Disclosed is a method of preserving a heart ex-vivo. The method includes placing a heart in a protective chamber of a portable organ care system and delivering a pulsatile flow of perfusion fluid to the heart with a pump. The perfusion fluid is at a temperature of between 25 °C and 37 °C and at a volume flow rate of between 200 ml/min and 5 L/min. The method also includes measuring with a sensor one or more physiologic characteristics of the heart while it is beating, and operating the pump in response to the one or more physiologic characteristics. The step of operating the pump includes timing the pulsatile flow so the perfusion fluid enters the heart when the heart is in a diastolic state.
