Hearts are Poised Near the Edge of Chaos
Abstract
The Cardiac Purkinje Fiber (CPF) is the last branch of the heart conduction system, which is meshed with the normal ventricular myocyte. Purkinje fiber plays a key role in the occurrence of ventricular arrhythmia and maintenance. Does the heart Purkinje fiber cells have the same memory function as the cerebral nerve? In this paper, the cardiac Hodgkin–Huxley equation is taken as the object of study. In particular, we find that the potassium ion-channel K and the sodium ion-channel Na are memristors. We also derive the small-signal equivalent circuits about the equilibrium points of the CPF Hodgkin–Huxley model. According to the principle of local activity, the regions of Locally-Active domain, Edge of Chaos domain and Locally-Passive domain are partitioned under parameters (a,b), and the domain exhibiting the normal human heartbeat frequency range (Goldilocks Zone) is identified. Meanwhile, the Super-Critical Hopf bifurcation of the CPF Hodgkin–Huxley model is identified. Finally, the migration changes between different state domains under external current Iext excitation are analyzed in detail.
All of the above complex nonlinear dynamics are distilled and mapped geometrically into a surreal union of intersecting two-dimensional manifolds, dubbed the Hodgkin–Huxley’smagic roof.
- Edge of chaos
- local activity
- local passivity
- heart beats frequency
- Hodgkin–Huxley model
- cardiac Purkinje fiber
- memristor
- pinched hysteresis loop
- potassium ion-channel
- sodium ion-channel
- small-signal equivalent circuit
- eigenvalue
- Jacobian matrix
- equilibrium point
- external current excitation
- impedance function
- admittance function
- bifurcation