The CardioCMOS system has been used to make the following recording:

Guinea pig in VF caused by coronary block induced ischemia.  The heart was perfused retrogradely with Tyrode solution heated to 37 C through the aorta on a Langendorff perfusion apparatus and was stained with calcium indicator rhod-2.  The perfusate contained 20 mM DAM (diacetyl monoxime) to inhibit motion. See movie here Provided by Seong-min Hwang, PhD of the Department of Cell Biology and Physiology at the University of Pittsburgh School of Medicine