A process for assisting the function of a heart disposed within a body, and comprising an outer wall, comprising the steps of measuring at least one parameter that is indicative of the function of the heart, applying a compressive force to a portion of the outer wall of the heart, and applying an expansive force to the portion of the outer wall of the heart. The process is preferably performed with an apparatus comprising a cup-shaped shell having an exterior wall, an interior wall, an apex, and an upper edge; a liner having an outer surface and an inner surface, an upper edge joined to said interior wall of the cup-shaped shell, and a lower edge joined of the interior wall of the cup-shaped shell, thereby forming a cavity between the outer surface thereof and the interior wall of the shell; and a drive fluid cyclically interposed within the cavity, the drive fluid applying a uniform force on a portion of the outer wall of the heart.