Test di non linearità per la ricerca di un eventuale dinamica caotica nel sistema cardiovascolare

Abstract

In this article we propose a statistical test for detecting nonlinearity in experimental data from cardiovascular system of Bufo Arenarum. Moving from a previous study we analyze the possible chaotic behaviour of Monophasic Actional Potential (MAP) at fibrillation regime. We employ a novel nonlinearity test based on the technique of surrogate data, which makes use of Simulated Annealing. This test avoids the problems associated whit phase randomized surrogates and allows reliable detection of nonlinearity. 
The null hypothesis that data comes from a linear stochastic process monotonically transformed by the observation function is rejected. The results do not  prove that MAP at fibrillation regime is definitely chaotic, but suggest the need of verifying more structured hypotheses.