Figure 5 : The CardioWest Total Artificial Heart. It is a biventricular, pneumatic, pulsatile blood pump that completely replaces the patient's native ventricles and all four cardiac valves orthotopically. It weighs 160 g. It is lined with polyurethane and has a four-layer, pneumatically driven diaphragm. At maximal stroke volume (70 ml), it delivers a cardiac output of more than 9 liters per minute. In the United States, the device is powered by a large console on wheels that prevents hospital discharge; portable drivers permitting discharge from the hospital are currently used in Europe. The device may be useful in patients for whom left ventricular assist devices and biventricular assist devices are contraindicated, including those with aortic regurgitation, cardiac arrhythmias, a left ventricular thrombus, an aortic prosthesis, an acquired ventricular septal defect, or irreversible biventricular failure requiring high pump outputs.