A comprehensive model describing conduction through the atrioventricular node

An algorithm which models conduction over two conduction pathways through the atrioventricular (AV) node has been derived and tested. Output from the node has been previously related to input, the coupling intervals of extrastimuli introduced during programmed atrial stimulation. An exponential model of conduction in a single pathway was used with the general form: A2 H2 = K1 + K2 exp (-A1 A2/K3) with K1, K2, K3 parameters The algorithm for identification of dual pathways minimised residual sums of squares from two such functions. Potential 'bifurcation' points were selected by significant deviation of the computed single curve of best fit. The algorithm was tested using data obtained during electrophysiology study. Three trials of programmed stimulation were performed in 15 patients after pacing at 100 bpm. Computations using the model suggested single and dual functions (and therefore pathways) respectively in 19 and 25 of 44 trials. An electrophysiologist independently examining the data usually agreed (83% of trials). As the reasons for discordance were minor the model was reasonably verified.