Abstract: A synthetic intraventricular implant device adapted to be surgically secured in a ventricle of the heart of a patient. The shape, size and volume of the device so inserted will depend on the size of the ventricle of the patient, and how much of the end-diastolic volume thereof it is desired to reduce. The device is surgically inserted into and secured in place in the ventricle by suturing it onto a preselected segment of the interior wall of the ventricle to reduce end-diastolic volume, pressure and wall stress, and to subsequently increase ejection fraction and cardiac output. The device may include a fluid, liquid, semi-liquid, semi-solid, solid or viscous core and/or an inflatable balloon-like portion for use in assisting in the elimination of blood from the "dead volume" within the ventricle.