Cerebral hemodynamics after short and long‐term reduction in blood pressure in mild and moderate hypertension

Abstract

This study tested the hypothesis that in contrast to the salutary effects of long-term antihypertensive therapy, reducing blood pressure (BP) at the initial stage of antihypertensive therapy compromises brain perfusion and dynamic cerebral autoregulation in patients with mild and moderate hypertension. Cerebral blood flow (CBF) velocity, BP, and cardiac output (CO) were measured in the supine position and during head-up tilt (HUT) in newly diagnosed patients with mild and moderate hypertension and in healthy volunteers. Beat-to-beat changes in BP and CBF velocity were quantified using transfer function analysis to evaluate dynamic autoregulation. After 1–2 week of administration of losartan/hydrochlorothiazide (50/12.5 – 100/25 mg, once daily) (short-term), BP was reduced in mild (from 143 ± 7/88 ± 4 to 126 ± 12/77 ± 6 mmHg) and moderate hypertension (from 163 ± 11/101 ± 9 to 134 ± 17/84 ± 9 mmHg, all P < 0.05). These reductions in BP were well maintained over the 3–4 month period of treatment (long-term). CBF velocity did not change after reductions in BP, while cerebrovascular resistance index was reduced by 17% (P < 0.05). During HUT, CBF velocity and CO were reduced similarly in control subjects and in patients with hypertension and these changes were not altered after reductions in BP. Before treatment, transfer function gain was reduced in moderate hypertension (P < 0.05). However, this reduced transfer function gain was restored to the level of control subjects after reductions in BP. These findings, contrary to our hypothesis, indicate that brain perfusion and dynamic autoregulation are not compromised in patients with mild and moderate hypertension after either short or long-term reduction in BP.