Sympathetic Afferents and Cardiac Pain.We analyzed some particular aspects of the peripheral pathways likely to be involved in the mediation of cardiac pain. The functional characteristics and the reflex function of cardiac sympathetic afferent fibers are discussed in relation to the afferent code transmitting nociception. A modified version of the intensity theory based on the extreme excitation of a spatially restricted population of afferent sympathetic fibers is proposed as the most likely mechanism involved in the genesis of cardiac pain.