A Heartbeat-Interval Time Series Analysis, Modified Detrended Fluctuation Analysis, mDFA, Distinguishes between Stressed- and Happy-Heartbeats: From Invertebrate Animals to Humans

Abstract

This study provides evidence that a time series analysis (modified detrended fluctuation analysis, mDFA) is practically distinguish happy- and stressed hearts. This endures that the scaling exponent (scaling index, SI, or alpha, α) can characterize the state of heartbeats. We learned from various challenges of case studies; for example, the Wolff–Parkinson–White syndrome yields a high SI (way surpass 2.0) while feeling sick condition, but the same heart exhibits a healthy SI (∼1.0) when the heartbeats return to normal. Meantime, a healthy SI (∼1.0) goes down to a low SI (0.7) when truly enjoying meal. It seems that SI can represent invisible internal world. The complex interaction between the cardiac rhythm and the autonomic brain command becomes perceptible by the SI. Our observations confirm the state of the heart is measurable quantitatively. A time series analysis of mDFA can help holistic understanding of the brain-heart axis.