Recovery of autonomic dysfunction assessed by heart rate variability after acute stroke: an observational study

Early mobilisation after acute stroke is recommended worldwide, and autonomic dysfunction is a common complication. However, little is known about autonomic adaptation to postural changes during early mobilisation. The aim of the present study was to clarify the recovery process of autonomic dysfunction after acute stroke regarding adaptation to postural changes. A total of 23 patients (mean age 60 ± 11 years) were included in this observational study. Those with a history of arrhythmia, heart failure and diabetes mellitus with diabetic neuropathy were excluded. Autonomic functions were assessed using heart rate variability. Electrocardiograms were recorded when the patients were lying down, sitting up and then lying back down again for 5 minutes in each position. The indices of heart rate variability, total power, high frequency band and low frequency/high frequency ratio, which correspond to total, parasympathetic and sympathetic activity respectively, were calculated to evaluate participants' autonomic function during the 7 days after the onset of stroke. From days 3 to 7 after stroke onset, the low frequency/high frequency ratio was significantly higher, and the total power and high frequency were reciprocally lower in the sitting position than in the supine position. On day 7, the total power and high frequency were significantly higher while the low frequency/high frequency ratio was lower than the total power and high frequency values that were recorded on the second and third days after stroke. Blood pressure levels and heart rates also changed, corresponding to changes in heart rate variability. The patients' autonomic function, as well as heart rate and blood pressure levels, changed gradually during the first 7 days after onset of stroke. The results could lead to optimised clinical practice in safe early stroke rehabilitation.