The cardiovascular system is regulated by the autonomic nervous system, under cortical modulation. Stroke can induce cardiac autonomic imbalance, therefore, causing secondary cardiovascular complications. Heart rate variability (HRV) analysis is a simple method to appraise the autonomic nervous function. The purpose of this study was to investigate the cardiac autonomic activity in patients that suffered an ischemic stroke in middle cerebral artery (MCA) territory. Using Biopac Acquisition System, we monitored ECG in rest condition and during Ewing's tests. From these measurements, HRV parameters (using time and frequency domain analysis) were determined in 20 right MCA and 20 left MCA ischemic stroke patients, in the first 6 months after the acute event. Data were compared with 20 age- and sex-matched healthy controls. All the patients were right handed. In ischemic stroke patients, HRV parameters were significantly modified compared to controls (p < 0.05) and we found asymmetric responses to different stimulation autonomic tests between right and left hemisphere. Parameters illustrating the parasympathetic predominance in time domain (RMSSD) and frequency domain (HF) analysis were higher in left hemisphere stroke compared to right hemisphere stroke patients (p < 0.01) in resting state. From Ewing's battery test, patients with left hemisphere ischemic stroke showed predominance of parasympathetic activity to deep breathing (p < 0.01), while HRV parameters in right hemisphere ischemic stroke patients described a reduced cardiac parasympathetic innervation (p < 0.01). Cardiac autonomic imbalance occurs more often after right hemisphere ischemic stroke. HRV study may highlight cardiac dysfunctions that increase the risk of cardiovascular complications and portends a poor long-term outcome.
Keywords: Autonomic cardiac dysfunction; Heart rate variability; Ischemic stroke.