In a cardiographic apparatus (10), a plurality of electrodes (16) are configured for operative connection with a subject (14). A cardiograph (12, 12′, 12′) is connected with the plurality of electrodes to acquire cardiographic data. A respiratory gate (20, 22, 26, 36, 46, 50, 52, 54) is configured to identify end expiration periods or other quiescent respiratory periods so as to generate a cardiographic dataset (30) limited to the identified end-expiration periods from cardiographic data acquired by the cardiograph at least during the identified end expiration periods.