Special Communication: Looking Back on the Birth and Early Days of Interventional Radiology: Reflections of Dr. Stanley Baum

The past half-century has seen interventional radiology's (IR) transformation from an outgrowth of diagnostic angiography to the vital component of the healthcare system it is today. ^{1 2} The clinical discipline of IR continues to innovate, decrease risk, and improve patient outcomes through its solutions to complex medical problems. ¹ The robust clinical specialty as we know it today would not exist without the key group of luminaries who had the courage and foresight to push the boundaries of medicine. Most of the founding luminaries have since passed, including Dr. Sven Seldinger, Dr. Charles Dotter, Dr. Andreas Grunzig, Dr. Josef Rosch, Dr. Herbert L. Abrams, and Dr. Melvin Judkins. ³ Few luminaries remain who harbored IRs birth. This essay recounts an interview with Dr. Stanley Baum as he describes his participation in the advent of interventional radiology.

A Love for Patient Care

Dr. Stanley Baum decided he did not belong in radiology during the latter half of his residency at the University of Pennsylvania in the late 1950s. Dr. Baum was prompted to enter the field of radiology after working as an X-ray technician during medical school in the mid-1950s, but later decided he did not enjoy being isolated from patients and looking at films only in relation to how they relate to a patient's disease. It was the dissatisfaction with the lack of patient interaction found in diagnostic radiology at the time, combined with his forward thinking that spurred Dr. Baum to branch away from the reading room and enter the hospital floor.

Fascination with the Work from Europe

When Dr. Baum completed a fellowship in diagnostic angiography at Stanford University in 1963, percutaneous selective angiography was an exciting field being cultivated in Europe with outgrowths in North America. He studied percutaneous angiography with Dr. Herbert Abrams who helped bring this technique to the United States from Sweden, where it was first developed in the 1950s and refined in the 1960s. ⁴ To that point, it was previously possible only to navigate a catheter into the endovascular space through invasive arterial cutdown and lumbar punctures. With the advent of the Seldinger technique, the young Dr. Baum was fascinated by the potential to image any organ of the body by the percutaneous introduction of a catheter. Furthermore, it offered the perfect marriage between performing patient-facing studies and being directly involved with patient care.

True Medical Pioneer

The defining moments that gave birth to interventional radiology saw the angiographic catheter transform from a diagnostic to a therapeutic tool. ⁵ Dr. Charles Dotter's use of the angiographic catheter to increase blood flow in patients with occlusive peripheral arterial disease in 1964 and Dr. Baum's application of the angiographic catheter to stop gastrointestinal bleeding in 1967 mark pivotal breakthroughs. ^{5 6 7} Before his intervention to stop gastrointestinal bleeding, Dr. Baum and his surgical colleague Dr. Moreye Nusbaum demonstrated a method for identifying the site of gastrointestinal bleeding via the selective arteriography extravasation of contrast in 1963. ⁸ At that time mortality from acute gastrointestinal bleeding approached 50% when operating on patients with massive bleeds, as there was no way to determine the origin of the bleeding; the flexible endoscope and colonoscopy were not yet being used in clinical care. Armed with angiography skills honed at Stanford, Dr. Baum partnered with Dr. Nusbaum and recalls thinking, “If I can get a catheter into the superior mesenteric artery (SMA) noninvasively in a patient with active gastrointestinal bleeding perhaps I can identify the bleeding site without the surgeon having to do an exploratory laparotomy.” The two pioneers completed a series of animal experiments where Dr. Nusbaum created a bleeding point in the small intestine and Dr. Baum later injected contrast following a selective superior mesentery arteriogram. “We were able to titrate the amount of bleeding by simply changing the diameter of the catheter,” recounts Dr. Baum, “We determined that by using this technique we could actually detect a bleeding rate of 0.5 mL/min.”

The investigators shared the experimental results with a gastroenterologist at the hospital. Dr. Baum recounts a subsequent phone call he received from a gastroenterologist late one evening regarding a patient with massive rectal bleeding. “Remember those studies you showed me on the animals? Do you think you can do an SMA arteriogram on this patient?” He performed the arteriogram and demonstrated a massive bleeding site from a branch of the right colic artery. Knowing the site of bleeding, the surgeon was able to selectively resect that segment of the right colon. The resected portion of the colon contained a bleeding diverticulum.

Around the same time, gastroenterologists in Europe had been injecting vasopressin intravenously to treat variceal bleeding. Because the dose of intravenous vasopressin needed to stop the bleeding was very high, there were significant adverse systemic side effects. ⁹ Given the success of his angiographic localization of gastrointestinal bleeding, Dr. Baum postulated that if a vasoconstrictor could be infused selectively through a catheter after the bleeding site was identified, the bleeding could be stopped. In 1967, Drs. Baum and Nusbaum again conducted animal studies, where vasopressin and other vasoconstrictors were tested and determined to be able to stop gastrointestinal bleeding. Of the agents tested, only vasopressin did not exhibit tachyphylaxis. Shortly thereafter, a patient with a massively bleeding ascending colon diverticulum presented to the hospital. They told the gastroenterologist of their success in the animal model and obtained informed consent from the patient to proceed. “Sure enough,” Dr. Baum recalls, “we were able to stop the bleeding. We kept the [vasopressin] infusion going for about 24 hours until the diverticulum and artery healed. We took the catheter out and the patient never bled again.”

Growing Pains

“Radiologists weren't particularly interested in these techniques because not only did they have to be on call and come in the middle of the night, they had to put the catheters in, monitor those catheters when the patients went back to the floors, and had to make rounds. Radiologists didn't go into radiology to do that.” Dr. Baum describes that most of his early presentations were to gastrointestinal societies and to surgeons. Because of that, Dr. Baum recalls, the surgeons would go back to their institutions and say, “Hey, we heard radiologists at the University of Pennsylvania were actually able to control bleeding by infusing this vasoconstrictor.” They began to press their radiology departments to hire someone who had such a skillset.

Interventional radiology is now known as a robust clinical specialty with its own integrated residency training pathway. However, acceptance for radiologists performing interventional procedures was not automatic. Dr. Baum describes the situation during the early days as IR grew. “You have to realize that most hospitals at the time did not have admitting privileges for radiologists. As a result, radiologists were not encouraged to write notes on a patient's chart. If you wrote a note, you had to have it cosigned by a ‘real physician.’” He cites this as becoming progressively problematic as interventional procedures began to require the radiologist's clinical as well as procedural involvement. Radiologists could not admit patients, but the procedures they began performing required seeing the patient the previous evening to assess anatomy, vessel patency, renal function, volume status, and making sure their day of procedure meal was held. Post-procedurally, Dr. Baum describes, other physicians had little knowledge of these new interventional procedures, and the early interventional radiologists did not want other physicians involved with their patient's follow-up. As per Dr. Baum, “All of this suddenly took the radiologists out of the reading room and brought the radiologists up to the hospital floors as real physicians.” He recalls that at the Massachusetts General Hospital in the mid-1970s, it was not unusual to have six or seven patients being infused with vasoconstrictors at the same time because of gastrointestinal bleeding.

“It Was Very Primitive, But It Worked”

Before catheters became commercially available, Dr. Baum describes how the tools of the trade were being created. He recounted a Swedish-made Odman radiopaque catheter developed for other purposes that came in a roll; three sizes, color coded red, green, and yellow, which were available up to 20 gauge. These catheters needed to be modified for each specific application. As he recounted, “Every catheter was handmade by the angiographer. You would take the catheter, hold it over a flame and pull it to give it a nice, tapered tip on one end. Then you would hold it over a flame again and flange the other end and that would be the part that would have the connector on it. Then you would put it in some sterile solution overnight. If you were lucky your institution had gas sterilization so you could sterilize it.” However, these were all straight catheters, but when used for angiographic purposes they would need to be shaped to various anatomic contours. Catheters were often handmade the evening prior to the procedure and lengths were measured based on the patient's surface anatomy. “If you want to get into the renal artery, you need a right angle from the aorta. If you wanted to get into the SMA, you needed something that almost backed on itself. We would take those catheters and put them in boiling water and form the shape we wanted. That's how bizarre it was at the time.”

Sharing Experiences—The Angio Club

Dr. Baum describes the exciting time during the early days of IR when other local Philadelphia angiographers began to get involved. He, Dr. Sidney Wallace at Thomas Jefferson University, and Dr. Constantine Cope at Einstein Medical Center began meeting monthly to share cases and frankly discuss complications. These meetings, later known as the Philadelphia Angio Club, slowly attracted more members as the applications of angiographic catheters expanded. Similar Angio Clubs sprang up around the country; Dr. Baum described, “We had these individual clubs and sometimes we should have a joint meeting. The New England one would come down to Philadelphia, or we'd go up there. One club became two clubs, then three clubs. That is how we were able to communicate with each other.” Dr. Baum continued to manage the merger of regional angio clubs to eventually help found the Society of Cardiovascular and Interventional Radiology, known today as the Society of Interventional Radiology.

Conclusion

What began in part as an unconventional method for locating and treating gastrointestinal bleeds in the 1960s has since grown into the modern specialty of interventional radiology. In order for the next generation of interventional radiologists to fully appreciate the impact and scope of the field tasked to carry into the future, the birth and early days of this specialty must be understood and appreciated. Although many aspects of the field have since changed, the same principles apply: forward thinking people developing innovative techniques to revolutionize the face of healthcare.