The beginnings of cardiac catheterization and the resulting impact on pulmonary medicine.

The early history of cardiac catheterization has many interesting features. First, although it would be natural to assume that the procedure was initiated by cardiologists, two of the three people who shared the Nobel Prize for the discovery were pulmonologists, while the third was a urologist. The primary objective of the pulmonologists André Cournand and Dickinson Richards was to obtain mixed venous blood from the right heart so that they could use the Fick principle to calculate total pulmonary blood flow. Cournand's initial catheterization studies were prompted by his reading of an account by Werner Forssmann, who catheterized himself 12 years before. His bold experiment was one of the most bizarre in medical history. In the earliest studies that followed, Cournand and colleagues first passed catheters into the right atrium, and then into the right ventricle, and finally, the pulmonary artery. At the time, the investigators did not appreciate the significance of the low vascular pressures, nor that what they had done would revolutionize interventional cardiology. Within a year, William Dock predicted that there would be a very low blood flow at the top of the upright lung, and he proposed that this was the cause of the apical localization of pulmonary tuberculosis. The fact that the pulmonary vascular pressures are very low has many implications in lung disease. Cardiac catheterization changed the face of investigative cardiology, and its instigators were awarded the Nobel Prize in 1956.