Heart Rate Variability (HRV) biofeedback is psycho- physiological measurement (Heart Rate-ECG, Blood Pressure, and Respiration) to diagnose autonomic regulation, stress resistance, cardiovascular health, and vitality in persons. Heart Rate Variability (HRV) means changes in the interval or distance between one beat of the heart and the next. The interbeat interval (IBI) is the time between one R-wave (or heart beat) and the next, in milliseconds. The IBI is highly variable within any given time period. HRV is analyzed in two ways, either over time (Time Domain) or in terms of the frequency of changes in Heart Rate (Frequency Domain).

