This paper studies the possibility of heart kinetic motion for designing a self-powered intracardiac leadless pacemaker by piezoelectric energy harvesting. A Doppler laser displacement sensor measures in vivo heart kinetic motion. Cantilevered and four-point bending piezoelectric harvesters are studied under the measured in vivo heart kinetic motion. The heart movement is above 15 mm. The cantilevered and four-point bending harvesters generate a maximum voltage of ~ 0.28 V and 0.8 V, respectively with the measured heart motion with a heart rate of 168 beats per minute. Two DC/DC converters, LTC3588 and MAX17220, combined with full-bridge rectifiers and their start-up performance are tested.Clinical Relevance-This paper analyzed the heart kinetic motion and establishes the piezoelectric energy harvesting for a new era of self-powered leadless pacemakers.