Assessment of Cardiovascular System Through Cardiovascular Autonomic Reflex Test

Abstract

AbstractOne of the cardiovascular autonomic reflex tests (CART) used to diagnose autonomic dysfunction is the head-up tilt (HUT). Healthy participants had their heart rate variability (HRV) and arterial blood pressure (ABP) measured during a head-up tilt test to better understand the physiological events elicited during the four phases of rapid tilt activity: supine, rapid tilt up (RTUP), at rapid tilt (ATRT), and rapid tilt down (RTDOWN). We analysed the ECG, ABP, and angle data during rapid tilt operation of 10 normal healthy subjects aged (27–32) years using Physionet data. Each data set lasts for one hour. The signals were sampled at a frequency of 250 Hz. We calculated HRV and ABP morphological parameters during HUT. Certain parameters, such as the mean of the standard deviation of average to normal intervals (SDNN), root mean square of successive differences of NN (RMSSD), number of interval differences of successive NN intervals greater than 50 ms (NN50), systolic pressure(SP), pulse pressure (PP), baroreflex sensitivity index (BRS), –HF, and –LF, decrease during ATRT. According to this report, during a head-up tilt test, blood pressure drops in the upper body parts but rises in the lower limbs due to gravitational pooling of blood in the lower limbs. As a result, baroreflex control occurs, which constricts blood vessels and raises HR in order to restore BP.KeywordsBaroreflex sensitivity (BRS)Cardiovascular autonomic reflex test (CART)Head-up tilt test (HUT)Heart rate variability (HRV)Arterial blood pressure (ABP)Rapid tilt down (RTDOWN)Rapid tilt up (RTUP)Heart rate (HR)