Abstract: An isolated heart or heart-lung preparation in which essentially normal pumping activity of all four chambers of the heart is preserved, allowing for the use of the preparation in conjunction with investigations of electrode leads, catheters, ablation methods, cardiac implants and other medical devices intended to be used in or on a beating heart. The system can be designed to be used within a Magnetic Resonance Imaging (MRI) unit or a X-ray computed tomography (CT) scanner. The preparation may also be employed to investigate heart and lung functions, in the presence or absence of such medical devices. In order to allow comparative imaging visualizations of either or simultaneously the heart and/or lung structures and devices located within the chambers of the heart or vessels or bronchi within the lungs, a clear perfusate such as a modified Krebs buffer solution with oxygenation is circulated through all four chambers of the heart and thus the coronary and/or pulmonary vasculatures.