Back to Table of Contents | December 2009

Cover Story

Intervening Specialists

With increasingly sophisticated tools threaded through catheters, interventional radiologists are bringing new treatments to some of the body’s hardest-to-reach sites.

By Kate Ledger

When the 70-year-old man was rushed to an ER in St. Paul recently, he was already showing dramatic signs of what was likely a stroke. Not only had he lost the ability to move the right side of his body, he was unable to speak and could no longer comprehend what was being said to him. In the cath lab, interventional neuroradiologist Michael Madison, M.D., confirmed the diagnosis with an angiogram: The man had a critical narrowing of the left carotid artery in his neck that led to the formation of a clot that then embolized and blocked blood flow to the left middle cerebral artery. “A large part of the left side of his brain was at risk of dying,” Madison says.

Until recently, the only potential treatment would have been to give the man an intravenous dose of the blood-thinning drug tPA. Giving IV tPA for patients with large-vessel strokes, however, reopens the blood vessel only 15 or 20 percent of the time, says Madison, a partner with St. Paul Radiology, a large privately held group.

But Madison had new tools at his disposal to give the patient a better shot at recovery. With fluoroscopic guidance, he initially threaded an angioplasty balloon from the patient’s groin up into the left carotid artery and inflated it to widen the part of the vessel that had narrowed. Then, he used a microcatheter to access the occluded left middle cerebral artery and administered tPA directly into the clot to dissolve it.

Like others in the field of interventional radiology, Madison belongs to one of the fastest-changing specialties in medicine. With a host of minimally invasive procedures at their disposal, interventional radiologists can not only offer the opportunity to visualize hard-to-reach pathologies but, increasingly, they can treat them.

In fact, the field as a whole has evolved so much in recent years, “even some [referring] doctors aren’t aware of all the latest tools and what we’re now able to do,” Madison says. Long considered essential but behind-the-scenes players, interventional radiologists are offering an array of new frontline procedures for an ever-widening range of conditions. And they’re transforming the specialty by taking on a new role in patient care as well.

Reaching Remote Places

The fundamental technique used in interventional radiology—the threading of catheters through blood vessels under the guidance of X-ray imaging—dates back to the 1920s. But the field of interventional radiology really got its start in 1964 when University of Oregon radiologist Charles Dotter, M.D., used a balloon catheter guided by fluoroscopy to widen the vessels in and restore blood flow to the infected foot of an 83-year-old woman, sparing it from amputation. He was nominated for a Nobel Prize in 1978, after having clearly spurred a revolution in medicine.

By the end of the 1960s, the use of minimally invasive diagnostic and therapeutic procedures was burgeoning. Suddenly, image-guided endovascular catheters were being used to access and treat all sorts of pathologies. Physicians were using catheters to embolize the blood vessels feeding tumors to help those tumors die, correct spinal cord malformations by stopping the blood flow to the troublesome area, and halt gastrointestinal bleeding.

Over the next 20 years, the applications flourished, and interventional radiologists became increasingly involved in treating cancers, not only preventing blood flow to tumors in places like the liver but also freezing tumors with cryosurgery. They developed procedures to stop bleeding and even to remove kidney stones. Then in the 1980s, industry developed the first microcatheters, tubes so thin and pliable they could be wound into the small cranial vessels, and the field of neuroradiology began to emerge. Madison recalls coming on the scene as a new doctor just as therapies were being invented. “I was involved in the first coiling of an aneurysm in 1994 in Minnesota,” he says. That technique, in which a dangerous outpouch in a brain vessel can be kept from bursting by being filled with compressed strands of platinum, is now a mainstay of aneurysm treatment, often being used instead of open-skull, surgical clipping of the vessel.

Gaining Exposure

Today, there are more than 5,000 interventionalists practicing in the United States. They go through a standard residency in radiology, followed by a fellowship in interventional radiology or neuroradiology. Board certification is granted by the American Board of Radiology. Young physicians entering the field tend to be drawn to its use of imaging and the diversity of hands-on procedures it offers. And program directors have noted increasing interest and enthusiasm, particularly with advances in cancer therapies. At the same time, fellowship slots across the country have gone unfilled. Some instructors fear the vacancies represent students’ hesitation about going into a field in which some of the techniques are performed by other subspecialists such as vascular surgeons. To route students toward the subspecialty, several institutions have made moves to incorporate interventionalist training into the radiology residency program, a combination known as a “direct pathway.”

During fellowship, training addresses not only diagnostic techniques but treatments for an increasingly wide range of health issues. These days, interventionalists may tackle problems that range from unblocking a narrowed or occluded artery or vein using stents in almost any part of the body to destroying kidney or liver tumors, mending thoracic aneurysms, and even treating frostbite and varicose veins. “Any time that you’re working you could do [any of] 30 to 40 different procedures,” says Sanjay Misra, M.D., vascular/interventional imaging fellowship director at Mayo Clinic. “It’s a pretty wide field and has a lot of breadth and depth, which at times, makes it hard to define what we do.”

That diversity of experiences has been invigorating for Andrew Hartigan, M.D., an interventionalist at St. Paul Radiology, whose expertise has him treating myriad conditions, including internal bleeding caused by trauma or a ruptured aneurysm in the chest or abdomen. When treating an abdominal aortic aneurysm, Hartigan might place a stent graft, a mesh tube that’s inserted by way of a catheter, and then expand it to block the bleeding. The procedure is easier on the patient than open-chest surgery (some patients can leave the hospital the next day). And for patients who aren’t good surgical candidates in the first place, the minimally invasive procedure can be a life saver. Recently, he was able to repair a ruptured artery feeding a young woman’s kidney. If she had undergone surgery, he says, getting to the site of the tear would have involved removing her kidney. But by accessing the site through the blood vessels and using occluding devices to stop the bleeding, he was able to spare the organ. “If you can offer a minimally invasive treatment that gets a patient through that emergency,” he says, “that’s huge.”

One of the applications that emerged in the mid-1990s is the use of interventional radiology to treat fibroid tumors. Lately patient interest in this procedure has swelled, according to Jafar Golzarian, M.D., director of the interventional radiology division at the University of Minnesota and a specialist in this technique. In the past, women who weren’t able to get relief from the excessive bleeding caused by the growth of fibroids often ended up having a surgical hysterectomy. Now, interventional radiologists can offer other options. One is catheter-directed embolization, in which interventionalists block off the vessels leading to the fibroids to get the masses to shrink. Not only has the American College of Obstetrics and Gynecology recently embraced this new treatment, but Golzarian is now collaborating with gynecologists at the university to see patients together in a fibroid clinic. Within the first five months, they’ve seen 100 women. “We realized there was an unmet need,” he says. “Patients were going to their gynecologist and getting scheduled for a hysterectomy. And they either wouldn’t go or they would go with reluctance. They were happy to realize that in one visit they could see both experts … about the best option.”

In fact, as the scope of procedures expands, interventional radiologists are interacting more with physicians in all specialties. No longer considered the “specialist’s specialist,” they’re now at the forefront of decision-making in patient care. “We’ve [traditionally] been an underexposed expertise in the medical field,” acknowledges Hartigan. “We’re finally being utilized as a resource, even from referring docs who’ll send us patients in consultation, which is a definite change from 10 years ago. That’s a different level of care [we’re offering] and [a different] vision of us as a specialty.”

Widespread interest in minimally invasive procedures has generated competition from some subspecialists who also perform some of the same techniques, he acknowledges: “There’s a big drive to get into the arena.” And nationally, he adds, many interventionalists are getting edged out of vascular procedures by cardiologists and vascular surgeons. In the northeastern United States, for example, turf battles have erupted because these other specialists—who are largely self-taught in the minimally invasive techniques—have initial access to patients and don’t refer to interventionalists. But at places such as Regions Hospital, Hartigan points out, a collaborative approach between the surgeons and interventionalists has made the working relationship smooth and has ensured interventionalists’ involvement in decision-making and patient procedures. There are several benefits to having an interventionalist perform a minimally invasive technique, Hartigan points out. With their particular training, interventionalists are skilled not only in guiding catheters but also in minimizing a patient’s exposure to radiation. In addition, he says, “there are alternatives we can use that other subspecialists might not offer or have experience with.” For instance, because the standard contrast used in an angiogram can be dangerous for a certain subpopulation of patients with kidney disorders, interventionalists may substitute carbon dioxide for iodine-based contrast, sparing the organ from further damage.

Focusing on Patients

The biggest change in the field recently has been a new focus on caring for patients before and after minimally invasive procedures. Ten years ago, Hartigan says, patients might not even have known the name of the interventional radiologist doing their angiogram. In fact, in a 2001 survey of U.S. patients cited by the Society of Interventional Radiology, only 3 percent were aware of the specialty. That was because a minimally invasive procedure tended to be scheduled by surgeons or other specialists, and even if interventionalists were called in to do the procedures, patients spent virtually no time talking one-on-one with them. Few patients knew to ask for a referral to an interventional radiologist to find out if a minimally invasive procedure was available. Driven by a desire to connect with patients and also to improve outcomes, many interventional radiology practices have begun building clinical space and scheduling time for nonprocedure appointments, where they sit down in the office with a patient, conduct an exam, and talk over the procedure. They also provide follow-up care, sometimes for years after a procedure.

For the last eight years, Misra and his colleagues at Mayo Clinic have been seeing patients before and after procedures and have even written a journal article chronicling the development of their formalized clinic, part of the Gonda Vascular Center. With help from colleagues in vascular medicine, Mayo’s interventionalists began having clinic hours. On a typical clinic day, they might see seven to 14 patients.

What Misra has learned is that “carefully evaluating the patient before, when you’re making the decision to do the procedure, is probably as important [to outcomes] as doing the procedure perfectly.” Factors such as obesity, diabetes, or heart disease can affect treatment. Physicians who make astute observations about which types of patients benefit most from a procedure will be better able to counsel newly referred patients. Incoming fellows, he adds, are learning more about nonprocedural care: “medical evaluation, the use of statin therapy, anti-platelet therapy, hypertensive therapy. You have to keep up with the medicines,” he says, and know when to send patients “back to their primary care provider to make sure they’re adequately managed.”

Hartigan has noted a similar emphasis on clinical care in his practice. “It’s the best thing to do for the patient. They get the best prep, and we’re aware of any potential contraindications to doing a procedure, or potential pitfalls,” he says.

To keep up with the rapid changes in the field, interventionalists read journal articles and attend seminars. Equipment evolves from year to year, allowing for incremental refinements in basic procedures. The technology continues to become more sophisticated, with clearer real-time picture quality. One of the new imaging systems, installed in only a few hospitals nationwide, provides 3D imaging recreated from two-dimensional pictures and can send a probe to a predetermined internal target. Other advances include smaller, less-intrusive cameras and machines that emit lower doses of radiation. In the treatment of cancer, new materials used for embolization—typically small, beadlike particles or glues that sit in the vessels—are emerging. Some new types of beads are loaded with anti-cancer drugs and can both block the blood vessels that feed the tumor and deliver the chemotherapy. In development are radioactive particles capable of targeting only the tumor and new image-guided probes that can be inserted through ports in the skin to deliver radio frequency to tumors or to refine the freezing of tumors. More enterprising uses of interventional radiology include delivering genes for gene therapy.

In the last three years, industry has also introduced new stents for widening vessels or stopping bleeding. Some of the newest ones have branches that can expand in peripheral vessels. Others, designed for use in the delicate cranial vessels, have been refined to spring open gently. With the advances in treatment, there still are some questions. “We don’t have 20-year data on this stuff,” Hartigan says. “It’s accumulating as we speak.” But the immediate results are often quite powerful, as in the case of Madison’s 70-year-old patient who was suffering an acute stroke. After he widened the carotid artery and delivered tPA to the clot, Madison reached for a tool that became available only two years ago: a clot-aspiration catheter, which he used to gently suck the blockage out of the vessel and completely reopen it. Within an hour and a half after the procedure began, the patient, who had been initially paralyzed and noncommunicative, began to move his left arm and leg. And then, “on the table, he began to talk,” Madison recalls. “He left the hospital two to three days later, neurologically intact.

“That’s one of the most rewarding parts of this job,” he adds. “The opportunity to save lives never gets old.” MM

Kate Ledger is a freelance writer in St. Paul and frequent contributor to Minnesota Medicine.