Embodiments of the invention provide apparatus, systems and methods for harvesting energy from bio-kinetic events to power various implanted medical devices. One embodiment provides an energy harvesting mechanism for a cardiac pacemaker comprising an energy converter and a signal path component. The energy converter is positionable inside a human body and configured to generate electric power signals in response to a bio-kinetic event of the human body such as a heart beat, respiration or arterial pulse. The converter can comprise a piezoelectric material which generates electricity in response to mechanical deformation of the converter. The converter can also have a power generation characteristic that is matched to the frequency of the bio-kinetic event. For heart beat powered applications, the power generation characteristic can be matched to the physiologic range of pulse rates.