Evaluation of cerebral autoregulation performance in patients with arterial hypertension on drug treatment.

Abstract

Cerebral autoregulation (AR) keeps cerebral blood flow constant despite fluctuations in systemic arterial pressure. The final common AR pathway is made up of vasomotor adjustments of cerebrovascular resistance mediated by arterioles. Structural and functional changes in the arteriolar wall arise with age and systemic arterial hypertension. This study evaluated whether AR is impaired in hypertensive patients and whether this impairment differs with disease control. Three groups of patients were prospectively compared: hypertensive patients under treatment with systolic blood pressure (SBP) <140 and diastolic blood pressure (DBP) <90mmHg (n=54), hypertensive patients under treatment with SBP>140 or DBP>90mmHg (n=31), and normotensive volunteers (n=30). Simultaneous measurements of cerebral blood flow velocity (CBFV) and BP were obtained by digital plethysmography and transcranial Doppler, and the AR index (ARI) was defined according to the step response to spontaneous fluctuations in BP. Compared to the uncontrolled hypertension, the normotensive individuals were younger (age 43.42±11.14, P<.05) and had a lower resistance-area product (1.17±0.24, P<.05), although age and greater arteriolar stiffness did not affect the CBFV mean of hypertensive patients, whether controlled or uncontrolled (62.85×58.49×58.30cm/s, P=.29), most likely because their ARIs were not compromised (5.54×5.91×5.88, P=.6). Hypertensive patients under treatment, regardless of their BP control, have intact AR capacity.