An apparatus, a system, and methods for maintaining and monitoring an excised donor heart. The apparatus comprises a first component for receiving and submerging therein an excised heart in a constantly circulating perfusate solution and a second component comprising equipment for adjusting the temperature and oxygen content of the perfusate solution. The first component comprises an integral pair of defibrillating pads. A first conduit infrastructure interconnects the first module, the second module and an aorta of the excised donor heart pushing a perfusion solution from the first module through the second module into the aorta. The second conduit infrastructure connects the first module with the right atrium and the left atrium for pushing the perfusion solution from the first module into the atria. The third conduit infrastructure connects the first module with the pulmonary artery and provides an after pressure to the flow of the perfusion solution from the pulmonary artery.