Detrended fluctuation analysis of atrial signal during adrenergic activation in atrial fibrillation

Aim of the study was to assess the effect of the adrenergic stimulation on the dynamic of atrial signals (AS) during atrial fibrillation (AF). The AS, derived from surface ECG after having removed ventricular activity, were analyzed using the detrended fluctuation analysis. A sympathomimetic drug, the isoproterenol mimicking adrenergic activation, was administered in 13 patients with paroxysmal or persistent AF. Two situations were compared i) AF and ii) AF during isoproterenol administration (AFISO). The existence of two scaling regions in the AS has been documented in most of the recordings through the estimation of the scaling exponents (a₁ and a₂) and the crossover point (nCP). Adrenergic activation seems not to alter highly the correlation properties of the process. However, the crossover point is located at lower scales after isoproterenol infusion.