Cardiac fibrillation : an interdisciplinary puzzle

Cardiac fibrillation affects the atria or the ventricles and, in both cases, poses major challenges to public health management. Atrial fibrillation is the predominant cause of embolic stroke while ventricular fibrillation is another word for sudden cardiac death. The medical community of cardiac electrophysiologists consider cardiac fibrillation as a disease of known cause but of unknown trigger, the targeting of which solves the riddle by a combined therapy of anti-arrhythmic drugs and catheter ablation.
However the rate of failure is in fact much higher than success. In a recent work (10.3389/fphys.2017.01139 and 10.3389/fphys.2019.00480), we have provided evidence and modeling which seem to clash with the accepted wisdom. Reviewing historical concepts, I will outline the difficulty to assess the random multifractal dynamics revealed in recordings of the electrical activity of fibrillating human hearts without questioning the conducting substrate. In this respect, I will present a cardiac excitable cell network modeling of abnormal capacitive charging at the electrical synapses (gap junction channels), which accounts quantitatively well for the observed dynamical property in a specific region of the heart. The model implies that bits of information in beat recording have been missed so far, profoundly impacting their interpretation. To be validated, those new observations and modeling raise a number of challenges that span various aspects that I will discuss, such as protein expression and transport in cells, or front propagation in random media. They also open avenues for the discrimination of classes of diseases that underlie cardiac fibrillation as only a symptom.