An implantable ventricular assist device comprises an intraventricular stent used for the creation of an artificial chamber inside the ventricle, a balloon-like structure used to drive the change of the artificial chamber between a contractile configuration and a diastolic configuration, a power system used for driving the change of the balloon-like structure between the contractile configuration and the diastolic configuration. There is also a power system and a mechanical design to operate the system working, wherein in the contractile configuration, the balloon-like structure expands and occupies the space of the artificial chamber and drives the blood inside the artificial chamber flow outside the artificial chamber, wherein in the diastolic configuration, the balloon-like structure shrinks and releases the space inside the artificial chamber, and the blood outside the artificial chamber flows back into the artificial chamber. It is easy to reach the goal of cardiac function.