A mathematical model of the atrioventricular node during atrial fibrillation

The atrioventricular (AV) node plays a crucial role during atrial fibrillation (AF). The aim of this study is to present an AV node model which can be fitted to short-term ECG recordings in order to infer certain AV node characteristics. The proposed model is characterized by: i) the arrival rate of atrial impulses; ii) two different refractory periods, corresponding to dual AV nodal paths; iii) the probability of an atrial impulse choosing either of these pathways; iv) a parameter modeling prolongation of the refractory period due to different physiological reasons. The model was tested on atrial fibrillatory ECGs recorded from 33 patients; the average normalized absolute error between the normalized RR histogram and the estimated model probability density function was 0.0023 ± 0.0016, (20-ms bin size, 0-2 s interval). These preliminary results are encouraging as AV nodal properties can be noninvasively assessed by a set of statistical parameters with a simple electrophysiological interpretation.