Cardiothoracic Surgeon Dr. Chris Cook outlines the typical presentation of a patient with hypertrophic obstructive cardiomyopathy and discusses the recommended management of this relatively common disorder.
You're on. All right, we'll get started. Good morning everybody. Um, I'm Chris Cook. I'm gonna talk to you all about uh surgery for hypertrophic cardiomyopathy. Uh This is something we don't see as often as many other things, but uh still an important, an important topic. I have no disclosure. So I will talk about uh hypertrophic cardiom how it presents how we make the diagnosis. And then I'll give a brief overview of some of the medical and interventional therapies. A lot of people in this audience have a great deal more knowledge about these things than I do feel free to ask questions or chime in with your experience or knowledge in in regard to those things. But I will focus more on the surgical treatment of. So, uh hypertrophic cardiom is a genetic disease that has structural and functional abnormalities that lead to some of the typical symptoms that we see with aortic stenosis or other forms of outflow tract obstruction, which are Disney or congestive heart failure, symptoms, chest pain, angina, and then syncopy. It's primarily a disease of the myocyte and it does result in hypertrophy. If you look at this depiction of what the normal heart is versus what we see with left ventricular hypertrophy and hypertrophy can occur for many reasons. Long standing hypertension, aortic stenosis, amyloidosis fabra disease. Some of the infiltrated processes that occur. And we see it in hypertension and aortic stenosis because there is such high afterload, the ventricular muscle has to work very hard for any muscle that's overworked. It does become thicker, that's great for the bicep. It's terrible for the heart. But this is really a disease of the myocyte that has not resulted in that from that pathology. Previously, it's been called a functional aortic stenosis or muscular, sub aortic stenosis, IOP, uh hypertrophic sub aortic stenosis or IHSS and HO which I still do because it's easier to say. But the preferred term is HCM. It was first described pathologically in 1958 by tier. And then uh Bron Wald at NIH uh described the uh characteristic asym asymmetric septal hypertrophy, the myofibril disarray that they saw in pathologic specimens and defined some of the uh dina mic uh sub pressure gradients that occur. It was initially thought to be rare, highly fatal and without really an effective treatment. But today, we know that it's actually significantly more common than we thought it does have a diverse clinical presentation. And overall the mortality for this is low and the adverse event profile is low and that really speaks to the number of patients that are out there, the ones that we see especially from surgery already at somewhat in stage and we do have lots of effective therapies. Um It is the most common inherited cardiac disease prevalence is more than one in 500 it affects people globally and it's equal between males and females. The genetic basis for this was first identified in 1989 when the first gene was discovered uh to contribute to this. There's uh now uh over 1400 mutations seen in at least eight genes um maybe up to nine now. And it does have an auto uh dominant transmission. So these are some, some of the uh familiar um sketches from uh medical school. But you can see that within the cardiac myocyte, the myo filaments interact with one another. These two slide together to shorten the sarcomere and then these heads of myo along the min rod, then act as a ratcheting mechanism to slide this filament against the other. As you can imagine, this is a highly complex structure, multiple proteins with interactions. And so there can be multiple areas for some genetic mutation. And as it has been defined, there are many of these proteins which can have mutations, my binding protein C being one of the more common at 40% and beta ma and heavy chain at 40%. And then you can see some of these others that are less common Troon and it and C all with just a single digits and percent. But there's multiple areas by which you can have an abnormality that can result in ho if you look at pathologic specimens. This is a normal myocyte. You see these nice parallel sarcomere with their nuclei and parallel capillary blood flow running through the muscle here. This is chaos fibros are running in all different directions. And then you see that this dense connective tissue that's starting to fill in here, non cellular scar tissue that is forming. That's all the intramyocardial fibrosis. And you can actually see some small vessel thrombosis. So this may be a very benign disease in many people. And it can be such for many years. However, some people can have sudden death, heart failure, symptoms due to obstruction, which can be treated with drugs, septal, myectomy, alcohol ablation and or advanced heart failure. Sometimes we see these people at end stage and we really can't do anything for them. And the answer for those folks is heart transplant. And occasionally we see people who are decompensating due to atrial fibrillation present with stroke. And then the mainstay of treatment is that it would be for any other atrial fibrillation patient with rate control, hopefully, rhythm conversion, anticoagulate anticoagulants, ablation if needed. If you look at the natural history of ho overall, the average survival of it is not bad because of the wide clinical presentation. There are many of these people who are not in uh long term or severe in stage heart failure and they're managed well with medications. But there is a drop off in survival over this 10 year period because there certainly is a subset of those patients that are in trouble and living with heart failure. In general. The life expectancy is really close to normal. When you look at all of these patients, death can be sudden and unexpected occurs usually in young adults who were previously asymptomatic and usually it follows a period of vigorous exercise. This is the 21 year old undiagnosed basketball player who drops dead on the basketball court. And, uh, primarily that can be due to ventricular arrhythmias. One of my former partners at the University of Pittsburgh. Um, his wife was diagnosed, we had a discussion about what we should do for her. Uh, she needed to get on medical therapy right away. She was symptomatic. And, um, so I, at that time was very young in my career, did not have very much experience with. There wasn't anyone doing it, uh, with great frequency at Pittsburgh. And I said, well, I think she needs to, to go to Mayo clinic right away. And, and he said, yeah, I think we're gonna, maybe we're gonna do that soon. And a week later on Mother's Day morning, they were having breakfast and she dropped dead at the kitchen table and he couldn't revive her. And, uh, so it does happen and she was only symptomatic for a few weeks prior to this. So, these patients present with diastolic heart failure, the the the heart will eject all the blood that you give it as with any other form of hypertrophy. The heart just simply can't relax and accept a volume. They have increased uh wall stiffness due to hypertrophy but also due to the fibrosis that occurs, uh then they get left atrial pressure that increases and then subsequent dissa they can actually get uh myocardial ischemia due to the increased wall stress and the increased two demand and decrease in capillary network. And as I told you before, they may actually get some fibrosis of the small capillary networks. Um They get these abnormal small arteries that are thick and eventually uh the aluminum becomes obliterated. Uh two thirds of patients who have, have some form of obstruction with varying degrees. Usually it's due to the thickened septum. Uh they may have micro regurgitation due to septal uh uh um uh elision from the systolic anterior motion of the anti leaflet. Um It's variable in its presentation and it can be dynamic. Patients could be symptomatic at one point and not very symptomatic at others depending on their hydration status and their level of activity. It may limit their cardiac output and then further increase the ischemia and it becomes this vicious cycle where their fibrosis progresses and certainly they get heart failure symptoms. Uh The mitral regurgitation that occurs is usually due to the systolic an interior motion on the micro valve and I'll show you what that looks like. Uh the jet is generally East Center um and usually it's in mid to late Sicily, as the ventricle starts to empty, empty, it will empty effectively early in the systolic cycle. But as the ventricle continues to collapse, then the anterior leaflet swings over and obstructs the LVUT. There may be some structural abnormalities uh to the micro as well or at least the sub or app but that is less common. So, if you look at how these patients present with obstruction, it can be ischemic. As I told you, uh decreased cardiac output, mitral regurgitation and these things leading to increased left atrial pressure. The ischemia may present with chest pain with the increased left atrial pressure. They may get pulmonary congestion, diastolic dysfunction contributes to that. And this ischemia uh becomes a feedback loop uh due to the myocardial fibrosis and ultimately decreased cardiac output or they may present with a arrhythmias which can either be atrial fibrillation or B or B FIB A fib, then presenting with decreased cardiac output or stroke and BB fib with either sudden cardiac death or syncopy. So this depicts what is going on during sly, you can see that there is ejection that occurs early through the micro valve and then the anterior leaflet swings over against this hypertrophied septum and essentially blocks the LVT. But also pushes. We used to think that this was called a venturi effect where the anti leal, the microvalve then gets sucked over towards the septum. But it's actually a psion mechanism whereby blood then shoves the anterior leaflet over against the septum and results in a lack of coaptation of the two mitr leaflets and then mitral regurgitation. And this is just another picture of that. So early on there's ejection, but then later on in Sicily, you can see that that's when they obstruct and then that's when they get the mitr leak. And this just sort of to indicate to you that the mit regurgitation really occurs in the mid to late sly. So two thirds will have some structural abnormality, the microvalve and usually that's not the leaflets, it's a subvalvular apparatus, the leaflets can be elongated, the pai muscles can be anteriorly displaced, but a lot of times there's abnormal cordate or there's accessory pappy muscles that insert directly onto the leaflet without really having much of a cord. As you know, atrial fibrillation contributes about 15% to the overall cardiac output. And when you have someone who has a ventricle that will not relax, and now you lose the ability to completely fill the ventricle. They will have a decline in cardiac output immediately after going into atrial fibrillation. Not only that the rate goes much faster when you're in atrial fibrillation. Such that any time there's an increase in heart rate, obviously, the cardiac cycle is decreased, but what suffers the most is the time in diastole and that's really what these patients need is more diastolic filling time. So as heart rate goes up and the entire cardiac cycle is shortened, the time in diastole is shortened, more so affected than the time in cysto. So they may decompensate rather quickly and they can actually pass out or even provoke sudden death. Some of these patients will have autonomic dysfunction. This is a bad sign. They'll have an abnormal blood pressure response to exercise. Systemic basal dilation that occurs during exercise. As you might imagine as is true with aortic stenosis. When you dilate systemically, your afterload reduces, that only serves to increase the gradient. So if their afterload is is decreased, it just gets worse and that's an abnormal response to low blood pressure and this occurs despite the appropriate rise in cardiac output that is seen with tachycardia and it's certainly associated with a poor prognosis. This is an unfortunate pathologic specimen or hopefully it was someone that was transplanted. But you can see a few things in this. Obviously, there's the large diffuse hypertrophy that has occurred here. But if you look at the sub endocardial zone here, it has suffered a significant amount of ischemia as evidenced by the lighter color due to the scar tissue. And you can actually see here, scar tissue grossly, not under a pathologic specimen. You can actually see scar tissue and this this part here is actually irreversible. So, not much can be done about that unfortunately, this person also suffered an a infarct. There's multiple patterns of hypertrophy. Uh This goes from um if you look over the history of ho they really did not recognize this as a sort of a single entity with multiple presentations, but it can just affect asymmetrically the septum or it can be the entire septum. It can be isolated more to the lateral free wall, which is somewhat rare. These people can also have this called mid ventricular cav obstruction, which neither affects the base or the apex or it's diffuse concentric hypertrophy or the apiol form, typical exam findings for these. These people really not much on their vital sign. They may be a little bit Tayar when you first see them and that's how they're maintaining cardiac output initially because their stroke volume index is decreased. Their heart rate actually goes up, which is detrimental in the long term and a compensatory mechanism that doesn't work well for very long, they may have a normal blood pressure, normal respiratory rate unless they're in heart failure and normal saturations. Their neck exam may be normal except for their carotid up stroke. So they will not have Juul or venous distinction, but they may have a bio carrot up stroke that is brisk and then a systolic murmur which is characteristic of any type of L VT obstruction. Their murmur disappears with squatting and that is because of the reason that I mentioned before, increased afterload then decreases the gradient and you might not hear the murmur at that point. They typically don't have signs of right sided heart failure. So you won't see anything on abdominal exam and they really rarely have peripheral edema and good pulses distillate. So the work up uh CBC and chemistries are normal. Their B MP may be elevated. EKG will show left ventricular hypertrophy. Their chest x-ray is generally normal in advanced stages. They have may have mild pulmonary congestion, but there will usually not be despite the fact that the heart is thicker, that you would generally not see cardiom. A halter may show absolutely no arrhythmia. And that is the most common finding is that they don't have arrhythmias. Te is really the mainstay of diagnosis and you will see left ventricular hypertrophy and that may be in the basal septum, which is most common. And certainly these patients have diastolic dysfunction. As we pointed out. If you look at the EKG, you will see that there's a very large tall Urs consistent with left ventricular hypertrophy. You may see Q waves in any, any lead and these nonspecific T wave abnormalities. And in the APY variant, those T wave inversions and elevations may be diffuse. Um echo will show the ef will be normal or even super normal. And you can also identify the variants that I showed you the basal septal hypertrophy, mid cavity apiol or even diffuse. The aortic valve is generally normal. Uh the mit valve tends to be structure really normal most of the time. But you may see a moderate to severe mitral regurgitation uh with the post yearly directed jet that I that I showed you and they have am they will typically have a left at enlargement due to left at pressure that is increased and the right sided uh structures, the ventricle and tricuspid valve or generally normal. This is a classic uh parasternal long axis view of a transthoracic echocardiogram showing uh a normal widely opened aortic valve. You see this very thick septum, the right ventricle looks normal. And then you see the anterior leaflet of the my now almost completely obstructing the left outlo track on catheterization. You may see bridging on their coronary anatomy due to the significant hypertrophy that is now choking the coronaries on their hemodynamics. You may see this characteristic Brock and bro bald morrow sign or just usually called Brock and bro sign, whereby after you have a P BC, you have a less effective ejection immediately thereafter. But then you have a period of prolonged diastolic filling and that very next beat is going to be much stronger, have a lot more cardiac output because they had some more diastolic filling time. MRI is something that we do when the echo is inconclusive or we're actually doing surgical planning and it provides some additional an atomic information. You can see this MRI shows a normal right ventricle and you can see here, a very large diffusely thick, thick and left ventricle. And you can see what's most impressive about this study is that even down at the apex, but also up at the base, the injection fraction is 80 to 90%. The other things you can see are some of the sequela of long standing untreated um hypertrophy. And that is that there is the a scarring that we see on uh MRI like was on the pathologic specimen that I showed you. So, a flow tract obstruction may be absent in 20%. Um Most people will have it um uh or um some type of obstruction and you can diagnose it about half the time uh in a resting state. However, there will be people that have and they are symptomatic and you get studies that don't really show that they're obstructing. Um And these are the people that undergo some form of provocative testing and what we'll call la, you have to induce them. So, one of the things you could do is give them IOL as you know that the chronotropic and inotropic effects of is are going to exacerbate this because it's going to increase the heart rate and it's going to increase the contractivity, all the things that you don't want in. But it may be helpful in making the diagnosis by provoking uh an increase in the LVOT gradient. Interestingly for the people that you find that are symptomatic when they talk to you, you don't find anything on non invasive testing and then you do some type of provocative test. It is a very good predictor of how they're going to do with surgical treatment. So if you find those things and you say, well, we can only find this disease on provocative testing, well, then they're actually going to do quite well with surgery treatment. We want to obviously relieve their symptoms and prevent sudden death. Medical therapy is what most people get because most of these people are never going to come to all the other procedures. Some of the historical things that we have done micro valve replacement in a small subset of patients. This was done very early on in the treatment for hoco septal ablation chamber pacing has been tried with not much success and then septal myectomy and of course an advanced end stage transplant. So this is a busy slide. But if you look at the hoco population, there's some of those that are high risk for sudden death. And I'll tell you more about who those people are. They may get icds for primary prevention or secondary prevention. If they go into atrial fibrillation, obviously aggressively treat atrial fibrillation, they may have progressive heart failure symptoms and at that point, they need to be treated with drugs. Typically starting drug is beta blockers, then verrall diaper and other medications now that we have available, um, if they really don't have STYS and generally, we don't start them on treatment. If you've identified somebody or at least a familial pattern, then you might want to send those people for genetic testing. Let's say you've got them on drugs and they've got obstructive hokum at rest or provocation and they have refractory symptoms. Despite medical therapy, then you might want to consider them for surgical myectomy for those patients who will tolerate an operation and then other alternatives to surgery, meaning alcohol septation or pacing. But as I mentioned, pacing is not really something that uh proved to work very well. This is an old slide from 2003 and we've since discovered that that's not as helpful. So for uh non obstructive in stage disease, you know, all the standard medical therapy with after load reduction diuretics, uh beta blockers and then ultimately on the heart transplant. So all these medications uh decrease the LV two gradient, decrease the oxygen demand and increase diastolic fiddling. And if those things fail, we can move on to intervention. Um So the drugs really target everything that effort causes. So when you go for a brisk walk, run up downstairs, something like that, your heart rate goes up. Uh there's decreased filling time. As I mentioned to you before, there's decreased uh more so in diastolic filling. So they have less preload, there's increased contractility and decreased afterload, all of those things that you don't want. And so we use these medications that I mentioned beta blockers calcium channel Diapy and val as well. But Mavica is a drug that has come on the scene more recently. So beta blockers obviously affect inotropy and chronotropic and give them more filling time. And it's really pretty effective at reducing symptoms. And about half the people, calcium channel blockers historically have primarily been with vera and act by the same mechanism. It may be effective in those patients who have not done as well with beta blockers. But it may actually cause clinical deterioration because of the baso dilation with the fall and afterload. Then their gradient worsens and they actually become more symptomatic Diapy. Mad is a very old class. One anti rhythmic. It's also a very strong negative inotrope that reduces the outflow tract obstruction and it's effective in some patients who failed the other two classes of drugs. Um activation of transforming growth factor. Uh beta is involved in the development of my cardio hypertrophy and fibrosis, modifying disease progression by inhibiting that with valsartan may improve cardiac structure and function. And certainly it's been shown to be slightly better than compared to placebo Mavi Campton, who was the first in class cardiac my site inhibitor phase three randomized trial called Explorer HCM, was a double blind placebo controlled trial and it showed that their exercise capacity was improved. There was a decrease in the LVOT obstruction, their heart function, functional class improved and their overall health status and symptomatic scores were improved. Um Many patients will develop atrial fibrillation. Who have, you have to treat it aggressively. If you're planning surgery, you really need to consider doing a maze procedure on these patients. One of the presenting symptoms are ways that people present and have unknown ho and then they go into atrial fibrillation and they present in full blown heart failure. So, some of the non surgical interventions I'll run over alcohol septal ablation pacing and I CD. So A S A was first introduced in 1995. And so what you do is cannulate the L AD, find a large septal perforator. So obviously, they have to undergo coronary a geography. Um When you have this asym asymmetric septal hypertrophy, um what you do then is find that large septal perforator do a balloon inclusion and then inject alcohol after beyond this to induce a septal infarct tier. Um So this study showed that there was uh survival and functional improvement was better um or comparable when compared to surgery. However, they had more pacemakers after alcohol septal, many of the patients with ho will present with some degree of left bundle branch block, alcohol septal preferentially will block the right bundle. So now you've put them in complete heart block when you do that and they may have more ventricular arrhythmias. After ablation, you are inducing an infarct after all, uh reintervention rates are much higher uh for alcohol, alcohol septal ble, but it's still only about 10%. But with surgical myectomy reintervention is uh very low. Um This was somewhat of an ominous finding in this paper and, and uh when it's this striking, uh you have to call it into question. But this comparison between septal myectomy and alcohol ablation follow up over 10 years really showed a remarked difference in survival in these two groups. Um And this study, you know, this was done by a very good friend of mine who's now at Mayo. Um He's a, he's a, a writing machine. He probably has 20 publications under review at any one time. And he did this meta analysis was um results were somewhat different than those seen historically. So I think he published this in 2019. Um and he looked at 22 alcohol septal ablation, cohorts and 23 septal myectomy cohorts and tried to compare those um as best he could and he found that uh myectomy was associated with a higher uh procedural mortality and stroke 2% versus uh 1.2% which did have a statistically significant p value. Um Alcohol septation was more need for pacemakers 10 versus 5% which was also this was strongly significant um during follow up all calls mortality, cardiovascular mortality and sudden cardiac death rates were somewhat similar. So he concluded that repeat septal reduction interventions were more common uh after uh alcohol septal ablation and that pacemaker need was greater. Another good friend of mine, Dr Tarea shared this slide with me last night out of his kindness. But if you look at this and you look at the right bundle and the left bundle, you see when you do an alcohol septal ablation, you induce preferentially a right bundle in FARC as opposed to a surgical myectomy that more often affects the left bundle. Many of these people already have some degree of left bundle branch block. So you don't really care too much if you take that out. However, if they've got a left bundle branch block, and now you give them a right bundle branch block, you've now given them a need for a pacemaker, dual chamber pacemaking. This was a prospective study but really small numbers here, they showed no significant difference in symptoms, their ability to exercise or their vo two max. And so pacing really was not recommended as a primary treatment for uh implantable defibrillators can be used for secondary or primary prevention in high risk patients. I first saw this slide. I thought of an aortic stenosis patient I had who was an elderly gentleman at a crosswalk and the light, the the walk sign turned and he had a cane and he was moving slowly. So he was trying his best to hurry but got in the middle of the street and face planted from syncopy due to aortic stenosis. Uh So every time I see that I think of him sudden death in is is variable. Um life expectancy is Neoral, as I told you, for most patients, there are clearly some families with a malignant history and early sudden death and those people should be considered for primary prevention and planning an I CD before something bad happens. If you look at the risk stratification for those high risk patients, if they are having symptoms and they're much younger, they have spontaneous or non non sustained syncopy, they actually have a drop in their blood pressure with exercise, some type of perfusion defect on a thallium or any other perfusion study. They see a significant myocardial bridge or they've actually had an arrest and the malignant family history, as I mentioned, first degree relatives. And if they have a really massive left ventricular hypertrophy, meaning defined as more than 30 mil milliliters. Uh Unfortunately, they may end up with that kind of an EKG tracing. Uh in stage cardiac failure is a small percentage of uh of these patients. And uh heart transplantation is uh really an option. Um Now, uh from my perspective on to the main event, uh surgery. So early on uh mechanical micro valve replacement was done for hoco, what this does is nothing for the septum, but it may reduce the degree of mit regurgitation. And you may see some mass regression in the left ventricle after this, but it really just helped the degree of mit regurgitation, but it also took the leaflet, the anterior leaflet out of the way. Um So they may have significant symptom symptomatic improvement. So it gets rid of the MR. But by eliminating the anterior leaflet, it will open up the LVOT somewhat. It may be useful in patients who you tried to do uh something to, to their septum and they failed or reoperative patients and particularly those patients with a thinner septum. So we generally operate, operate on these people. If they have severe symptoms, they've had a poor response to medical therapy. Their LVT gradient is greater than 50. They do have anatomy that is favorable, diffuse patients don't do well. Patients who have a focal um subaortic membrane or hypertrophy do really well. Um they have some other need for surgery. So, concomitant pathology. Uh So if we look at all of these patients who have hoco, only 5% are surgical candidates. Early surgery should be done for those people who have severe pulmonary hypertension. They have significant left atrial enlargement with atrial fibrillation. They are not doing well from symptoms and have a poor functional capacity and younger patients who have high gradients really should be referred for surgery. This is Dr Morrow who in 1961 described the first surgical intervention for this. You can see on this ventricular gram. Here there is a basal collapse with still retained contrasts in the LV and a complete obstruction almost of the LVOT and what he did. And it's a little bit hard to see in this. But if you look, he actually went through the aortic valve and used this uh finger myo to this instrument was used first for mit stenosis. So, before microvalve replacement, before cardio pulmonary bypass, patients who were diagnosed with mitral stenosis would get a left thor eot a purse string around the left atrial appendage and then put a finger through the mit valve and then essentially tear the mitral valve open for rheumatic disease. That same instrument he used to go by this approach. And then you can see in this smaller side here where he's actually fractured a significant amount of the septum. The first one he just did with his finger and then he had two more than he did using this. Uh then it was his famous paper and one of the um uh one of the classic papers of cardiac surgery, which was called the morrow operation. He didn't publish until 14 years later and this was on 83 patients uh with a uh 7% mortality. These patients had significant symptoms and were identified to have asymmetric uh septal hypertrophy. 52 patients were studied postoperatively with repeat catheterization. 47 had no gradient and five had a gradient that was less than 25. So this was really hailed as a quite a surgical success. And in this operation, he used a trans aortic valve approach to go in and remove a one centimeter uh block of tissue in the LVOT. And it actually worked really well. So initially, he just removed this sugar cube of tissue here, but then started extending that deeper into the ventricle. And you can see this is really what you were left with was this rectangular resection here. This is the right coronary ostium here. And you can see that in this area here at the um meum is the site of the A V node. So if you stay directly below the of the right coronary sinus, if you stayed leftward of that, you should avoid this. And that's one of the tenets of surgery. So if you look at this pattern of obstruction, you can see that this is not only in the um immediate area beneath the aortic valve that really involves the entire septum. You can, if it is mostly isolated to the septum, do sort of the classic operation, but that can actually be extended down into the ventricle, avoid the conduction system and take this all the way down to the pap muscles. Some people describe getting near the apex at least until you get to the base of the papilla muscles. This is the standard approach. This is the approach that we use for aortic valve replacement or repair. So this is the hockey stick um incision aortotomy that is performed above the sin of tubular junction. You then put traction sutures above the commissures to expose the valve. That's kind of my standard exposure for aortic valve surgery. And then you see here, this balding septum in the LVT. And they've sort of depicted here, this whitish area showing that uh that there's a scar there. Um The classic operation, you made a one centimeter deep incision and then a parallel incision to that, this first incision starts. Uh If you look at the hinge point here of the um of the valve, the aortic valve that start about 8 to 10 millimeters lower than that. Generally, we can get it up even closer than that. But that's where that incision starts. And then you make the parallel incision here, connect the two and then push the knife towards the apex of the heart and expose it even further. One of the things I wanted to point out is that this is a sponge stick that's depressing on the right ventricle that then allows you to see that a little bit better. You don't want to push too hard because it gives you too good of exposure and you might get a VSD which I'll talk a little bit about. There's not much harm in extending this more leftward on beneath the left cause many of these patients will have sort of this diffused pattern. And you can generally pretty safely extend this all the way over towards the anterior leaflet of the mit valve. So, uh you can see in this slide here that here's the bulging septum. This is the right coronary cusp, which is carefully being uh track um you can see before the myectomy. Uh there is this um bulging septum here, but this extends also over towards the microvalve. And you can see that some of that tissue has also been resected here. This is just another slide showing the same thing. This bulging asymmetric septum that's been resected. And this is generally what we take out. You can see here the myocardium, but this endocardium is very abnormal. This is heavy dense scar tissue here from turbulent flow, but also the subendocardial fibrosis. So this is much thicker than the normal endocardium. We can measure the pressures. This is a catheter that is connected to a needle that goes into the right ventricle through the septum and into the left ventricle. And then you can actually measure another pressure at the same time in the ayin aorta. I have just hooked this up to the cardio plegia line um and just measured it that way directly, which also works and you don't have to put another needle in there. It's another way of doing it. So if you look at these gradients, when you measure them interoperate, this is what you'll see on your tracing, prem myectomy. And then afterwards, you should test them again to look at the functional um uh result of what you've done in the operating room. So if you were to get in the operating room and you were to find that it wasn't too impressive at rest under anesthesia and then you give them isoproterenol, you are likely to be able to provoke that gradient and have a objective measurable data. Uh the provocable gradient. Afterwards, after post myectomy, you can see you don't have the same response that you do after you administer the isopro. Again, what about this a variant? You can see that directly under the valve. There, there is some hypertrophy but this is mostly affecting the apex. And unfortunately, this is another pathologic specimen. If you look at what happens to these patients, they have a decreased stroke volume with time and they have this increase in their in diastolic pressure. This is just a classic pressure volume flow loop that you see. And so the operation to do that is to go through the apex and then resect all of this muscle and obviously spare as much as you can of the valve. So here's what that looks like you go on cardio pulmonary bypass, you sub lux the apex make an incision in the apex. The led is over here. This is directly into the um a segment. You can see how thick all this muscle tissue is and uh get retraction on this and expose really all of this cavity. And then you can actually start making a circumferential Corine of this uh of this tissue where you go around and then you take this up to the pai muscles and then that's what you're left with. Um And then you close this up as you would for ventricular aneurysm. You can see that this is a ventricul gram that is done pre and post a resection. This is a difficult operation. It's somewhat daunting. I've actually never done this operation. Sometimes cutting into a non infarcted ventricle. You might think. Well, this is, this is, you know, a bit daunting in the aspect that you're not cutting through dead tissue. However, you're giving them such an improvement in their stroke volume by taking out all that tissue that any damage that you're doing to the apex is really pales in comparison to the advantage that you give them. And then here's what you see postoperatively. Um This is a measure of the stroke volume overall, as you know, and you can see that they have a significant improvement in their stroke volume and they no longer have this elevated resting in diastolic pressure, that little notch is gone. So the key points about this, these ventricles are very thick. These operations generally don't take a long time, but you do have to pay close attention to myocardial protection because it is hard to protect a very thick ventricle. You need to avoid the conduct conduction tissue, try to protect the aortic valve, obviously going in to do a operation and then having to come out with that. Plus now inducing some amount of restriction that you see that is inherent to any prosthetic that we pull off the shelf to replace the aortic valve with. You haven't gained as much advantage they showed in those and using Ross retractors to expose the valve. I like those um little malleable ribbons. I think that they're gentle and it helps you get a very good focal exposure. This is something that we don't have, you know, a good setup for retractors like we do for the Metro. So really it has to be someone, an assistant helping you and holding that. So they have to be very careful. And so those malleable small malleable ribbons, I think work very well. You have to make sure that you do an adequate resection. And if you come off bypass and you find that you still have a significant gradient and both by appearance and but really by measuring the gradients, you still, you still have a problem. You really need to reclamp rearrest, go back in and take out more tissue and then obviously address any microvalve pathology. Most of these patients will have some degree of Sam, you'll come in with severe mitral regurgitation and you think I'm going to have to do something. But if you do inadequate resection, you're probably not going to have to do something to the MIT valve and you should tolerate mild and maybe even up to moderate mit regurgitation for this operation. Because with time and medical therapy and with LV, mass regression that's going to occur, they may get somewhat better. So management after Myectomy this would be the same as you would for anyone with AM or uh significant LVH. You want to reduce that gradient by making sure that they have increased after load and that the ventricle is very full and it's not contracting on itself. So you want to increase their preload, you don't want inotropes on board, you want to keep them volume loaded. So you're going to avoid diuretics and these people avoid vasodilators and then beta blockade is tolerated. Surgical results, improved symptoms and exercise decrease in syncopy, you can get rid of the LVT gradient altogether. You can eliminate Mr and you can actually restore normal L pressures. The operative mortality for this operation is less than 1%. There's a decreased incidence of sudden death, a low incidence of recurrence for surgery. As I showed you, there was only 1% need for reintervention after septal myectomy. And these patients actually have long term survival. As you can imagine, once you relieve the outflow tract obstruction, a similar phenomenon happens with the rest of the ventricle that has become hypertrophy due to the long standing obstruction, which also happens that we see commonly with aortic valve replacement in people with long standing aortic stenosis is that the rest of the ventricle with time gets better and they have LV mass regression and the rest of the ventricle that has become hypertrophic. So if you look at them over time, this is actually a pretty striking result now, they do have some recurrences and, but this tends to plateau with time, but in the early periods, you will see that there's a significant decrease. Now, obviously, you've resected a little bit of the LV mass, but it's not on the order of 150 g. So obviously, there's something that goes on with the ventricle. After this, the upper mortality I said is about 1% permanent pacemaker rate is less than 2%. You can get A VSD. If you do get A VSD, it needs to be patched with pericardium right away, autologous or bovine or something finding A VSD later. And then trying to do intervention with the plug does not work. You need to take them back to the operating room and patch the septum aortic valve. If you damage it or if they were to happen to have concomitant, some aortic valve pat pathology or you might leave the person with significant residual mitral regurgitation. So this looked at the long term effects of myectomy and it showed that you uh you almost restore them to a normal survival curve at 10 years after this operation. If you look at myectomy versus those patients who don't get a myectomy, but they have non obstructive cardiom, some of these patients still die of sudden death and then those patients that are obstructive that don't get operations, they die off at a much quicker, much quicker rate. This was published by some of my former colleagues and they looked at intervention with regards to the MIT valve. If you look at the mortality, those who went myectomy only versus those who went repair replacement. There was a barely statistical significance in those patients and their mortality who underwent survival. Then if you divide them in repair versus replacement, it was a little bit better for repair. So also other things with VSD, there was if you create a VSD, they're going to have worse survival, obviously, because it's now a longer operation. It's more complicated. The long and short of this slide is they do a little bit worse if you have to intervene on the micro valve. If you intervene on the microvalve, it's better if your repairs replaced just like anything else that we've seen. So, um this is, this was one of my cases. This was a 65 year old lady who presented with, with uh operated on her um year and a half, two years ago, something like that. And this was her echo finding. You can see that her septum is 1.7 centimeters. Here's sort of the classic finding. You can see that the anti leaf of the mit valve is coming over against the septum and completely obstructing the LVT. If you look at this, you can see that not only do you have all of this turbulent flow as indicated by this mosaic pattern beyond the aortic valve up into the sinus segments. But you see that there is this jet. And when you look at this play, you can see that, you know, there's really almost complete obstruction of everything for a little while. And this is a still image of that showing turbulent flow in the LVT. And then you can see this turbulent post yearly directed mit regurgitation jet. This was after Myectomy. So you can see now here's the anti leaf of the microvalve. You don't see the L BT well, in this view, but I took this image because you can see that this is the myectomy. The papyri muscles are going to be starting down in this region. And you can see that this is now widely open, insistently, the septal leaflet is completely away from the anti leaflet is completely away from the septum. And there's good coaptation. This was this was a picture when I first saw it. I was both proud and terrified because I looked at it and I thought, wow, that looks like a great myectomy. But then you get the sense. 00 no, here's a VSD. I worry terribly about this patient. I listen to her heart every day for a harsh murmur because you know, you take out all this tissue, but you're also probably going to surgically remove a septal perforator. You know, she get in with residual amount of tissue is there or this muscle just start to open up. So I was really worried about her, I got to follow up on her a month ago and in the clinic and it looked just the same. Um And you can see this is the dynamic shots of that. This was the area that's moved. This was a little more reassuring that the septum was not as thin here. But you can see that the micro regurgitation is still there, but this is mild and I chose to leave that on a follow up echo. It was no more than trace. If you look at the therapeutic effy e efficacy of these things. Um um you know, percent residual gradient of greater than 30 millimeters. You can see that it's a very low percentage for septal myectomy excellent results, septal ablation not as good. Um maca not quite as good disopyramide and beta blockers. If you look at these, how they step down myectomy really shows itself to be the um the best treatment for this. So, in conclusion, um hypertrophic cardiom is a common inherited disease. It's much more common than we once thought. It has a diffuse phenotypic expression and therefore a, you know, a diffuse wide ranging clinical presentation in natural history. Um It may progress along one or more disease pathways. They can present in atrial fibrillation with a stroke, they can be in heart failure, they can pass out. Uh There's multiple things available, we kind of touched on uh all of those things and focused more on uh surgery. Um but uh you know, this is uh you know what I do for a living so I can make the last statement that it's the most appropriate and effective therapy. So, interestingly, the most common cardiac disease that cats suffer from is hypertrophic cardiomyopathy. This is my buddy Buster and he's got some problems with increased respirations and he's got a murmur but I haven't echoed him because it's expensive and he's really old, but uh he may have, but at this point, we're we're managing without disopyramide or pacing. So, yeah, I don't know if there were any questions. There were a couple of comments, comment, question. Oh, that's 100 and 28 people on uh John Kudos and David. Uh um So Dr Adler mentioned that MitraClip is an effective treatment for many patients with Mr. How would you select patients for surgery versus alcohol? What factors would you consider? So, um I think a younger patient with a high gradient who's obviously going to tolerate the operation. Um Certainly if they already have, you know, a left bundle and now you're going to induce a right bundle by doing an alcohol ablation, you're going to put that person into complete heart block. So those are the things you know, can they tolerate, can you do they have favorable anatomy, meaning that it's confined to the septum. It's not a diffuse type. Obviously, if it's somebody that has a, I would probably, you know, refer to that patient that's not an operation that's done very often. It's only done by a handful of people in the country and worldwide. So those that are younger with a high gradient who have a good operative risk, uh, who already have, um, a right bundle would be all the patients that I would more likely, uh, go to, um, surgery. All right. Thank you so much. Thank you.
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