Hypertrophic Cardiomyopathy – Cardiomyopathy

by Joseph Alpert, MD

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    00:00 All right, so here’s a diagram. Again, the same one you saw for the dilated cardiomyopathy. On the left-hand side, you see the normal ventricular structure - normal left ventricle, normal right ventricle. Now, look over to the right and you see a typical abnormality and diagram of a hypertrophic myopathy. The septum is much thicker than normal and the free wall is much thicker than normal. And you’ll notice that the cavity size is markedly reduced.

    00:29 Now, there are a number of things that can occur in the patient with hypertrophic myopathy.

    00:40 Sometimes, the bulging septum, you can see it here in this diagram, actually gets in the way of the left ventricular outflow tract and actually impairs blood leaving the heart just as if there were aortic stenosis. In fact, this, when it was first described, was called subaortic stenosis that is stenosis that’s below the aortic valve. That’s one form of so called septal hypertrophic cardiomyopathy. But, as I’ve said before, you can have a hypertrophy in other parts of the left ventricle and on occasion, even the right ventricle is involved. The thickened heart muscle has impaired relaxation, so the diastolic filling pressures of the ventricle are increased and this often results in increase in lung pressures that can lead to edema in the lung and increased pulmonary pressures and then even some difficulty for the right ventricle. And as I said, the form with the big, thickened septum can often be obstructive to the outflow tract of the left ventricle and can actually function like aortic stenosis below the aortic valve.

    01:53 The symptoms are variable. Most patients have no symptoms and they may be discovered routinely because they have an abnormal electrocardiogram. Somebody gets an echo and says, “Oh, you know, you have a hypertrophic myopathy.” We then go through the family and find a number of family members. The vast majority are asymptomatic, lead normal lives, need no therapy other than being regularly watched by their doctor. I follow a number of people in my clinic, including one of the former higher officers of the University of Arizona, who’s now in his 60s and he was found out by accident to have hypertrophic cardiomyopathy when a cardiogram was abnormal.

    02:32 He hikes vigorously. He’s had absolutely no problems despite his hypertrophic cardiomyopathy and I’ve seen people in their 90s with it who are also asymptomatic. The individuals who are symptomatic often complain of shortness of breath with exertion. They may actually even develop angina or the most worrisome symptom is fainting - syncope with exertion.

    02:56 That’s the patient that’s high risk for sudden death. Again, in this case, the syncope is, as my professor had said, aborted sudden death.

    03:06 There are a number of signs when you examine the patient. Very often, they have a systolic murmur that sounds a little bit like aortic stenosis, but it gets louder when the patient stands up or when the patient does a Valsalva maneuver, that’s the same maneuver where you grunt like this as you’re moving your bowels. Each of those shrinks the left ventricular cavity a bit and causes obstruction to the outflow tract and the murmur gets louder.

    03:30 So you have the patient stand, the murmur gets louder; you have the patient lie down and the murmur gets softer because the ventricle gets a little more blood and dilates up a little bit. There may be a very muscular apex beat that you feel on the chest wall and there may be evidence of arrhythmias - abnormalities in the regularity of the heartbeat.

    03:58 The treatment is usually Beta Blockers in fairly high doses. This decreases some of the hypercontractile component of this disease. But also, a calcium channel blocker - verapamil, an antiarrhythmic drug - amiodarone and others are often used. When the patients are thought to be at high risk, they will often have an implantable defibrillator - a pacemaker that can detect an abnormal, malignant heart rhythm and shock the heart. Or they may undergo surgical therapy in which a portion of the thickened septum is removed, often with considerable improvement. None of the drugs or surgery have been shown to prevent sudden death. And so, in patients who are high-risk for sudden death, for example, the people I mentioned before who faint, we put in a defibrillator. And I’ll show you a slide of the defibrillator, the implantable defibrillator, that’s put into patients we think are high-risk for sudden death or who’ve been resuscitated from sudden death. There is one therapy where alcohol is injected down a branch of one of the coronary arteries, killing some of the heart muscle.

    05:05 This has been suggested as an alternative to surgery. It’s, of course, a lot easier than opening the patient’s chest, but turns out it’s less effective and is not used very often at all. And I’m going to show you some diagrams of this. This slide just, again, points out the surgical interventions and the possibility of implanting a defibrillator in patients who have malignant arrhythmias. And of course, we also pay attention to things like minerals in the blood, potassium and so forth. Even when patients have been operated on, they often end up still requiring drugs when they’re symptomatic. Most of the asymptomatic patients with hypertrophic cardiomyopathy require no therapy other than monitoring them to make sure that they’re not getting worse in any way.

    05:57 Here’s just a little diagram to show you the alcohol septal ablation. You see on the left part of the diagram shows you the thickened left ventricle, shows you the left anterior descending coronary artery. A catheter is placed down in a branch, and you can see on the right-hand side some injection of alcohol and that heart muscle dies. It’s, by the way, quite painful when we inject the alcohol. So, the patients need to have significant drugs on board, morphine and so forth, to dull the pain. But, this technique is not done as much anymore. What is really preferred is mostly to open the heart and to remove a piece of the septum surgically. That has had the best results. Again, this is not an operation done by all heart surgeons. Since it’s not done that often, most of these operations are done in specialized centers and certain heart surgeons become very expert at doing it. So, if you need that operation, of course you want to go to somebody who’s doing this all the time, not somebody who just does one on occasion.

    About the Lecture

    The lecture Hypertrophic Cardiomyopathy – Cardiomyopathy by Joseph Alpert, MD is from the course Cardiac Diseases.

    Included Quiz Questions

    1. Interventricular septum
    2. Lateral wall of the left ventricle
    3. Ventricular apex
    4. Outflow tract of the right ventricle
    5. Atria
    1. Larger size of the left ventricular chamber
    2. Obstruction to blood flow from the heart
    3. Impaired relaxation
    4. Rapid, forceful contraction of left ventricle
    5. Increased pulmonary pressure
    1. Standing
    2. Squatting
    3. Lying supine
    4. Lying in the left lateral position
    5. Hand-grip
    1. Metoprolol
    2. Digoxin
    3. Furosemide
    4. Lisinopril
    5. Amlodipine

    Author of lecture Hypertrophic Cardiomyopathy – Cardiomyopathy

     Joseph Alpert, MD

    Joseph Alpert, MD

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