Figure 1: Representation of the one-atrium one-ventricle heart preparation. (a) Schematic representation of a one-atrium one-ventricle heart, the contractility of both being determined by their diastolic distension. If it is contracting, flow is unidirectional due to both valves, the “mitral” and “aortic” valves. This one-atrium one-ventricle heart is attached to an artificial circulation, set up by three sections: (1) an elastic “arterial” high-pressure section, (2) a “peripheral,” variable resistance section, and (3) a “venous” low-pressure section. (b) Schematic representation of the EEC simulating the properties of a one-atrium one-ventricle heart attached to an artificial circulation. Current (equivalent to blood flow) is measured at the end of the “venous” section because at this point of the circuit pulsations of the current are minimal.