Late in 1945, Dr. Blalock asked Dr. Richard J. Bing to establish a laboratory to study cardiac physiology. I knew very little of the mechanics of the arrangement, but Dr. Bing and I had fairly close contact. We became good friends while he was setting up the laboratory for the cardiac catheterizations he had planned. The day came when he had his fluoroscopic table on Halsted 3, and the Van Slyke-Neill manometric apparatus for blood-gas determinations (see fig. 24). He had a patient scheduled and asked if I would like to assist him in performing a cardiac catheterization. I told him I would be happy to do so. The nearest I had come to performing cardiac catheterizations was in dogs, in the collection of blood from the right ventricle with the use of a long glass cannula inserted through the external jugular vein in our experimental studies. Plastic tubing had not come into being at that time. The patient, a four- or five-year-old boy, had been sedated. When we were ready to begin, Dr. Bing suggested that I do the cut-down, saying I, not he, was a surgeon. I accepted his suggestion and proceeded with the cut-down, incised the vein at the inner elbow, passed the catheter a few centimeters into the basilic vein, tightened the ligature around the catheter, and turned the procedure over to him. With both of us watching the fluoroscopic screen, he gently advanced the catheter up the arm until the tip came into view on the screen in the left innominate vein. We then watched as the catheter passed downward through the superior vena cava and into the right aurical. Everything to this point was going as expected. The catheter was supposed to follow the flow of blood from the right auricle to the right ventricle, making a sharp 180-degree turn at the apex of the right ventricle, thence passing into the pulmonary artery. The catheter, as it was advanced, instead of following the expected course, took an abrupt go-degree left turn from the right auricle and went directly out into the left lung field. We stopped dead still. In the darkened fluoroscopic room, it was difficult to see each other, but I think both of us had broken into a cold sweat. Gently pulling the catheter back into the right auricle, we waited a minute or two and asked the patient if he felt all right.
When the catheter was very gently advanced again, it took the same direction as before. Dr. Bing decided that we should take air-free blood samples for oxygen determination with the tip of the catheter in several