Hypertrophic Obstructive Cardiomyopathy

What is Hypertrophic Obstructive Cardiomyopathy?

Hypertrophic obstructive cardiomyopathy (HOCM) is a condition that makes the heart muscle thicker than normal. This condition, sometimes referred to in the past as idiopathic hypertrophic subaortic stenosis, can cause sudden heart failure, particularly in young people including athletes. It does not discriminate, affecting males and females equally, no matter the race.

Mostly, HOCM stems from an uneven thickening in the wall (septum) that separates the left and right sides of the heart, blocking blood flow from the left main pumping chamber (ventricle). This makes it difficult for doctors to detect during regular check-ups, especially in athletes who are believed to be in top shape. Unfortunately, most cases are only discovered after a serious heart-related situation has happened.

The thickening can happen in any part of the left ventricle but usually occurs in the heart’s septum. This can block the normal blood flow out of the heart’s main pumping chamber.

HOCM is a condition that you’re born with or develop because of changes in certain genes. These changes can cause the irregular heart muscle growth. In children, the condition usually doesn’t cause any symptoms, however, it can suddenly cause death in teenagers and young adults.

What Causes Hypertrophic Obstructive Cardiomyopathy?

Familial Hypertrophic Obstructive Cardiomyopathy (HOCM) is primarily a genetic condition that generally runs in families. It’s the most common type of genetic heart disease. However, it can also appear in people with no family history of the disease due to new (or “de novo”) mutations.

HOCM is caused by changes in genes that provide instructions for making one of nine proteins in the heart muscle, such as B-myosin heavy chain, troponin, actin, and titin. These proteins are important for the normal function and structure of the heart. These changes can cause abnormalities in heart muscle cells’ structure and function.

These abnormalities can lead to abnormal force being generated in the heart and irregular conduction of electric signals that control the heart’s rhythm. This results in a type of thickening of the heart’s left side walls (left ventricular hypertrophy) that’s not due to other causes.

HOCM can also be caused by other factors, including:

1. Increased stimulus from the nervous system due to either too much adrenaline-like chemical (catecholamine) being secreted or not enough being taken up

2. Unusually thickened arteries that feed the heart, which may not widen in the normal way. This may cause continuous regions of low oxygen supply to heart muscles (myocardial ischemia), which over time leads to scarring (fibrosis) and response enlargement (compensatory hypertrophy) of the heart
3. Abnormal small blood vessels that prevent the normal contraction of heart muscle fibers (myofibrils).

Risk Factors and Frequency for Hypertrophic Obstructive Cardiomyopathy

Hypertrophic obstructive cardiomyopathy (HOCM) is a heart condition that affects both men and women equally, across all races. Women often experience more symptoms and these symptoms can cause more disabilities. Usually, women are diagnosed at a younger age than men. A study in 1995 reported that HOCM occurs in about 1 in every 500 adults. In the U.S., fewer than 100 deaths per year are caused by HOCM, most often now among athletes at a rate of 1 in every 220,000. While people commonly start showing signs of HOCM in their teens or twenties, some adults may not have any symptoms until their forties to sixties.

HOCM affects men and women equally, and is seen among all races.
Women often have more symptoms which can cause more physical limitations, and are often diagnosed younger.
According to a 1995 study, it occurs in about 1 in every 500 adults.
People often start showing symptoms in their teens or twenties, but some adults may not have symptoms until their forties to sixties.

Signs and Symptoms of Hypertrophic Obstructive Cardiomyopathy

A detailed health history and physical examination are necessary when dealing with Hypertrophic Obstructive Cardiomyopathy (HOCM) and sudden cardiac death. Many patients may show no symptoms at all. However, for those who do, shortness of breath is often the most reported symptom. Patients might also experience symptoms such as lightheadedness, fainting, chest pain, heart palpitations, or dizziness. These signs are often increased with physical activity. In severe cases, the symptoms may mimic those of congestive heart failure such as breathlessness during the night, swelling in the legs, or difficulty breathing when lying flat. The most serious and devastating symptom is sudden cardiac death.

A physical exam can provide clues but is not enough for a definitive diagnosis. Patients could show various signs like a prominent wave in the neck veins, abnormal heart sounds, an unusual double pulse in the neck arteries, and a fast-rising heartbeat that gradually decreases. There could also be abnormal heart murmurs present or signs of heart valve leakage. Despite these signs, the examination of the lungs should typically come back normal.

Shortness of breath
Lightheadedness
Fainting
Chest pain
Heart palpitations
Dizziness
Swelling in the legs
Difficulty breathing when lying flat
Sudden cardiac death

The conditions of certain maneuvers could affect the intensity of heart murmurs in patients. As an example, making a fist could increase the amount of blood in the heart, causing the murmur intensity to decrease. On the other hand, maneuvers that decrease the volume of blood, such as the Valsalva maneuver (forcibly exhaling while keeping the mouth and nose closed) or using diuretic medications, may increase the murmur. Similar effects can also happen as a result of taking beta-blockers, which decrease the force of the heart’s contractions.

Testing for Hypertrophic Obstructive Cardiomyopathy

During a routine checkup, you may undergo different lab studies. These studies are usually normal, but in severe cases, a test called brain natriuretic peptide may show higher than normal levels. Genetic testing is also available. This test is very accurate, but it is typically only used in patients who have a significant family history of heart disease or show clear symptoms of such diseases.

However, the American Heart Association currently advises against regular screenings for genetic markers of heart disease. Another test that might be used is a chest x-ray. While this test could also come out normal, it may show that the muscle on the left side of your heart (left ventricle) is thicker than it should be.

Your doctor may also recommend an electrocardiogram, a test that measures the electrical activity in your heart. This can reveal if your left ventricle is thicker than it should be, and if your heart is beating in an irregular way. Nevertheless, an electrocardiogram can often be normal even if you have heart disease.

The primary tool used to diagnose a specific type of heart disease called Hypertrophic Obstructive Cardiomyopathy (HOCM) is called a 2D echocardiography. This test uses sound waves to create a detailed image of the heart, like an ultrasound. It is accurate about 80% of the time for diagnosing HOCM. The echocardiogram can show important details such as increased blood flow velocity and whether the heart valves are functioning properly. It can also reveal if your heart is stiffer than it should be and can’t fill with blood properly during rest (diastolic dysfunction).

The two main characteristics to look for in HOCM are an unusually thick septal wall (more than 15 mm thick) and an abnormal forward motion of the anterior mitral valve leaflet when the heart contracts. Usually, the posterior sepatal wall is much thicker than the anterior. The narrowing of a part of the heart called the left ventricular outflow tract is also often easily seen with an echocardiogram.

Still, in cases where the echocardiogram is normal or not clear, a Cardiac MRI may be performed. This is considered the most accurate test for diagnosing the properties of the left ventricle wall. Cardiac catheterization, a procedure where a long, thin tube is guided through a blood vessel to your heart to see how well your heart is working, may not be necessary for diagnosis. However, it can provide detailed information about your heart’s structure, including the severity of the obstruction in your left ventricle, and whether or not your heart valves and coronary arteries are functioning well. Lastly, Radionuclide imaging, a test where radioactive substances are detected by special types of cameras, may help identify any significant defects, even if there’s absence of coronary artery disease.

Treatment Options for Hypertrophic Obstructive Cardiomyopathy

If you’re feeling mild symptoms, your doctor will likely recommend changes to your everyday habits as a first step. It’s a good idea to stay away from intense workouts and heavy lifting. If your symptoms persist or become severe, your doctor might prescribe medications. The primary go-to medications are beta blockers; though in some cases, certain types of calcium channel blockers may also help. It’s important to note that certain medications like angiotensin-converting enzyme inhibitors and nitrates should be avoided because they can potentially worsen the condition.

If lifestyle changes and medications aren’t enough to manage your symptoms or if your condition becomes severe (an outflow gradient of 50mmhg or more), the doctor may suggest surgery. Young, healthy patients are generally recommended to undergo a type of surgery called Septal Myectomy.

There’s another technique called Alcohol Septal Ablation that’s typically performed only on older patients for whom traditional, open surgery could be risky. It’s a less invasive procedure that uses a small tube (catheter) to inject alcohol into the part of your heart that’s enlarged, causing some cells to die and the heart muscle to return to a more normal size.

When trying to diagnose a heart condition known as Hypertrophic Obstructive Cardiomyopathy, doctors also consider whether it might be any of these conditions that may present similar symptoms:

Aortic Valve Stenosis
Restrictive Cardiomyopathy
Pericardial Tamponade

What to expect with Hypertrophic Obstructive Cardiomyopathy

Mortality rates for HOCM, or Hypertrophic Obstructive Cardiomyopathy (a heart condition where the heart muscle becomes excessively thick), have gotten better but can still vary between 1-6%. A most common cause of death in young people is sudden death, which often happens during a sports activity.

A recent study found a higher risk of heart complications, like apical aneurysms (a bulging area in the heart wall), cardiac symptoms, and sudden death, in patients who had a midventricular obstruction (a blockage in the middle part of the heart). Because of this, it’s now standard to screen close relatives of HOCM patients to identify those with higher risks.

Patients with HOCM may also develop a variety of irregular heartbeats, known as atrial and ventricular arrhythmias, and are likely to experience heart failure if they have severe diastolic dysfunction, a condition where the heart cannot relax as it should. However, it’s worth noting that symptomatic progression in HOCM patients is inevitable, meaning that everyone will eventually show noticeable signs of the condition.

Possible Complications When Diagnosed with Hypertrophic Obstructive Cardiomyopathy

The complications that may arise from a medical condition known as hypertrophic obstructive cardiomyopathy include:

Irregular heart rhythms by ventricles, the lower chambers of the heart
Heart failure which leads to fluid buildup in the body
Infection of the heart’s mitral valve, known as infective endocarditis
Irregular heart rhythms by the atria or the upper chambers of the heart, known as atrial fibrillation
Blockage of blood flow due to blood clots, referred to as an embolic phenomenon
Unexpected and abrupt death

Frequently asked questions

Hypertrophic Obstructive Cardiomyopathy (HOCM) is a condition that makes the heart muscle thicker than normal, particularly in the wall (septum) that separates the left and right sides of the heart. This can block blood flow from the left main pumping chamber, leading to sudden heart failure, especially in young people including athletes.

According to a 1995 study, it occurs in about 1 in every 500 adults.

The signs and symptoms of Hypertrophic Obstructive Cardiomyopathy (HOCM) include: - Shortness of breath - Lightheadedness - Fainting - Chest pain - Heart palpitations - Dizziness - Swelling in the legs - Difficulty breathing when lying flat - Sudden cardiac death These symptoms may be exacerbated by physical activity and can mimic those of congestive heart failure, such as breathlessness during the night and swelling in the legs. The most serious symptom of HOCM is sudden cardiac death. A detailed health history and physical examination are necessary to diagnose HOCM, as patients may show no symptoms at all. The physical exam may reveal signs such as a prominent wave in the neck veins, abnormal heart sounds, an unusual double pulse in the neck arteries, and a fast-rising heartbeat that gradually decreases. Heart murmurs and signs of heart valve leakage may also be present. However, the examination of the lungs should typically come back normal.

Hypertrophic Obstructive Cardiomyopathy (HOCM) is primarily a genetic condition that generally runs in families. It can also appear in people with no family history of the disease due to new mutations.

Aortic Valve Stenosis, Restrictive Cardiomyopathy, Pericardial Tamponade

The types of tests that are needed for Hypertrophic Obstructive Cardiomyopathy (HOCM) include: 1. Brain natriuretic peptide test: This test measures the levels of a hormone called brain natriuretic peptide, which may be higher than normal in severe cases of HOCM. 2. Genetic testing: This test is used in patients with a significant family history of heart disease or clear symptoms of such diseases. It is very accurate in diagnosing HOCM. 3. Chest x-ray: This test can show if the muscle on the left side of the heart (left ventricle) is thicker than it should be. 4. Electrocardiogram (ECG): This test measures the electrical activity in the heart and can reveal if the left ventricle is thicker than it should be or if the heart is beating irregularly. 5. 2D echocardiography: This is the primary tool used to diagnose HOCM. It uses sound waves to create a detailed image of the heart and can show important details such as increased blood flow velocity, functioning of heart valves, and the stiffness of the heart. 6. Cardiac MRI: This test is considered the most accurate for diagnosing the properties of the left ventricle wall. 7. Cardiac catheterization: This procedure provides detailed information about the heart's structure, including the severity of the obstruction in the left ventricle and the functioning of heart valves and coronary arteries. 8. Radionuclide imaging: This test helps identify any significant defects, even in the absence of coronary artery disease. It is important to note that not all of these tests may be necessary for every patient with HOCM, and the specific tests ordered may vary depending on the individual case.

Hypertrophic Obstructive Cardiomyopathy (HOCM) can be treated through a combination of lifestyle changes, medications, and surgery. For mild symptoms, doctors may recommend changes to everyday habits such as avoiding intense workouts and heavy lifting. If symptoms persist or become severe, medications like beta blockers or certain types of calcium channel blockers may be prescribed. However, medications like angiotensin-converting enzyme inhibitors and nitrates should be avoided as they can potentially worsen the condition. If lifestyle changes and medications are not enough or if the condition becomes severe, surgery may be suggested. Young, healthy patients are generally recommended to undergo a type of surgery called Septal Myectomy, while older patients may be considered for a less invasive procedure called Alcohol Septal Ablation.

The side effects when treating Hypertrophic Obstructive Cardiomyopathy include: - Irregular heart rhythms by ventricles, the lower chambers of the heart - Heart failure which leads to fluid buildup in the body - Infection of the heart's mitral valve, known as infective endocarditis - Irregular heart rhythms by the atria or the upper chambers of the heart, known as atrial fibrillation - Blockage of blood flow due to blood clots, referred to as an embolic phenomenon - Unexpected and abrupt death

The prognosis for Hypertrophic Obstructive Cardiomyopathy (HOCM) can vary, but mortality rates range from 1-6%. Sudden death, often during sports activities, is a common cause of death in young people with HOCM. Patients with HOCM may also develop irregular heartbeats and are likely to experience heart failure if they have severe diastolic dysfunction.

A cardiologist.