Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is very common condition that is often the cause of sudden death in young people, including young atheletes. Despite this it can affect people of all ages and affects both men and women equally.

Hypertrophic cardiomyopathy occurs when the heart muscle (myocardium) becomes abnormally thick (hypertrophied), thus making it harder for the heart to pump blood properly.

Because Hypertrophic cardiomyopathy has very few or no symptoms it often goes unnoticed and undiagnosed until it is too late. In some cases of HCM, the thickened heart muscle can cause shortness of breath, chest pain or problems in the heart’s electrical system, resulting in the occurrence of arrhythmias (life-threatening abnormal heart rhythms).

What causes it?

People with hypertrophic cardiomyopathy have a genetic mutation that causes the heart muscle to grow unusually thick, plus myofiber disarray, an abnormal arrangement of heart muscle cells. This disarray can contribute to arrhythmia in some people.
Most people with hypertrophic cardiomyopathy have a form of the disease known as obstructive hypertrophic cardiomyopathy, in which the wall (septum) between the two bottom chambers of the heart (ventricles) becomes enlarged which causes an impediment of blood flow out of the heart. The severity of this disease can vary widely among patients.
Hypertrophic cardiomyopathy does not always occur with significant blocking of blood flow, however, the heart’s main pumping chamber (left ventricle) can become stiff, reducing the amount of blood the ventricle can hold and the amount pumped out to the body with each heartbeat. This is referred to as nonobstructive hypertrophic cardiomyopathy.

What are the risk factors?

Hypertrophic cardiomyopathy is usually an inherited disorder with the odds of a child inheriting hypertrophic cardiomyopathy from the parent with the same condition being about 50%. Because of this, any close relatives of a person with hypertrophic cardiomyopathy should be tested for the disease.

What complications may arise from this condition?

Although many people with HCM don’t experience any significant health problems there can be some complications, such as:

  • Arrhythmias: A fast or irregular heartbeat can be the result of a thickened heart muscle, as well as an abnormal structure of heart cells can interrupt the heart’s electrical system. Among these are ventricular tachycardia and ventricular fibrillation. Atrial fibrillation can also increase your risk of developing blood clots, which can travel to your brain and lead to a stroke.
  • Obstructed blood flow: In many people, obstruction to blood flow can cause shortness of breath with exertion, chest pain, dizziness and fainting spells due to their thickened heart muscle.
  • Dilated cardiomyopathy: In a very small percentage of people with HCM Over time, thickened heart muscle may become weak and ineffective over time. The ventricle becomes enlarged (dilated), and its pumping ability becomes less powerful.
  • Mitral valve problems: Because the thickened heart muscle can leave a smaller space for blood to flow, blood can be forced to rush through your heart valves more quickly and forcefully, preventing your mitral valve from closing properly. The mitral valve is located between your heart’s left atrium and left ventricle. As a result, blood can leak back into the left atrium (mitral valve regurgitation), potentially leading to a worsening of symptoms.
  • Heart failure: Heart failure can occur as a result of your heart muscle becoming too stiff, making it hard for your heart to pump enough blood to meet your body’s requirements.
  • Sudden cardiac death:Ventricular tachycardia and ventricular fibrillation can cause sudden death. Although rare, people with hypertrophic cardiomyopathy have a heightened risk of a sudden cardiac death – approximately 1 percent of HCM patients. Hypertrophic cardiomyopathy can cause heart-related sudden death in people of all ages, however occurs mostly in people under the age of 30.

 

WHAT ARE THE SYMPTOMS EXPERIENCED?

The first symptom of hypertrophic cardiomyopathy among many young patients is sudden collapse resulting in a possible death. This can be caused by the blockage of blood from the heart to the rest of the body or by very abnormal heart rhythms (arrhythmias).

Some patients however have no symptoms and may not even realize they have the condition until it is found during a routine medical check up.

Some common symptoms are:

  • Light-headedness (Especially with or after activity or exercise)
  • Fainting, especially during exercise
  • Dizziness
  • Fatigue
  • Chest pain
  • Shortness of breath with activity or after lying down (or being asleep for a while)
  • Sensation of feeling the heart beat (palpitations)

 

HOW IS THIS CONDITION TREATED?

The goal of treatment is to prevent sudden cardiac death in people at high risk whilst relieving their symptoms. Specific treatment varies depending on the severity of your symptoms.

Possible treatment options include:

Medication

To ensure that your heart can pump more efficiently, you may be given medications to slow down and relax the heart muscle. Calcium channel blockers such as verapamil (Verelan, Calan, Covera-HS) or diltiazem (Cardizem, Tiazac, Dilacor XR), beta-blockers such as metoprolol (Lopressor, Toprol), propranolol (Inderal, Innopran XL) or atenolol (Tenormin), or medications to control your heart rhythm such as amiodarone (Cordarone, Pacerone) or disopyramide (Norpace) may be recommended.
If you have atrial fibrillation, in order to reduce the risk of clot development, your doctor may prescribe blood thinners such as warfarin (Coumadin, Jantoven), dabigatran (Pradaxa), rivaroxaban (Xarelto) or apixaban (Eliquis).

Septal myectomy

This is an open-heart procedure in which the surgeon removes a section of the thickened, overgrown septum between the ventricles. Doing this helps to improve blood flow and reduces the level mitral regurgitation. There are different approaches that can be taken, depending on the location of the thickened heart muscle. Surgeons may sometimes perform mitral valve repair at the same time as a myectomy.

If the medications you’ve been prescribed don’t relieve your symptoms a myectomy may be necessary. Most people who have a myectomy experience no further symptoms. Septal myectomy is only available in certain medical centers that specialize in the treatment of hypertrophic cardiomyopathy.

Septal ablation

By injecting alcohol through a long, thin tube (catheter) and into the artery that is supplying blood to the thickened muscle, a small portion of the affected area can be destroyed. This procedure may improve your symptoms, however, possible complications with this procedure can occur. For example, heart block — a disruption of the heart’s electrical system. This requires implantation of a pacemaker.

Implantable cardioverter-defibrillator (ICD)

If you have life-threatening arrhythmias (heart rhythms) such as ventricular tachycardia or ventricular fibrillation your doctor may suggest an ICD. An ICD is a small device that is implanted in your chest like a pacemaker and constantly monitors your heartbeat.

DIAGNOSTIC SERVICES FOR THIS CONDITION

Your doctor will discuss the signs and symptoms you have, or are currently experiencing as well as reviewing your medical and family. Your doctor may order several tests to diagnose hypertrophic cardiomyopathy (HCM).

In order to diagnose hypertrophic cardiomyopathy your doctor will recommend an echocardiogram. This test allows your doctor to see whether your heart muscle is unusually thick or your blood flow is obstructed as well as whether your heart valves are moving normally.

Types of echocardiography include:

  • Transthoracic echocardiogram: This test uses a device called a transducer that is pressed firmly against your skin. This transducer then aims an ultrasound beam through your chest to your heart, generating moving images of the working of the heart.
  • Transesophageal echocardiogram: In a transesophageal echocardiogram, doctors thread a flexible tube containing a transducer down your throat and into your esophagus. From this point, the transducer is able to obtain a more-detailed images of your heart. This test is helpful if it’s difficult to get a clear picture of your heart with a standard echocardiogram or if further examine your mitral valve is required. This test is uncommon and is only done in very few people with hypertrophic cardiomyopathy.

There may be additional tests ordered to search for other effects of hypertrophic cardiomyopathy. This can help your doctor determine the most appropriate treatment for your condition. Examples of these tests include:

  • Electrocardiogram (ECG): Wires (electrodes) attached to adhesive pads on your skin measure the electrical impulses from your heart that help detect enlarged chambers of your heart and abnormal heart rhythms.
  • Treadmill stress test: Your doctor may recommend a treadmill stress test to evaluate symptoms, determine your capacity to exercise, and to see if exercising causes any abnormal heart rhythms to occur. During this test, your heart rhythm, blood pressure and breathing are monitored while you walk on a treadmill.  In people with hypertrophic cardiomyopathy, treadmill stress tests are sometimes performed with echocardiography, however a resting echocardiogram doesn’t show obstructed blood flow.
  • Holter monitor: You may wear a portable ECG that records your heart’s activity continuously over a period of 1 to 2 days and is often done in people with HCM.
  • Cardiac MRI: A cardiac MRI uses magnetic fields and radio waves in order to create images of your heart and is often used in addition to echocardiography.
  • Cardiac catheterization: The insertion of a catheter into a blood vessel in the neck or groin region. The catheter is then carefully threaded to your heart chambers with the careful guidance of an X-ray machine. Cardiac catheterization is used to gather X-ray images (angiograms) of your heart and blood vessels in addition to measuring pressures in your heart. A dye is injected through the catheter to help highlight your heart and blood vessels. This test is rarely used to diagnose hypertrophic cardiomyopathy.

 

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