Heart rate and blood pressure variability among hypertensive and normotensive patients with acute thrombotic stroke: clinical relevance and implications

ABSTRACT

This study was aimed to assess the circadian changes in the blood pressure, heart rate variability and the circadian changes of cortisol level in normotensive as well as hypertensive patients with acute thrombotic stroke to determine whether there is abnormality or not in their diurnal changes and their relation to stroke severity. The heart rate variability [time domain and frequency domain] from 24-hour ECG recordings were analyzed in 30 patients with first acute ischemic stroke [within 24 hours of onset]. Eighteen were known hypertensives and 12 were normotensives. Brain C-T scan and NIHSS were done after admission. Patients were monitored with a bedside monitor for 24 hours to assess blood pressure every 15 minutes and blood cortisol level was measured every 6 hours. The parasympathetic oscillation, the diastolic and mean blood pressure variability indices were reduced in hypertensive patients than normotensives. However, in the late night the parasympathetic oscillation increased in hypertensives but tend to be reduced in normotensives. Increasing in sympathetic daily variation and reduced systolic blood pressure variation were associated with increasing in the stroke severity in normotensives, but decreasing in parasympathetic daily changes were associated with increasing the stroke severity in both groups. Hypertension seemed to cause significant changes of the cardiovascular autonomic regulatory system manifested as abnormalities of heart rate and diastolic pressure variability [especially late night]. The stroke severity was increased with reduced diurnal changes of parasympathetic fluxes in both normotensives and hypertensives and excess sympathetic daily fluctuations in normotensives