Systolic Anterior Motion After Mitral Valve Repair
In our Mitral Foundation Video Teaching Library we are going to show a series of cases that demonstrate teaching points in the field of mitral valve reconstruction. In today's video, we're going to talk about systolic anterior motion after mitral valve repair. These are our disclosures. The systolic anterior motion occurs after mitral valve repair due to an excess of leaflet tissue versus the anterior lateral height of the orifice of the mitral valve. The posterior leaflet pushes the anterior leaflet into the outflow tract. There are two principal causes for this.
One is excess height of the posterior leaflet after reconstruction. The second one is a ring size that is too small for the available leaflet tissue. In either circumstance, the posterior leaflet will coapt at the midpoint of the anterior leaflet, and the tip of the anterior leaflet is pushed into the outflow tract. The case we're gonna present is a 56 year old male, and a 20 year history of asymptomatic mitral valve prolapse, who presented with new onset endocarditis after some dental work. His transthoracic echo, which I'll show you, demonstrated posterior leaflet prolapse with preserved ventricular function. And following antibiotic treatment he was scheduled for surgery. The echocardiogram demonstrates an anteriorly directed jet with a mass and prolapse in the posterior leaflet.
It's not clear whether this is vegetation or just myxomatous change from chronic prolapse. You can also see the annulus is dilated. A common message that endocarditis occurs in valves that are abnormal, not normal. So this patient's obviously had long-standing mitral valve regurgitation. Here's our examination of the valve in the operating room. You can see a ruptured cord and a tall prolapsing P2 segment.
The adjacent segments appear to be normal height. We would classify this as fibroelastic deficiency. And in this patient, there's several different techniques you could use, and we're gonna use a triangular resection. You can see it's not a very wide base.
We're just excising the prolapsing free margin, and a little bit of the excess tissue in the body of the leaflet. We're going to close that with interrupted sutures, in this case we also use running suture from time to time. Note we've put all of our annuloplasty ring sutures in as a first step to really improve our exposure prior to resection. Now we're true sizing a ring.
We're matching the intercommissural distance as well as the surface height. And in this case, we're implanting a true size 32 physio ring. The closure line is posteriorly displaced. That's a demonstration of the ink test with the ventricle full of saline. And you can see we have about a centimeter of anterior leaflet below the mark of ink. Here's the echo after we come off bypass. We had systolic anterior motion. You see the mobility of the tall posterior leaflet pushing the anterior leaflet into the outflow tract.
And after optimization, the patient had a residual gradient of 40 millimeters across the outflow tract. This is the sort of patient where you need to make a decision whether to go back on bypass or not. This is an algorithm that we published in the Journal of Thoracic and Cardiovascular Surgery last year, explaining our strategy.
The first is to avoid inotropes, raise the mean pressure, optimize preload and avoid tachycardia. And often times we'll give Esmolol to slow the heart rate down. If the patient has persistent SAM, then you have to make a decision whether you wanna try and ride this out medically or operate. Certainly in younger patients or asymptomatic patients we would always elect to Occasionally, you'll have a patient where you're right on the border, particularly older patients where you may wanna go upstairs and follow this over a few days. Most of the time, we'll re-explore the patient, and when we do, we'll do something to lower the height of the leaflet. In this patient, we chose to re-explore him.
You can see we're marking the closure line again, and the first step is to optimize our exposure by putting one of these retraction sutures in the ring. Now the first thing I'm gonna do is I'm gonna close the margin of every indentation and cleft. And what I'm trying to do is create a curtain effect. I want to decrease the mobility of the posterior leaflet, so by closing these clefts, we're gonna start to pull the leaflet below the coaptation line, and that's going to improve the motion of the anterior leaflets. So the first step is we're going to close all the indentations and clefts.
And the second step we chose in this patient was posterior leaflet displacement. You can see by closing the clefts, the ink on the anterior leaflet is starting to rise up, and that shows you that you've lowered the leaflet. Now to continue to displace the posterior leaflet, we're going to use a simple Gore-Tex cord, we pass it through the tip of the papillary muscle, and through the free edge of P2. And now we can tie this below the ring plane, down into the ventricle. And by effectively displacing that now you can see an even lower closure line near the edge of the ring. And there's the post-op echo now with a wide open outflow tract and normal motion, and resolution of the gradient.
There were several teaching points on this video that deserve emphasis. First of all, systolic anterior motion is going to happen to all surgeons that perform mitral valve repair. We try and minimize that risk by lowering the height of the posterior leaflet.
And by respecting carefully the size of the orifice of the mitral valve when you choose your prosthesis, versus the available leaflet height. When you get systolic motion, the first step is to optimize the preload conditions, lower the heart rate, and raise the mean pressure while you stop inotropes. If patients continue to have persistent systolic anterior motion, most of them should be re-explored in the operating room.
When you reexamine the valve, of course you want to consider your ring size. Most of the time you've made the correct ring size choice. If you're in doubt you went below, down a size instead of up a size, if you're in between, you may consider changing the ring. But that's not our usual, our first step. Our first step usually is to lower the height of the posterior leaflet. Whether we do that with the resection technique by excising the base of the leaflet, or in this case, where we closed indentations and cleft to create a curtain effect and then used a Gore-Tex cord for displacement.
Once you've done that, you usually will resolve the systolic motion, and of course, you want to confirm that on echocardiography. If you're left with a little residual gradient in the operating room, then we simply opt to continue this optimization of the patient afterwards. Then we check an echo a few days after surgery, and almost always, you'll see it resolve.
I hope you found this video instructive. And please send us your comments and questions.
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