A cardiac event microrecorder comprising a hermetically sealed housing is shaped and dimensioned to facilitate the subcutaneous implantation of the microrecorder in a human patient by injection through the lumen of a hypodermic needle. The housing comprises a tubular central section of an electrically insulating material, the central section having spaced apart extremities. An electrically conductive sense electrode is secured to and seals each extremity. The housing may have an interior enclosing (1) electrical circuitry for processing, storing and telemetering data representing physiologic information detected by the sense electrodes; (2) a primary cell or rechargeable battery for electrically powering the electrical circuitry; and (3) an inductively couplable charger where a rechargeable battery is used. Also disclosed are a method of subcutaneously implanting a cardiac event recorder in a patient's thoracic region, and a handheld mapping device for determining an optimum location and orientation for the cardiac event microrecorder to be implanted.