Abstract
Heart rate variability (HRV) is a significant measure indicating how much variation exists in one’s heartbeats within a specific timeframe. Two important models- the polyvagal theory and neurovisceral integration models and correlation among vagally assessed high-frequency heart-rate variability (HF-HRV) with neurovisceral integration describe the heart rate variability. The neurovisceral integration model explains the role of prefrontal cortex in regulating the limbic structures suppressing parasympathetic and activating sympathetic activities leading to HRV and modulation of HRV. Major methods for analyzing HRV are: a): Time-domain measurement; b): Geometric-measurement methods; c): Frequency-domain methods; and d): Non-linear measurement methods. Increase in vagal functional activity has indeed quite potential involvement. However, there is no clear clue indicating the extent of increase that might be beneficial. There are various cardiac diseases and non-cardiological diseases where decrease in HRV occurs. However, increase in HRV for well-being and normal health can be produced by several factors/ conditions for protective measures. Conclusively, the factors increasing the HRV may provide protection against cardiac disease, mortality and sudden death. However, it seems also important to keep in mind that there might not be always true to assume that too much high modification of HRV may bring cardiac protection.
