Abstract: Cardiac ventricular assist apparatus adapted to be placed by insertion through an incision in the wall of the upper abdomen below the rib cage and an incision in the inferior aspect of the pericardium proximate the heart apex comprises a distensible flexible bladder adapted to be passed through the incision in the pericardium to a position between the pericardial sac and the epicardium. The bladder is of a size such and shape such as to be engageable with a substantial portion of the outer surface of the left ventricle of a heart and is attached to a tube through which a gas can be introduced into it to compress the left ventricle and withdrawn from it to allow the ventricle to fill. A non-dietensible tube joined to the distal edge of the bladder is connected to a source of a fluid by which it can be inflated after insertion of the bladder to deploy the distal edge of the bladder from a collapsed condition in which it is emplaced within the pericardium to an extended condition partly encircling the heart.