1898

James Mackenzie, following disappearance of presystolic (i.e., before beat of the left ventricle, when the mitral valve is still open) murmur (rrrlubb-dup) marked A Dangerous Type of Irregularity in a patient in heart failure. In this patient, it followed recurrent attacks of rheumatic fever, with resulting narrowing of opening between left auricle and left ventricle. This was the discovery of “auricular paralysis,” subsequently dubbed auricular fibrillation by Thomas Lewis (Wilson, 120-125; Mair, 144-147). Lewis’s theory that the condition was caused by muscular fibers of the auricle contracting rapidly and independently of each other was held until 1952, when Prinzmetal and others concluded it originated from a single rapidly discharging ectopic focus rather than from a complete circle of movement around the great veins (Mair, 147).