In 1895, Oscar Langendorff was the first to produce an isolated mammalian heart with full contractile activity. Since that first experiment, the method of Langendorff has been a pillar in cardiac research leading to major advancements in the field of cardiology. The basic goal of the Langendorff method is to provide an isolated heart with oxygen and metabolites via a single cannula inserted into the ascending aorta. Oxygenated blood or a perfusate is pumped down the aorta towards the heart by means of an external pump. This constant 'retrograde' perfusion of the aorta keeps the aortic valve closed and allows for fluid flow into the coronary arteries during the diastolic period, just as it flows in the normal cardiac cycle. Fluid (buffer) movement continues through the coronary system (left and right main coronaries -> arterial braches -> arteriole -> capilaries -> venilles -> coronary veins) and eventually exits via the coronary sinus in the right atrium. Approximate coronary flows required for a large mammalian heart range between 0.5 - 1.5 Liters/min.

Throughout this procedure, the left chambers of the heart remain filled and the ventricles contract, but with out fluid exchange (no flow). Since the force of contraction is proportional to the pressure inside the ventricles (Frank-Starling principle), many researchers have attempted to pressurize the left ventricle to create a more physiological contraction. For example, inflated balloons have been placed in the ventricles to increase the ventricular pressure and the force of contraction. Similarly, pressures have been created by filling the ventricles with fluid and using an atrioventricular clamp to prevent valvular regurgitation, as is done in our laboratory.

Initially, the Visible Heart preparation relies on constant pressure Langendorff perfusion to supply the myocardium with adequate oxygen and metabolites that may have been depleted during explantation. However, once normal sinus rhythm has been sustained without the presence of major arrhythmias, the heart can be transitioned into 4 chamber working mode and Langendorff perfusion stopped or re-established as desired.