Dr. Marc Gillinov highlights the framework of the Cox Maze IV and how it effectively combats the underlying pathology of Atrial Fibrillation.
For the hearing impaired members of the AFibSurgeons.org community, we have provided a written transcript below:
Dr. Marc Gillinov: The Maze procedure, Cox Maze IV, begins with the left atrium. There are a lot of people who focus only on doing a box lesion, meaning the posterior left atrium, and if you think about the box lesion and say alright, where does that fit, it fits in paroxysmal a-fib more than in non-paroxysmal a-fib. If you think of the box lesion and paroxysmal a-fib and you do a box like this, meaning you get the pulmonary vein separately, maybe you're doing a CABG on someone and you don't want to open the left atrium and you think, I'm just going to take the bipolar clamp, pair it on the right, pair it on the left, maybe four sets of two on each one meaning multiple firings, how good is that going to be for paroxysmal a-fib? The answer is about 60%. We think of the pulmonary veins as being the sites of the triggers for paroxysmal a-fib, and they are the important site of triggers for paroxysmal a-fib, but they're not the whole thing. They're about 60%. If you've got some CABG patient and you say, I'm just going to use a bipolar clamp, guy's got paroxysmal a-fib but I'm just using the clamp, what can I expect? About 60%.
If you were to extend that and do a complete box lesion, meaning it's more than bilateral pulmonary in isolation, then you get the entire back of the left atrium and you get really the whole box. You box out the posterior left atrium and that's going to be worth about 80% of the triggers, which is not bad. This can be done off pump, although it's somewhat demanding to do.
There's no difference electrically between these two lesion sets. For the purposes of treating a-fib, particularly paroxysmal a-fib, these are the same, although we'll get to the point that I think these are the same. I think these are pretty good, but I think we can do better. If I were to have a patient with paroxysmal a-fib and this is what I did, I'd rate it as a B, B-plus operation. I don't get to be a cardiac surgeon, go through medical school, get a great residency, be a practicing cardiac surgeon if the transcript is filled with Bs and B-pluses. You want it to be As and A-pluses. This is not bad. This is maybe the minimum for paroxysmal a-fib, but it's not enough.
When you look at non-paroxysmal a-fib, so now we're talking about anything that's not paroxysmal and lots of different terminologies. Persistent, long-time persistent, permanent, those are the three currently used, non-paroxysmal a-fib means persistent, long-standing persistent, or permanent, basically a-fib that doesn't come and go on its own. The most common mistake, in my opinion, is omitting the right atrial lesions. If you've got a patient who's in a-fib all the time and you decide to skip the right atrial lesions, you're at the B, B-plus range again. The right atrial lesions are important, particularly in non-paroxysmal a-fib. Again, non-paroxysmal, persistent, long-standing persistent, permanent. For our purposes, though, and as a surgeon, you can just say is this a-fib paroxysmal, meaning it comes and goes all by itself, or is it non-paroxysmal a-fib?
If it is non-paroxysmal a-fib, there's a fair bit of data to suggest you should add the right atrial lesions. Here is the key figure or curve from that paper. This is freedom from a-fib in green. The freedom from a-fib is much better if you have right atrial and left atrial lesions than if you have no right atrial lesions, which is in purple.
I think it's not terrible if you omit the right atrial lesions. In fact, it works more often than it fails, but you're operating on someone. The chest is open. It's a once in a lifetime shot to do the whole thing and to do it well. A common argument against the right atrial lesions is won't I cause more pacemakers if I add the right atrial lesions? Don't the right atrial lesions cause pacemakers? The answer is no, not if you do them correctly.
The reason behind the benefit of the bi-atrial lesions in non-paroxysmal a-fib relates to the causes of paroxysmal and non-paroxysmal a-fib. Paroxysmal a-fib is caused by triggers. Basically, when someone pops into a-fib, a-fib's got to start somewhere. There's some anatomic focus where that first trigger, which is a premature atrial contraction, or PAC. It's got to be someplace that starts, and the triggers for paroxysmal a-fib tend to be in the pulmonary veins and posterior left atrium. Once you've got non-paroxysmal a-fib, the triggers aren't doing anything anymore. Once you've got a non-paroxysmal a-fib, triggers are out of the picture. You've got what are called drivers, which are wide areas or volumes of tissue that are sustaining the a-fib. If you're treating paroxysmal a-fib, you're asking the question how do I address the triggers, there is where it starts? If you're treating non-paroxysmal a-fib, you're asking the question where are the drivers, these areas of tissue that are sustaining or driving the a-fib?
If you look at the drivers, which are represented by all these red arrows, and say alright, what if I just do pulmonary vein isolation, which gets a lot of the triggers, 60% of the triggers – what if I just do pulmonary vein isolation in non-paroxysmal a-fib? You interrupt 60% of the triggers – we already knew that – but you do almost nothing for the drivers. The a-fib in non-paroxysmal a-fib is sustained by drivers. Pulmonary vein isolation does next to nothing.
What if you do a box lesion? Non-paroxysmal a-fib, do a box lesion, so you box out a lot of area, a lot of volume. That's better. You interrupt a few of the drivers while getting more of the triggers with your box lesion. Now let's say you extend it. You've got a full left-sided Maze. You've added at the bottom this line on the coronary sinus right in here. You've taken care of the appendage, so the appendage can be electrically active, so you took care of that, got that lined. If you do the full left-sided Maze, you take care of the left atrial drivers, to a large extent. You get a ton of the triggers. In non-paroxysmal a-fib, doing the left atrial or left-sided Maze takes care of the left atrial drivers, but over to your right, we still have the right atrium with its own drivers represented by the red arrows.
If you complete the Maze procedure, meaning basically add these three right atrial lesions, you get about – nothing's 100% but close to 100% of the drivers in normal-sized atrium. The bi-atrium Maze from an electrophysiologic perspective makes much more sense in someone with non-paroxysmal a-fib and the results are better as well. It's a nice story that ties together well. Our understanding of a-fib suggests a bi-atrial Maze is better in non-paroxysmal a-fib and our data on non-ablation proved that a bi-atrial Maze is better for non-paroxysmal a-fib.