An Interview With Mark W. Mewissen, MD
A renowned vascular radiologist shares his wisdom about the state of the practice, SFA stenting, and online education.
You were part of the team that performed the first endovascular treatment of AAAs in Wisconsin. What impact has this technology had on vascular practices in the Midwest?
In 1998, I presented some early work on "over-the-wire" arterial thrombolysis at CIRSE, at which John Abele introduced himself to me. It was the start of the Mewissen catheter, a device that became a popular thrombolysis catheter, particularly when used coaxially with a Katzen wire to lyse acutely thrombosed vessels. I like to believe that it is my good relationship with Boston Scientific that allowed the Medical College of Wisconsin to be part of the very competitive Vanguard aneurysm trial, the first of its kind in the US to objectively evaluate an endograft for the repair of an aortic aneurysm. Involvement in the trial gave me the opportunity to meet and interact with Barry Katzen, MD, and Hugh Beebe, MD, who were national principal investigators, and who crystallized the "ideal" endovascular team, consisting of an interventional radiologist and a vascular surgeon. I believe that it is the introduction of aneurysm devices that, for the most part, has triggered the current interest we see in the vascular surgical community for angioplasty and other catheter-directed procedures. Some teams survived the politics and have probably strengthened their presence in their respective local markets. Others have failed, and as a result, they have seen their vascular work quickly swept away from them. Radiologists who continue to be actively involved with endovascular programs have succeeded by being clinically active, and as a result have become better competitors in their environment.
In 1999, you left an academic radiology practice and joined a private cardiology group, and you are now the Director of the Vascular Center at St. Luke's Medical Center. What are the major differences between these two types of practices?
At the Medical College of Wisconsin, the vascular and interventional radiology section was not set up to operate and claim any market share in the rapidly changing field of vascular medicine. There was no clinical infrastructure in place to see patients and make independent decisions about treatment strategies and follow-up care. We were basically providing a very limited technical service to patients under the control of vascular surgery and other clinical services. We had no referral base and were not equipped to compete. The radiology leadership did not perceive this eminent threat to the section and was reluctant at the time to inject the necessary resources for change.
Wisconsin Heart and Vascular Clinics, a large private group of cardiologists in Milwaukee, was very attractive to join because they had the vision to integrate a vascular medicine service within their cardiology practice. In fact, Michael Jaff, DO, a renowned vascular medicine specialist, started his career with the group. Jim Gosset, MD, and Gerry Auger, MD, have now taken the lead and have been my partners since the beginning. The group gave me an opportunity to become a vascular interventional consultant in the hospital, integrate midlevel providers in my practice, and provide pre- and postintervention care in a clinic setting. After 8 years of practice build-up, I have become an active player within a market in which competing interventionists (primarily cardiologists) routinely perform complex vascular interventions. Referring physicians have a choice, and I believe it to be a good thing in a competitive model.
In the past 5 to 10 years, many interventional radiologists have been able to change and adapt within their own practices. There are many creative models out there, but active clinical involvement is imperative for success. Today, claiming the right to a procedure because of training and skills alone is not good enough. We must set ourselves up to be viewed as consultants by referring physicians and be in a position to refer our patients back to other specialists, such as a cardiologist for cardiac clearance before an aortic aneurysm repair or a wound care specialist after a tibial angioplasty. That is how the network is built. We cannot just expect to take and never give back. My advice for any radiologist contemplating joining a new practice, be it surgery or cardiology? Hard work, passion, and patience. It will take time to build the practice, but the benefits will slowly become apparent. In a competitive market, it is not always how much you know that will determine success; rather it is how fast you are adapting to change. I believe we must run our interventional practices in ways similar to running a business delivering a product.
You were among the first to publish the outcomes of SFA stenting with a self-expanding nitinol stent, with results that were better than anticipated. Were you convinced that nitinol stenting would work so well, and were you surprised at the outcomes?
The anticipation that nitinol self-expanding stents would not do well in the femoropopliteal (FP) segment was based on suboptimal results reported with use of the Wallstent. In fact, The TransAtlantic Inter-Society Consensus (TASC) document, published in 2000, clearly stated that FP stenting as a primary approach to treating chronic limb ischemia (CLI) was not indicated. Very early on, I started deploying Smart stents in end-stage wpatients with CLI and very limited surgical options. Technically, I was able to pass the delivery catheter without predilatation in most cases, and I had full control of the trailing end of the stent. This was a very important feature in patients with proximal FP disease, as I was able to avoid crossing the profunda femoralis artery.
Early in my fellowship training at the Medical College of Wisconsin, I was exposed to the academic thoroughness of Dennis Bandik, MD, a vascular surgeon who taught me the value of objective hemodynamic follow-up of vascular interventions. In my new environment at St Luke's Medical Center, I was fully equipped to follow up with all my patients in the clinic and in the vascular laboratory to define the natural history of a deployed Smart stent in the FP segment, objectively observed at regular intervals with color duplex scanning. Whatever the results, I knew that others would eventually report comparable data using similar endpoints and standard follow-up imaging techniques. I first presented my early experience on 88 limbs in 77 patients at ISET 2002. The technical success rate was 98%, acute thrombosis was rare, and the 6-month duplex patency rate was 82%. This may have come as a surprise to many but not to a few interventionists like Gary Ansel, MD, and John Laird, MD, who were sharing similar findings with me. I later published patency rates of 92%, 76%, 66%, and 60% at 6, 12, 18, and 24 months, respectively, in 137 patients with a mean lesion length of 12.2 cm. Not to my surprise, similar patency data were later reported in BLASTER and in the bare-stent arm of SIROCCO. More recently, in the New England Journal of Medicine, a randomized trial comparing PTA versus primary stenting demonstrated statistically significant superiority in the nitinol stent arm, with patency data very similar to my own published experience. I am convinced that selected patients with CLI and nonhealing ulcers are ideal candidates who are most likely to benefit from FP stenting. This strategy is undoubtedly superior to balloon angioplasty alone.
I anxiously await new data to be presented on the various nitinol stents currently in trials. We know that all nitinol stents are not equal with respect to patency and stent fracture. As clinical experience with each new device grows, the spectrum of lesions for which it is appropriate will become better defined.
Are you currently involved in any clinical trials?
One of the most exciting trials that I am involved in is VIBRANT, which is designed to compare the PTFE-covered Viabahn stent with nitinol bare stents in a randomized manner in patients with intermittent claudication and/or resting pain who have at least 8-cm-long FP lesions. I am honored to share the principal investigatorship with Gary Ansel, MD (cardiologist), and Patrick Geharity, MD (vascular surgeon). This multidisciplinary commitment to the trial, sponsored by Gore & Associates, will add credibility to the results of the trial. This approach reinforces my belief that the modern vascular interventionist may emerge from various training backgrounds. I am also privileged to work with interventional cardiologists committed to carotid stenting since the very beginning. Tanjir Bajwa, MD, although a local competitor, has included me as co-investigator on all the carotid trials to date. In the spirit of collaboration, we have learned tremendously from each other, and it is better for patient care in general. I am responsible for certain research efforts, and he takes the lead on others. This approach has worked well because it allows us to enroll patients faster in some trials.
What can you tell us about your new online resource for physicians, Vascular Video?
I founded Vascular Video Inc. to provide online endovascular resources for health care and industry professionals. The idea is to capture all the video information seen on the x-ray monitor during any intervention. The digitized file can thereafter be edited to create what I call an "Endovascular Video Intervention," or case study, that offers clear and concise audiovisual information simulating a truly "live" case without the inevitable down time of a broadcasted presentation. I believe this unique format has the capability to deliver educational programs to showcase procedures, products, and methods pertaining to the growing field of endovascular intervention.
Vascular Video Inc. can be viewed at vascularvideo.com. It is ambitious on my part and probably utterly optimistic, but working with incredibly talented young people has been worth every second of the project.