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Cerebral blood flow changes with diuretic therapy in elderly subjects with systolic hypertension
Insights
Lowering blood pressure in elderly patients with systolic hypertension using hydrochlorothiazide did not significantly impair cerebral blood flow. Gradual BP reduction appears safe, though individual responses vary.
Area of Science:
- Gerontology
- Cardiovascular Medicine
- Neurology
Background:
- Systolic hypertension (SH) in the elderly raises concerns about compromised cerebral perfusion with blood pressure (BP) reduction.
- Understanding the impact of antihypertensive therapy on cerebral hemodynamics is crucial for this population.
Purpose of the Study:
- To investigate whether lowering BP in elderly patients with SH affects cerebral blood flow (CBF) and cerebrovascular resistance (CVR).
Main Methods:
- Fifteen elderly patients with SH were studied untreated and during hydrochlorothiazide treatment.
- Measurements included BP, CBF (using 133-Xenon inhalation), plasma renin activity, and blood chemistries.
- Cerebrovascular response to CO2 was also assessed.
Main Results:
- Hydrochlorothiazide treatment lowered BP from 186/90 to 160/86 mmHg without significant changes in average gray matter flow (Fg) or CVR.
- A trend suggested decreased CVR in normotensive patients and decreased Fg in non-normotensive patients.
- Cerebrovascular response to CO2 was impaired in both treated and untreated states.
Conclusions:
- Cautious, gradual BP reduction with thiazide diuretics in elderly SH patients generally does not impair cerebral perfusion.
- Individual variations in response exist, necessitating further research to fully characterize them.
Abstract:
It has been feared that lowering the blood pressure (BP) of elderly patients with systolic hypertension (SH) may compromise cerebral perfusion. To test this hypothesis, BP, cerebral blood flow (CBF), plasma renin activity (PRA), blood counts, urinary and serum electrolytes and other blood chemistries were measured in fifteen elderly patients (ages 61-76 years) with SH (systolic BP greater than 170 and diastolic BP less than 100 mmHg). Gray matter flow (Fg) was calculated from clearance curves of inhaled 133-Xenon. All subjects were studied while untreated, as well as during long-term treatment (average 15 weeks) with hydrochlorothiazide. BP fell during treatment from 186/90 to 160/86 while average Fg and cerebrovascular resistance (CVR) were not significantly changed. There was some suggestion, however, that in patients who became normotensive the CVR decreased (p less than 0.05) while in those who did not Fg fell (p less than 0.05). Cerebrovascular response to 5% CO2 inhalation was impaired during both the treated and untreated states. Individual changes in Fg and CVR did not correlate with changes in BP or with changes in PRA, electrolytes or other chemistries. In general, cautious, gradual reduction of BP with a thiazide diuretic in SH of the elderly seems not to impair cerebral perfusion, but individual differences exist and further studies are needed to characterize them.