uncontrolled hypertension is associated with potentially reversible structural and functional changes in the cerebral circulation [1], and at an increasing risk for cerebral, cardiac, and renal events [2]. However, this condition has not been a topic of much evaluation as to being defined within the field of cardiac surgery.…”