Philosopher, pediatrician, pathologist? John Locke's thoughts on Rhicketts and a missed case of Ebstein's anomaly.

John Locke (1632-1704) is primarily remembered for his highly influential philosophical works regarded as the engine of the Enlightenment. It is less well known that Locke also was a highly regarded and influential physician. In 1666, Locke performed a postmortem examination of an 18-month-old child who had physical signs of rickets. Locke, a medical student at this time, attributed rickets as the cause of death. However, Locke described and recognized severe cardiac abnormality and speculated that right-to-left interatrial shunting was part of rickets. Locke's clearly described clinical history and postmortem findings are more consistent with a congenital cardiac malformation, an Ebstein's anomaly, in addition to the rickets. Locke did not consider this case as other than rickets. His opinion was not challenged when the case report was re-presented in the past half century. This article forces a reevaluation of the 17th-century understanding of infant cardiovascular physiology and pathology: Locke clearly gives one of the earliest descriptions of right-to-left shunting through the patent foramen ovale. It is unfortunate that Locke apparently did not discuss his postmortem findings with his contemporary Richard Lower (1631-1691), whose celebrated masterpiece on the heart, Tractatus de Corde, was published in 1669.