Evolution of Mini Maze Procedure for Atrial Fibrillation and Efficacy Compared to Catheter Ablation — Video Interview with Dr. Randall Wolf

Evolution of Mini Maze Procedure for Atrial Fibrillation and Efficacy Compared to Catheter Ablation — Video Interview with Dr. Randall Wolf

By Mellanie True Hills

September 5, 2012

  • Summary:  Dr. Randall Wolf discusses the evolution of the mini maze surgical procedure for atrial fibrillation and the importance of a minimalist approach to lesions.
  • Reading and watching time is approximately 12 minutes

In this video interview, Dr. Randall Wolf, creator of the mini maze surgical procedure, describes the evolution of the procedure and how it came to be called the Wolf mini maze. Dr. Wolf also emphasizes the importance of a minimalist approach to lesions, and the effect that doing more lesions could have on the effectiveness of a procedure. He also discusses how mini maze procedures compare to catheter ablations.

View the video interview with Dr. Wolf (approximately 12 minutes)

About Randall Wolf, MD, FACS, FACC:

Cardiothoracic Surgeon
Indiana Heart Hospital
Indianapolis, IN

For more information, see Dr. Wolf’s profile

Video Transcript:  

Mellanie True Hills:  Dr. Wolf, please share with us about the evolution of the minimally invasive surgical ablation, which patients typically call the Wolf mini maze.

Dr. Wolf:  Thanks, Mellanie. It’s a pleasure to talk with you. You asked me how the Wolf mini maze started — it didn’t start as Wolf or mini maze; it started with an idea. An electrical engineer by the name of Mike Hooven (whom I had been working with) and I were having lunch in the back of my house, and Mike said, “What do you think about using bipolar radiofrequency to treat atrial fibrillation?” I said, “Mike, I’ve been thinking about this. We have to treat the atrial fibrillation in patients who are having open heart surgery. Plus, maybe we can treat the patients who aren’t having open heart surgery with a minimally invasive procedure. It’s a great idea.”

So in 1998, we embarked in the lab on a device that would isolate the pulmonary veins very quickly, with the idea of initially using it for open heart procedures in patients who are having heart surgery anyway and had afib, which was a very undertreated population. At the same time, [we were] developing this device that we could ultimately use for standalone afib – people that only had afib that certainly didn’t want open heart surgery, but wanted some treatment of their afib.

We were wildly successful in the lab. Every time we used this device that we had developed, it worked beautifully in the laboratory. This was at Ohio State University, where I was teaching, and where all the initial work was done. In 2001, we went to Europe, and we did the first open case with the clamp device. Sometime after that, the AtriCure Company was started around that device and technology. The advantage that we had was that we were clamping the tissue, so there was no blood in there, and we could make a very rapid, complete isolation. It only took about ten minutes to make an  isolation. So it was a really big change in the technology.

But all along, my goal was to do this as a standalone procedure. We went from the animal lab to the cadaver lab, and by 2003 (at that time I was teaching at the University of Cincinnati), we were ready to do it as a standalone procedure.

It’s the dry radiofrequency technology that’s the key. We developed a way to get the clamp inside, on the beating heart, without going through the breastbone, as you know, going through the sides. And that was nine years ago, and I’m very happy to say we still see that patient every year. He’s now retired, he’s still doing great. He’d had afib for thirteen years. He was continuous for a year and a half. He’s been off Coumadin and amiodarone for eight years. We’ve studied him at home three times, for a week — no afib. He had bilateral pulmonary vein isolation, really antral isolation, and removal of his left atrial appendage.

From the very beginning, it seemed to be important that we treated the left atrial appendage, for two reasons: One, to decrease the chance of stroke from a clot in the left atrial appendage — if it’s removed, you really dramatically decrease the chance of stroke from afib. And two, in some patients, the source of afib is the appendage. So we really had two reasons.

The original procedure was isolating the pulmonary veins with an antral isolation, removing the appendage, and very quickly on we started also doing testing, the GP testing.

That started serendipitously. I was out in Oklahoma helping Sonny Jackman and his group start the mini maze procedure, and while we were there I toured their labs. Ben Sherlag was in a lab and he was working on the ganglionic plexi, and I said, “What is that?” Ultimately we put Ben on a plane and brought him to the University of Cincinnati, and we did the first-ever case where we also tested the ganglionic plexi. That became an integral part of the procedure as well, because not only are we isolating the pulmonary veins, we’re also treating these little nerves that innervate the veins. And according to Ben, and Sonny Jackman and others, that can play an important role in treating vagal afib.

So I think there are a couple reasons why we’ve had very good success with the procedure. One, we get a complete isolation, a complete ring, beautiful pictures of isolating the inside of the heart as well as the outside. We interrupt these little nerves, which can’t be done any other way. And thirdly, we remove the appendage, which even as we speak today, here in July of 2012, there aren’t other ways to remove the appendage with a catheter technique routinely; I think ultimately that’ll get there, but they aren’t there today.

So it’s evolved a little bit, but what we did find is [that] adding extra lines didn’t help; I did that for a while. I think the reason is that the clamp lines are complete transmural lines — they go all the way through the tissue. When you start doing epicardial [on the outside of the heart] application only of lines — with a pen or some other device — you may not get the same transmurality. You may not get the same complete line, and then you run into the same problems that the EP’s have, which is incomplete lines and skipped lesions. So the key to the technology is that clamp — that is the key.

As you know, there was the first randomized controlled trial in the world comparing catheter ablation to a mini maze type procedure. This was done in Europe, and now it’s over one year out, and the results are in. I think it’s a very important trial, for a couple reasons; in the sub-analysis of that trial, well – first of all, the mini maze patients did better than the catheter ablation patients at one year; the cure rate, if you want to call it that, or afib-free rate, was twice as good for the mini maze, for a minimally invasive procedure, versus the catheter ablation.

But there was also a sub-analysis in there that deals with this business of how many lines should you make, which is very important – many patients ask about that. In Barcelona, they had the classic procedure – bilateral pulmonary vein antral isolation, EP-testing, intraoperative EP-testing, ganglionic plexi ablation, and remove the appendage. So there were clamp lines in a line up to the appendage, which is what I do and is what I taught them in Barcelona. In the other institution, in the Netherlands, they added extra lines, so they had additional lines.

Well in the sub-analysis, the cure rate was better in the Barcelona patients, who had fewer lines, than the Netherlands patients. Why is that? Well, I predicted that, and based on something very simple. The clamp lines are complete lines every time. For the additional lines that are done on the epicardium, or surface of the heart, it’s hard to tell if they’re all the way through, it’s hard to tell if you get a complete line. If we don’t get a complete line, then we’re not doing anything different than the catheter ablation is doing. We open ourselves up to the same sort of problems that they have, with atrial flutter after the procedure, which we rarely see in the classic mini maze type procedure. So this is my impression —  we’ll see how it sorts out over the years — it’s not true, at least in my estimation, that additional lines that are not made with the clamp add anything to the procedure; in fact, they may decrease the cure rate, as it did in the FAST trial.

Mellanie, you asked about the Wolf mini maze, let me tell you the story of how the name came to us, it’s pretty humorous. I operated on a patient a couple of years after we started the procedure. He was a very grateful patient. We have been following our patients every year. He came in for his annual exam, it was around Christmas time, he said, “Dr. Wolf, I have a Christmas present for you. You need to get the word out there. I’ve found you, but a lot of people have not found you. I started a website for you and it’s called the Wolf mini maze.” I said, “Thank you very much, when are we going to put it together?” He said, “Oh no, you don’t understand, it’s already done, it’s up, it’s already on the internet.” 

His name was George Rhea, a very nice man, and he started the Wolf mini maze website, and he also gave me another present at the same time. He said, “Here”, and he had a framed piece of paper, it was a very nice, ornate frame, and it said Wolf mini maze on it, trademarked. He wasn’t an attorney, he went out, and I don’t know how he did it, but he got this trademark that said mini maze on it. He trademarked it and said this is also your Christmas present. So it really all came from a very grateful patient. But we have to give him a lot of credit, because this was early on, and he said you really need to be on the Internet. As you well know, Mellanie, he was right. You have to get the word out there, which is what you’ve been doing. So, credit to that patient for really seeing the big picture.

MTH: Absolutely. So, I understand that you are working around the globe in helping in other countries to do this procedure. How widespread is this procedure currently?

Dr. Wolf: Well, how widespread is the procedure? First, I think it’s important to say that atrial fibrillation is not a disease of the United States, it is not a disease of Caucasians, and it’s not a disease of men. Everywhere that we’ve been, from South America to China to Japan, there’s a high instance of atrial fibrillation, as you know. This is one of those things that is kind of epidemic all over the world.

The first time we had a seminar in China, in Beijing, we put a tiny ad in the paper in the classifieds, two lines; it was an afib seminar that I was going to give, and it was going to be translated into Chinese. There were thirteen hundred people that signed up for it. The venue held 350 people and it was completely full. So this is something that people are aware of all over the world, and a lot of people are not happy with the treatment they have today. They’ve been on the medicines, and they’re not adequate. They realize they’re not cured, so they’re looking for other options. I think that’s one of the reasons why what you’ve done is so important, to get the awareness that there are different treatments for atrial fibrillation. You don’t just have to live with it.

MTH: Right, absolutely. Dr. Wolf, thank you, not only for taking time to share with us about the evolution of the procedure, but also for your pioneering groundbreaking work in helping atrial fibrillation patients get their lives back. Thank you so much.