(A). A Langendorff perfused heart and 32 multi-electrode arrays was placed on the right atria. (B). Layout of 32 multi-electrode arrays.(C). representative examples of right atrium waveforms and activation during sinus rhythm from a sham rat (left) and a SP (sterile pericarditis) rat on postoperative day 3 (right) analysed by multielectrode array. In contrast to the atrial activation patterns in sham rats, the maps from SP rats were characterized by inhomogeneous conduction.