The cardiovascular system, as understood in antiquity

Abstract

Cardiovascular concepts in antiquity were primitive up to the early 5th century BC, when Greek philosopher-physicians like Empedocles and Diogenes divorced human physiology from its previous magico-religious base in order to find answers in the natural sciences. The heart was not initially seen as central to the cardiovascular system – blood (containing life-giving pneuma) moved through the body in blood vessels (phlebes) by way of a spontaneous “ebb and flow” motion. Their perceived anatomical vascular models were quite fanciful, but nevertheless accepted by the Hippocratic doctors, who, except for a single work, The heart (containing a useful description of the heart), added little of significance to the subject. Based on animal dissections, post-Hippocratic authors like Diocles and Praxagoras first distinguished between arteries and veins, confirmed that the heart had two main chambers (ventricles) and extended the theory that “innate heat” in the left ventricle produced pneuma which filled the arteries; only veins contained blood, produced in the right ventricle. Basing their theories on human dissections the Alexandrians, Herophilus and Erasistratus (3rd century BC) produced the first accurate descriptions of the heart and major components of the vascular system. Erasistratus even postulated minute (normally non-functional) peripheral arterio-venous anastomoses. The heart’s pump function was only partially understood – diastole was seen as the active phase of the cardiac cycle (sucking blood into the heart), and the pulse as inherent contraction of the arterial wall. After Herophilus and Erasistratus human dissection ceased, putting an end to further significant developments in unravelling the cardiovascular system. In the 2nd century AD, Celsus consolidated known knowledge, even adding minor contributions (e.g. a description of the coronary vessels) based on his own animal dissections. He mainly confirmed the Alexandrians’ findings and contemporary views on cardiac function, including inherent arterial pulsation, “ebb and flow” blood movement in veins, and the existence of pneuma. He claimed that arteries contained blood, not  pneuma. These views, as well an erroneous personal contribution (that there were minute pores in the heart’s interventricular septum), remained medical dogma throughout the Middle Ages up to the Renaissance.