How Islam changed medicine

Editor—Majeed comments that Al-Nafis described the pulmonary circulation more than 300 years before William Harvey.¹ Harvey always gets the credit in the West, but I would like to remind readers that Michael Servetus was the first Western writer to describe the pulmonary circulation, in Christianismi Restitutio in 1552, finally printed a year before he was burnt at the stake in Geneva.² Lomas points this out in his article in the same issue of the BMJ.³

Colombo (1516-59) can also lay claim to having made the discovery, in De re anatomica (completed in 1559). It would seem that all three men made the same discovery independently, and for different reasons. Al-Nafis realised the interventricular septum was too thick to allow blood to pass across. Colombo noticed the large blood flow of the pulmonary vein. Servetus realised the importance of the size of the pulmonary artery. Al-Nafis was first, but none developed an understanding to include the concept of a systemic circulation. That was indeed Harvey's discovery.