Dynamics of cardiac atrial fibrillation

The activation patterns that underlie the irregular electrical activity during cardiac atrial fibrillation (AF) have traditionally been described as disorganised or random. Recent clinical and experimental studies have provided evidence that AF is spatially organized. The objective of this study was to identify patterns of wave propagation that demonstrate spatial and temporal order in the atrial tissue during AF in 32 patients suffering from idiopathic AF. We mapped simultaneously both right and left atria with 30 electrodes and, from the analysis of the recorded electrograms, we found: the coexistence of regions with two different stable dynamical patterns in the atrial chambers: one pattern disorganised activations consistent with the presence of several meandering wavelets (pattern B); pattern A was prevalent in patients with paroxysmal AF while pattern B was prevalent in patients with chronic AF. These results, together with our previous findings that radio-frequency ablation by transvenous catheter resulted more effective in patients with paroxysmal AF than in those with chronic AF, suggest that dynamic characterisation of AF may give useful information to `guide` the ablation therapy. Moreover the above findings, that remind some basic dynamical properties of excitable media. provide further evidence that complex arrhythmia is as much a problem in physics and mathematics as it is a medical problem. Further ongoing research is focusing on the many challenges of measuring and analysing simultaneous electrograms from multiple endocardial sites in the clinical setting, analysing detailed re-entrant wave propagation maps in the laboratory and modelling the propagation with suitable sets of non-linear partial differential equations