Atavism is the rare reappearance, in a modern organism, of a trait from a distant evolutionary ancestor. We describe an apparent case of atavism involving a 59-year-old man with chest pain whose coronary circulation and myocardial architecture resembled those of the reptilian heart. The chest pain was attributed to a coronary steal phenomenon. The patient was discharged from the hospital on a heightened regimen of β-blockers, and his symptoms improved significantly. To our knowledge, this is only the 2nd reported clinical case of a human coronary circulation similar to that of reptiles.
The basic anatomy and physiology of the mammalian heart is very different from that of the reptilian heart.3 Unlike mammals, reptiles have a single ventricle responsible for distributing mixed blood to both the systemic and pulmonary circulations, which are not completely separate from each other. Hence, the reptilian heart has been called the “transitional heart.” In poikilothermic (“cold-blooded”) reptiles, the heart has a unique adaptive value that enables the conservation of energy during prolonged hibernation.