Scaling Exponent Determined by a Bio-Signal Computation for the Healthy and Diseased Heartbeat

We analyzed heartbeat-intervals by using our own program of detrended fluctuation analysis (DFA). "Alternans" is an arrhythmia exhibiting alternating amplitude or alternating interval from heartbeat to heartbeat, which was first described in 1872 by Traube. Recently, alternans was finally recognized as the harbinger of a cardiac disease because physicians noticed that an ischemic heart exhibits alternans. To quantify irregularity of the heartbeat including alternans, we used the DFA and revealed that the alternans rhythm lowers the scaling exponent. We conclude that the scaling exponent calculated by the DFA reflects a risk for the "failing" heart. The scaling exponents could determine whether the subjects are under sick or healthy conditions on the basis of cardiac physiology