Effect of head up tilt on heart rate variability in males

Keywords: Head up tilt(HUT) Heart rate variability(HRV) Low frequency(LF) High frequency(HF) Original Article AIMS : Orthostatic stress is commonly utilized to evaluate the cardiovascular autonomic function. This is done mainly by Head Up Tilt (HUT) testing. The parameters which represent the cardiovascular autonomic function involved the Heart Rate Variability (HRV).HRV indices provide non-invasive assessment of cardiovascular control mechanisms. Low Frequency (LF) is an indicator of sympathetic system. High Frequency (HF), an index of parasympathetic and the ratio LF/HF is the specific and quantitative index of sympathovagal balances. MATERIALS AND METHODS : Hundred apparently healthy males in the age group of 18-45 years were selected to evaluate the effect of HUT on cardiovascular autonomic responses. Parameters of HRV were recorded at supine and 300, 600 and 800 HUT. Niviquire software was used to measure the LF, HF and the LF/HF ratio. In each position the Heart Rate (HR) was determined by recording the ECG for 5 min in lead II. RESULTS: LF and the LF/HF ratio increased on HUT in males and HF decreased on HUT. CONCLUSION: Cardiovascular reflex effects can be assessed using various postural stress tests effectively for physiological and clinical investigations in the field, by the patient bed side, or in the laboratory using more elaborate equipment. HRV is one among them. With HUT the sympathetic activity increases and parasympathetic activity decreases.