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Angioplasty.Org Interview Series: Transradial Approach
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Interview with Jennifer Tremmel, MD

Jennifer Tremmel, MD is Director of Transradial Interventions at Stanford Medical Center and Clinical Director of Women's Heart Health at Stanford Clinic. Dr. Tremmel studies sex differences in cardiovascular disease. She is an Interventional Cardiologist who also trained in Preventive Cardiology. In her clinic she cares for women who are at high risk for coronary artery disease, women who have symptoms concerning for heart disease, and women who already have heart disease. She has a particular interest in women who present with symptoms of heart disease, but are found to have "normal" coronary arteries on angiography. Her current research investigates whether women presenting like this are more likely than men to have coronary abnormalities that cannot be detected by angiography alone, such as endothelial dysfunction, diffuse deposition of plaque, or microvascular disease.

Dr. Tremmel received a B.S. in Psychology and an M.D. from the University of Iowa. She did her Internal Medicine Internship and Residency at Dartmouth-Hitchcock Medical Center, followed by a Master's Degree in Epidemiology at the Harvard School of Public Health. She completed her Fellowship in Cardiovascular Medicine and Interventional Cardiology at Stanford University Medical Center, where she was also a Postdoctoral Research Scholar at the Stanford Prevention Research Center.

For more about the transradial approach, visit our Radial Access Center.



Jennifer Tremmel, MD
Jennifer Tremmel, MD, Director of Transradial Interventions, Stanford Medical Center and Clinical Director of Women's Heart Health at Stanford Clinic

Q: Why did you decide to start using the transradial technique for angioplasty?
Dr. Tremmel: Well I had an epiphany. It had bothered me that my patients were periodically having bleeding or vascular complications. It certainly wasn’t happening at a higher rate than anyone else’s but whenever it happens it's an unfortunate situation: the patients don't like it and it certainly can lead to a lot of morbidity and mortality. Being someone who does research in sex differences, I knew that my women patients were more prone to having bleeding complications. I could say to them, "Well, you're more prone to having this problem," and they always looked at me like, "So what are you going to do about it?" and I couldn't really give them a good answer. The answer certainly was not vascular closure devices because those don’t decrease bleeding complication rates. You try to improve your technique as much as you can but you still have these complications.

This was always in the back of my mind and one day I saw an article which said that both sexes have significantly lower bleeding rates with transradial intervention, particularly women, because they have higher bleeding rates at baseline. So when I saw that, I was like, "This is it!" It seemed like the answer to taking care of these vascular complications. I felt a real obligation to figure out a way to lower bleeding complications just because I'm a women's heart health specialist and that's my job: how do I improve the outcomes of the women that I take care of? In my mind, transradial was the answer.

Q: Why do women physiologically have more bleeding complications?
Dr. Tremmel: No one knows exactly. I think it's multifactorial. Some thoughts are that women’s vessels are smaller, so when people are trying to get access, they may use more needle sticks, or they may be more likely to experience posterior wall sticks, where the needle goes through the vessel. There also are some thoughts that women wind up being overdosed with medications because their size is smaller. But even if you dose them properly, women still have higher bleeding rates than men. There also are some thoughts that their vessels simply may be more fragile. We know they're more prone to getting things like dissection and that sort of thing, so there may be something about the hormonal milieu that makes their vessels more fragile and prone to bleeding. Nobody knows exactly why. If we knew exactly why, it might help us decrease the gap.

Q: You mentioned that vascular closure devices don't really decrease the bleeding complications.
Dr. Tremmel: Vascular closure devices decrease the amount of time that somebody has to lie flat after a procedure. They can get up sooner. There's a lot of patient convenience. But anybody that sells you vascular closure devices will be honest with you that they don't decrease vascular complication rates. We know that from quite a bit of literature.

Q: Patients write into The Forum on Angioplasty.Org about the problems and concerns surrounding their groin puncture and its healing – less so about the stent in their coronary artery.
Dr. Tremmel: Right. That's what people remember about their procedure: the time afterward when somebody was pressing on their groin for four hours, or they were lying flat and their back was killing them. They take away a lot about how their whole procedure went based on how the post-procedure part went. You could have done the most beautiful complicated angioplasty in the world, but they don’t care if they have this giant bruise down their leg, or they're getting transfused.

St. Vincent's Transradial Training
St. Vincent's Transradial Training
Course in NYC

Q: Once you made the decision to do radial interventions, how did you go about learning it?
Dr. Tremmel: It was one of those things where, if the student is ready, the teacher will appear. It was in my mind, “OK, now I need to learn how to do radials,” and it was just kind of luck -- for some reason the Terumo rep came through our lab and said "I have some training available -- would you be interested?” And I said, "Yes!”

So I took the next plane to New York -- I did the St. Vincent's transradial course in New York that Terumo hosts. It was a day-and-a-half and I left feeling very comfortable and confident that I could go back to my institution and start doing them. And I did.

I chose a specific nurse and a tech so I would have the same people with me as we were starting to learn and I wouldn't have to go through it with everyone and people wouldn’t be all upset -- because anytime you try to do something new, people are like, “Oh my God, what are you doing?” So they scrubbed in on all my cases and we figured out how we were going to set up the patient and what equipment we needed. The nurses in the cath lab got used to what we were doing and what it looked like afterward. I also had one nurse in the holding room who was specifically assigned to my patients.

I used the TR Band and learned what it was about and we did that for a month or so. There was certainly a lot of buzz around the lab like, “What are they doing?”

    TR Band™ Radial Compression Device
TR Band™ Radial Compression Device (courtesy Terumo Interventional)

So at that point I held an in-service for the whole lab. And I asked my nurse and tech to start teaching everybody else to do their parts. And everyone got pretty comfortable with it. Then we trained the floor nurses, so that when patients come out, they go to the holding room and then go to the floor, and the nurses knew what to do with the wrist bands. It turns out that it's much easier to deal with. The nurses actually love it because they don’t have to hold any groins. And the patients are very autonomous. They can get up, and go to the bathroom and they don't need bed pans and all of that.

Q: So you did the in-service only a month or two after you returned from New York? It was really see one, do one, teach one.
Dr. Tremmel: Yeah. I was really motivated to do this. It rung so true to me that I really wanted to make it work. They had told me at St. Vincent's that it's best if you try to do it 100% of the time, as opposed to trying to pick and choose. That made sense to me and so I came back with a plan that I'm going to do this 100% of the time. When I started doing it, some would work and some wouldn't and I didn’t always know why it wouldn't. I would say it's spasm but I didn't know if it was spasm. So if it didn’t work we always had the groin prepped.

Stanford Medical Center
Stanford University Medical Center

We're a teaching institution so I also did radials with my interventional Fellows -- once I felt comfortable, I let them start learning. I did my training in June and by mid-December, when I looked back, I realized that they had become exceptional at doing this.

And from mid-December until this week (April 2009) we didn’t have to go to the groin once! So we’ve had almost a four month period of success.

The learning curve's fairly long which everyone always says. It took us about six months to become really really good at it, but then we got really really good at it! We just kept at it. In the beginning it was frustrating sometimes and it was tiring.

Interventionalists like to get things done and when we're really good at something it's nice to just go in and do it and in five minutes you're done! So it's hard to step back and say okay, I'm going to do something new and I'm going to go through this. But in the end, it really paid off. And it didn't take that long. It's all now a past memory.

Q: The rest of the world uses the radial approach 40-50% or more, and the U.S. is way behind, in the low single digits -- you even had trouble finding training. What are the major roadblocks to the adoption of the radial technique? Is it motivational or is the problem that there's just not enough training out there?
Dr. Tremmel: I think it's a lot of things. The initial thing is that learning to do interventions is really an apprenticeship. So you learn from your mentors and they teach you what they know. That's how I was trained.

Secondly, I would say that, for the most part, it works great through the groin. When we have bleeding complications, we do fine with most of them. Rare cases can be lethal, however, as you know, so retroperitoneal bleeds can be lethal, particularly if people who are not paying attention. But with bleeding complications we’ve kind of said, "Well, this is part of angioplasty..." and we've accepted it, when in fact maybe we don’t need to accept it -- and certainly not at the rate that we have it. It's kind of like stent thrombosis -- we went through the part where stent thrombosis was terrible and now we're getting used to it. It doesn't happen very often but, when it does, it can be awful. Certainly, if more people were bleeding every single day, then they would be looking for other options.

I think third, you have to learn something new, and if you're out of the learning phase or far out from Fellowship, you just may not want to be learning something new. You may feel pretty good about what you're doing.

Fourth, I think is training. You're right. At this point it's still a little bit harder to find training. You've got to get time off to go do it. So you would have to be motivated to do the training.

And then I would say fifth is that the patients at this point still don't know about radial that much. Or they don’t know there are options, so there's not feedback from the patients, such as, “I would actually prefer that you do it through the wrist. Oh you don’t do it through the wrist? Well maybe I'll go somewhere else.” So I think that's an issue. Once people find out that you do it that way and maybe they've seen an article or something, once they hear that there's another way to have this done and that their bleeding risk may be lower and that they can get up and walk right afterwards, they may come asking for it. And I can tell you that's going to motivate a lot of interventionalists to change because their patients want that.

Then there's actually another reason: the equipment we use. I think the equipment is getting a lot better. I know people tried starting radials in the past and ran into a lot of frustration because wires and sheaths were harder to get through. Certainly the stuff that we have available now, hydrophilic wires and hydrophilic sheaths that slide through and these radial-specific catheters that can do the right coronary and the left coronary with one catheter, I think that, as the equipment improves, cardiologists will be more motivated too, because it will be simpler, they'll have less obstacles in mastering the technique. I think there's some remembrance from the older practitioners that it didn’t go very well, that it was hard to get stuff in and that sort of thing.

Q: In the not-so-distant past, catheters and sheaths had to be larger French sizes because the balloon profiles were bigger.
Dr. Tremmel: Right! Everything is smaller now. And there is certainly misinformation. Yesterday I did a lady who is 37 kilos. That's the smallest lady I’ve ever done. She's 81 lbs. And I did it through her radial artery. She had a beautiful return when we got in. I was shocked. Her wrist was so tiny, but we had no problems with it. And that was part of the doing 100% and not picking and choosing -- because you really don’t know. You automatically would say that all the big guys are going to be easier -- which is in general the case, but this teeny little woman, no problem. And she was certainly at high risk for retroperitoneal bleed from the groin, because we know that the majority of people that bleed are women. The studies that I did with my colleagues showed that 73% of the retroperitoneal bleeds were women. And also small body surface area. So, little women, high risk for a retroperitoneal bleed.

Q: What has been the impact on your practice and with your colleagues, now you're doing all these cases radially?
Dr. Tremmel: The impact? Certainly we don't have any bleeding complications. It was funny, the Fellows yesterday were like "You never have any complications" and I said "I know. Isn't it nice?" So that's an impact. There are more people who are requesting to be done this way: patients and referrals. The big thing is having referrals: people specifically send their patients to you because they would like it done this way. Periodically I get called up to the lab, "Can you come help do this radially because we're having groin problems?” So it's a service that I've been able to provide that we didn’t have before. And my colleagues have said that we should disseminate this and we should all be learning it. That's really what I was hoping for -- that they also would want to start doing radial.

Q: You’ve recently given presentations to some managed care groups – are there economic implications with the radial approach?
Dr. Tremmel: I've talked to them about cost-effectiveness. Overall radial comes out to be less expensive than femoral. Particularly if you're using closure devices with your femorals -- it's a lot cheaper to do it radially. Particularly if you add in things like nursing afterward and hospital stays -- all those things become shortened. And fewer complications are always less expensive. We're in an era now of healthcare reform and these are the issues that are really going to come to the forefront and I think hospitals are going to be looking to find ways of having people do interventions radially, if they can, because it will lower their costs and complications and stays.

Q: Do you think meeting organizers from ACC to SCAI to TCT should be putting more emphasis on training cardiologists in radial during those meetings, like with live cases, etc.?
Dr. Tremmel: Those would be great forums for training courses because you can be trained quite quickly, at least enough to have confidence to go back and try it. We're all interventionalists, so we know the basic technique of getting into an artery and advancing sheaths and advancing catheters. You just need some sense of how to do it in this particular way. And then you have to go back to your institution. A lot of it is trial and error, knowing when you need to stop, and when you can keep going. And your confidence grows as you do more of them. And you don’t need days and weeks of watching somebody or having them watch you. When I did Dr. Coppola's training course, I think I got to do a stick three times, and that was really helpful, having somebody right there with me. But I certainly think that ACC and others could give some information be it videos or simulators or watching live cases that would enhance people's learning. People walk away from these meetings with the sense that “this must be important because it came up a lot and it got a lot of press”, so they're thinking, “I'd better learn about this." That's why we all go to these meetings.

Q: Any final words of advice to cardiologists who don't now practice the radial technique?
Dr. Tremmel: Try it, you'll like it!


This interview was conducted in April 2009 by Burt Cohen of Angioplasty.Org.