Mapping activation in a sinoatrial node cardiac tissue preparation with a multi-electrode array

An isolated rabbit cardiac sinoatrial node (SAN) tissue preparation was used experimentally to map activation times and conduction velocities of extracellular cardiac action potential (AP) propagation. Extracellular recordings were carried out using a two-dimensional array of unipolar Ag-AgCl microelectrodes connected to a 128-channel data acquisition system. A 20^th order, low-pass Butterworth filter, with a cut-off frequency of 50 Hz, was used in conjunction with a Matlab algorithm to map activation times and conduction velocities. Results show an initial slow-down of the activation wavefront emanating from the SAN, followed by acceleration in some regions, particularly near the Superior Vena Cava, as it travels towards the SAN periphery.