Effect of Various Agents on the Blood Flow through the Coronary Arteries

Porter sums up the history of the early work on the coronary circulation as follows: In I689, J. Baptiste Scaramenci demonstrated that the vessels were squeezed during systole and filled in diastole. This view was supported by Stroem, in I7o7, with the fact that the aortic valves close the coronary openings during systole. In I855, Hyrtl stated that blood spurted from a cut coronary during systole, and his findings were confirmed by Perls, although they failed to mention which end of the vessel spurted. Klug, in I876, ligated the vessels in diastole and systole and then coagulated the blood. He found a greater quantity present during systole. This earlier work was followed by that of Chaveau and Rebatel who recorded the velocity of flow. They determined that there were two fillings, one in systole and one in diastole. Martin and Sedgwick, in I895, showed that the pulse wave in the coronaries was synchronous with that in the carotid arteries, although they did not deny the possibility of a diastolic filling. In the same year, Martin observed the vagus control of vasodilation in the cardiac vessels. With the introduction of perfusion by Martin, in I89o, there began a great deal of work concerning the effect of various factors on the coronary flow. Magrath and Kennedy, in I897, demonstrated that the strength and not the frequency of the heart was dependent on the amount of coronary circulation. In the following year, Porter demonstrated that the flow is influenced by both the rate and strength of the heart beat. I. Hyde showed that distention of the ventricle diminished coronary flow. Pratt pointed