Serial changes in static and dynamic cerebral autoregulation after acute ischaemic stroke.

BACKGROUND: The longitudinal changes in static and dynamic cerebral autoregulation (CA) following acute ischaemic stroke are unknown and were assessed in this study. METHODS: Fifty-four ischaemic stroke patients were studied within 96 h of ischaemic stroke and again 7-14 days later, using transcranial Doppler techniques to measure CA. Results were compared to an age-, sex- and blood pressure (BP)-matched control group. Static BP pressor stimulus was produced by thigh cuff inflation and dynamic stimulus by rapid thigh cuff release. RESULTS: Dynamic, but not static, CA was globally impaired at initial (mean dynamic CA index 3.9 +/- 3.1 vs. 6.2 +/- 2.3, p < 0.005) and follow-up studies (dynamic CA 3.9 +/- 2.8 vs. 6.2 +/- 2.3, p < 0.01) in stroke patients compared to controls. Static CA was similar in stroke patients and controls and was unchanged during follow-up. CONCLUSIONS: Dynamic, but not static, CA is impaired after acute ischaemic stroke and remains abnormal for at least 1-2 weeks post ictus. These changes are present in both the affected and non-affected hemispheres and are unrelated to previous antihypertensive treatment, baseline BP levels or BP changes after stroke, age or stroke type.

Cardiac baroreceptor sensitivity predicts long-term outcome after acute ischemic stroke.

BACKGROUND AND PURPOSE: The baroreceptor reflex arc is important in the short-term regulation of the cardiovascular system, and small studies have reported impaired cardiac baroreceptor sensitivity (BRS) after acute stroke. However, the prognostic significance of impaired BRS is uncertain. METHODS: One hundred twenty-four patients underwent simultaneous ECG and noninvasive beat-to-beat blood pressure (BP) monitoring within 72 hours of neuroradiologically confirmed acute ischemic stroke. Cardiac BRS was assessed from the combined alpha-index by means of power spectral analysis techniques. Baseline data for acute stroke patients were compared with those of a control group matched for age, sex, and casual BP. Patients were followed up for a median of 1508 days (range, 9 to 2656 days), and outcome was compared between patients with and without impaired BRS. RESULTS: Median BRS values were significantly lower in stroke patients than in controls (5 [interquartile range, 3.5 to 7.4] versus 6.2 [interquartile range, 4.5 to 8.3] ms/mm Hg; P=0.04). Sixty-one (33 male) patients (mean age, 70.2 [SD 10.5] years) had impaired BRS (< or =5.0 ms/mm Hg) compared with 63 (35 male) patients (mean age, 70.6 [SD 11.7] years) without impaired BRS (>5.0 ms/mm Hg). Stroke patients with impaired BRS values had a significantly poorer prognosis (28% versus 8% mortality rate during the follow-up period) although there were no differences in age, stroke severity, stroke type, or casual or 24-hour BP parameters between the 2 groups. CONCLUSIONS: Impaired cardiac BRS is associated with increased long-term mortality after acute ischemic stroke, irrespective of age, sex, stroke type, and BP. This may reflect cardiac arrhythmias, but the mechanisms underlying this association are unknown, although therapies that improve cardiac BRS after stroke warrant further investigation.