The historical period called the Middle Ages, a long interval between the 5th and the 15th centuries, is still commonly known as the Dark Ages, especially in the area of health sciences. In the last decades, this "classic" view of the Middle Ages has been gradually modified with advances in historiographical studies and the history of science. During that period in Western Europe, knowledge about the human body suffered a regression in terms of anatomy and physiology, with the predominance of religious conceptions mainly about diseases and their treatments. Knowledge on the cardiovascular system and heart diseases has been classically described as a repetition of the concepts developed by Galen from the dissection of animals and his keen sense of observation. However, the Middle East, especially Persia, was the birth place of a lot of intellectuals who preserved the ancient knowledge of the Greeks while building new knowledge and practices, especially from the 8th to the 13th century. The invasion of the Arabs in North of Africa and the Iberian Peninsula and the eclosion of the Crusades resulted in a greater contact between the East and the West, which in turn brought on the arrival of the Arab medical knowledge, among others, to 12th century Europe. Such fact contributed to an extremely important change in the scientific medical knowledge in the West, leading to the incorporation of different concepts and practices in the field of cardiovascular Medicine. The new way of teaching and practicing Medicine of the great Arab doctors, together with the teaching hospitals and foundations in the Koran, transformed the Medicine practiced in Europe definitely. The objective of this paper is to describe the knowledge drawn up from the Middle Ages about the cardiovascular system, its understanding and therapeutic approach to cardiologists and cardiovascular surgeons.