An endocardial heart function intervention device that optimizes the cardiac geometry in patients with heart failure. The device comprises one or more elastic elements sutured in place within a heart that will establish radial elasticity in a direction towards the inside of the ventricle and plastic deformation in a direction that is transversal to the ventricle and is configured to be adjusted axially and radially to and along a section of the endocardial wall while in a neutral rest condition and can thereafter expand to receive energy from the endocardial wall during the diastolic phase, to cede energy received to the endocardial wall during a systolic phase.