Cardiomyopathy: Definition, Signs, Symptoms, Causes, Mechanism, Diagnosis, Treatment and Prognosis

It is a group of diseases that affect the heart muscle that makes it harder for your heart to pump blood to the rest of your body.

Cardiomyopathy can cause heart failure.

At first there may be few or no symptoms. Some people may have shortness of breath, feel tired, or have swelling in their legs due to heart failure.

An irregular heartbeat can occur, as well as fainting. Those affected are at increased risk of sudden cardiac death.

Types of cardiomyopathy include hypertrophic cardiomyopathy, dilated cardiomyopathy, restrictive cardiomyopathy, arrhythmogenic right ventricular dysplasia, and takotsubo cardiomyopathy (broken heart syndrome).

In hypertrophic cardiomyopathy, the heart muscle becomes enlarged and thickened. In dilated cardiomyopathy, the ventricles enlarge and weaken. In restrictive cardiomyopathy, the ventricle becomes stiff.

The cause is often unknown. Hypertrophic cardiomyopathy is generally inherited, while dilated cardiomyopathy is inherited in one third of cases. Dilated cardiomyopathy can also be the result of alcohol, heavy metals, coronary heart disease, cocaine use, and viral infections.

Restrictive cardiomyopathy can be caused by amyloidosis, hemochromatosis, and some cancer treatments. Broken heart syndrome is caused by extreme emotional or physical stress .

Treatment depends on the type of cardiomyopathy and the severity of the symptoms. Treatments may include lifestyle changes, medications, or surgery. In 2015, cardiomyopathy and myocarditis affected 2.5 million people.

Hypertrophic cardiomyopathy affects approximately 1 in 500 people, while dilated cardiomyopathy affects 1 in 2,500. The result was 354,000 deaths compared to 294,000 in 1990. Arrhythmogenic right ventricular dysplasia is more common in young people.

Cardiomyopathy in children

Cardiomyopathy is the most common reason for heart transplants in children and adolescents. Left untreated, it can lead to life-threatening arrhythmia (irregular heartbeat), heart valve problems, blood clots, and heart failure.

Some types of cardiomyopathy in children can get better with medical treatment. Others can be managed with medication but not cured: These children need lifelong care from a cardiologist.

Children who receive a heart transplant will need ongoing care from a specialized cardiology team. They must also take medications to prevent rejection of the donor heart.

A seriously ill child with cardiomyopathy may temporarily need a respirator to help them breathe. Medicines are given to help the heart pump more easily.

Some of these lower blood pressure and others relax the arteries in the body. Medications can also help remove excess fluid from the lungs or body.

How does the heart work?

The heart is an electrically innervated muscle pump that pushes blood throughout the body through blood vessels. A specialized group of cells located in the upper chamber (atrium) of the heart acts like a pacemaker that generates an electrical impulse.

This impulse begins a sequential electrical stimulation of the heart muscle which then contracts in a coordinated fashion. Consequently, the upper chamber of the heart is stimulated first to contract and send blood to the lower chambers (ventricles) of the heart.

There is a slight delay in the electrical signal that allows the ventricles to fill. The ventricles then contract to pump blood throughout the body. Then there is a slight delay, allowing blood to return to the upper chambers of the heart and refill the heart for the next cycle.

Cardiac output is a measure of heart function that measures the amount of blood that the heart pumps in a specific period of time. Stroke volume is the amount of blood that the heart pumps with one contraction.

The stroke volume multiplied by the number of heart beats per minute is the cardiac output. Normally, the adult heart pumps approximately 5 liters of blood through the body’s blood vessels every minute.

Ejection fraction is a measure of how effective the heart is at pumping blood. It is the percentage of blood in a full ventricle that is pumped from the heart with each contraction.

A normal heart will have an ejection fraction of 60% -70%. This number may decrease if the heart muscle cannot contract or contract properly.

Signs and symptoms of cardiomyopathy

Symptoms of cardiomyopathies can include: fatigue, lower extremity swelling, and shortness of breath.

Other indications of the condition may include:

  • Arrhythmia.
  • Fainting.
  • Dizziness.

When the heart does not contract properly, oxygenated blood is not adequately pumped to the body’s tissues and organs. This inability to deliver oxygen to the body’s tissues can lead to widespread weakness and fatigue.

Other symptoms can include shortness of breath on exercise or chest pain.

If there is an electrical rhythm disturbance associated with cardiomyopathy, abnormal heartbeats can cause palpitations and the sensation of an occasional missed heartbeat or lethal heart rhythms, such as ventricular fibrillation.

Over a period of time, cardiomyopathy can lead to a significant decrease in ejection fraction and cardiac output leading to heart failure.

Symptoms may include: shortness of breath and swelling of the feet, ankles, and legs.

Causes

Cardiomyopathies are confined to the heart or are part of a generalized systemic disorder, often leading to cardiovascular death or progressive disability related to heart failure.

There are many causes of cardiomyopathy that can be classified in various ways. One method to define cardiomyopathy is based on the official definition of the American Heart Association, which is divided into two categories, primary and secondary.

Another method of categorizing the causes of cardiomyopathy is extrinsic and intrinsic, which is most often used when discussing the disease with patients, family members, and caregivers.

Other diseases that cause heart muscle dysfunction, such as coronary artery disease, hypertension, or heart valve abnormalities are excluded. Often times, the underlying cause remains unknown, but in many cases the cause may be identifiable.

Alcoholism, for example, has been identified as a cause of dilated cardiomyopathy, as has drug toxicity and certain infections (including hepatitis C).

Untreated celiac disease can cause cardiomyopathies, which can be completely reversed with early diagnosis. In addition to acquired causes, molecular biology and genetics have led to the recognition of several genetic causes.

A more clinical categorization of cardiomyopathy as “hypertrophied,” “dilated,” or “restrictive” has become difficult to maintain because some of the conditions could meet more than one of these three categories at any particular stage of its development.

The official definition of cardiomyopathy from the American Heart Association in 2006 is as follows:

“Cardiomyopathies are a heterogeneous group of myocardial diseases associated with mechanical and / or electrical dysfunction that generally (but not invariably) exhibit inappropriate ventricular hypertrophy or dilation and are due to a variety of causes that are often genetic.”

“Cardiomyopathies are confined to the heart or are part of generalized systemic disorders, which can lead to cardiovascular death or progressive disability related to heart failure.”

The current definition of the American Heart Association divides cardiomyopathies into:

Primary cardiomyopathies : affecting the heart alone (primary). Primary cardiomyopathies are further divided into inherited (genetic) diseases, those that are acquired, and those that are a combination of both.

What Causes Primary Cardiomyopathy?

Some of the causes of primary cardiomyopathy are:

  • Genetic.
  • Hypertrophic cardiomyopathy.
  • Ion conduction abnormalities.
  • Long QT syndrome.
  • Brugada syndrome.
  • Dilated cardiomyopathy.
  • Restrictive cardiomyopathy.
  • Inflammatory myocarditis.
  • Periparto.
  • Physically and physiologically induced by stress (tako-tsubo syndrome or “broken heart syndrome”).

Secondary cardiomyopathies : which are the result of an underlying disease or condition that affects other parts of the body.

These categories are divided into subgroups that incorporate new genetic and molecular biology knowledge.

What Causes Secondary Cardiomyopathy?

Some of the causes of primary cardiomyopathy are:

  • Gaucher disease.
  • Hemocromatosis.
  • Fabry disease.
  • Drug / alcohol toxicity.
  • Sarcoidosis.
  • Endocrine.
  • Mellitus diabetes.
  • Thyroid problems such as hyperthyroidism, hypothyroidism, and hyperparathyroidism.
  • Acromegalia.
  • Noonan syndrome.
  • Lentiginosis.
  • Nutritional deficiencies
  • Systemic lupus erythematosus .
  • Rheumatoid arthritis.
  • Scleroderma
  • Dermatomyositis.
  • Electrolyte imbalance.
  • Complications of cancer therapy.

What Causes Extrinsic and Intrinsic Cardiomyopathies?

As mentioned above, another method of categorizing the causes of cardiomyopathy is extrinsic and intrinsic (most often used when discussing the disease with patients, family members, and caregivers).

Extrinsic cardiomyopathies : are those that are due to diseases that are not only due to abnormalities in the cells of the heart muscle.

Intrinsic cardiomyopathies : these are due to abnormalities that originate in the heart muscle cell.

Examples

Extrinsic cardiomyopathies

Ischemic cardiomyopathy is a disease of the heart muscle due to inadequate blood supply to the heart muscle and is a common cause of cardiomyopathy.

When the blood vessels of the heart muscle become blocked, the heart muscle cells can be starved of oxygen and not function normally.

An example of this is a heart attack, where a complete blockage of a blood vessel causes muscle cells to die, decreases the total amount of muscle that can be contracted, and cardiac output is compromised.

Poorly controlled high blood pressure (hypertension) can cause abnormal heart muscle function. Diabetes and alcohol abuse.

Intrinsic cardiomyopathies

Examples of extrinsic cardiomyopathies include:

  • Amyloidosis can infiltrate heart cells with amyloid protein.
  • Sarcoidosis can cause inflammation of the cells of the heart.

Viral infections can cause inflammation of the heart muscle (myocarditis) with temporary or potentially permanent damage to heart muscle cells leading to secondary cardiomyopathy.

Dilated cardiomyopathies occur when the fibers of the heart muscle stretch abnormally as the chambers of the heart increase in size and volume.

Stretched muscles lose their ability to contract strongly, similar to an elastic or elastic band that has been overstretched and lose their shape and function.

As the walls of the heart continue to stretch, they can also cause damage to the heart valves between the chambers of the heart, causing blood to regurgitate, resulting in decreased cardiac output and heart failure.

There are many causes of dilated cardiomyopathy including:

  • Infection.
  • Alcohol.
  • Cancer therapies.
  • Chemical poisonings (for example, lead and arsenic).
  • Neuromuscular disorders such as muscular dystrophy.
  • A variety of genetic diseases.

Hypertrophic cardiomyopathy is a genetic or familial disease in which the left ventricular muscle has a predisposition to thicken and impede the normal flow of blood out of the heart.

Hypertrophic cardiomyopathy is the most common cause of sudden death in young people, such as exercising athletes.

Peripartum cardiomyopathy is seen at the end of the third trimester of pregnancy, although it can continue to be a possible cause of cardiomyopathy for five months after delivery. It is more common in obese older pregnant women who develop pre-eclampsia.

Mechanism of cardiomyopathy

The pathophysiology of cardiomyopathies is better understood at the cellular level with advances in molecular techniques. Mutant proteins can alter cardiac function in the contractile apparatus (or mechanosensitive complexes).

Cardiomyocyte abnormalities and their persistent responses at the cellular level cause changes that correlate with sudden cardiac death and other heart problems.

How is cardiomyopathy diagnosed?

The diagnosis of cardiomyopathy begins with the history. Usually the patient’s symptoms consist of complaining of fatigue, weakness, and shortness of breath.

There may also be chest discomfort. Other information may be obtained from past medical history, including history of high blood pressure, high cholesterol, and diabetes.

Taking note of the presence of other underlying diseases, such as sarcoidosis, amyloidosis, thyroid disorders, and rheumatoid arthritis, can be helpful in determining potential causes of cardiomyopathy.

Social history including smoking, alcohol, and drug abuse can also be helpful in making the diagnosis. Family history is often important, especially if there is concern about sudden cardiac death at a young age.

The physical exam will often include checking vital signs, such as heart rate, blood pressure, breathing rate, and oxygen saturation. The healthcare professional can obtain important information from the lung exam to detect fluids and listen to the sounds of the heart.

Murmurs can provide information about leaky heart valves. Examination of the jugular veins in the neck and swelling or fluid in the feet and ankles can be a clue to the diagnosis of heart failure.

Blood tests can be helpful in detecting anemia, electrolyte abnormalities, and kidney and liver function. Other blood tests and laboratory tests may be ordered depending on the clinical situation.

An electrocardiogram (EKG) is a screening test to detect electrical abnormalities in the heart. The electrocardiogram may show evidence of a previous heart attack or ventricular hypertrophy (thickening of the heart muscle).

An ultrasound of the heart (echocardiogram) can help assess heart wall motion function, heart valve integrity, and ventricular ejection fraction. It can also provide visualization of the sac (pericardium) that surrounds the heart.

The chest x-ray may reveal an enlarged or abnormal heart shape or excessive fluid buildup within the lungs.

When to seek medical care for cardiomyopathy

It is not normal to have chest pain or shortness of breath and people who experience these symptoms should seek medical attention.

Swelling of the feet, ankles and legs; increase shortness of breath when exercising; Difficulty lying down and waking up in the middle of the night due to shortness of breath, all can be symptoms of congestive heart failure.

These symptoms should prompt a consultation with a healthcare professional.

It is also not normal to be partially or completely unconscious. A person who passes out due to a heart rhythm disturbance may be in a life-threatening situation.

Treatment

Although the treatment of cardiomyopathy depends on the specific cause, the goal of therapy is to maximize cardiac output, maintain ejection fraction, and prevent further heart muscle damage and loss of function.

Treatment may include a suggestion of lifestyle changes to better manage the condition.

Treatment also depends on the type of cardiomyopathy, it is taking into account the state of the disease, but may include:

  • Medications (conservative treatment) or iatrogenic / implanted pacemakers for slow heart rates.
  • Defibrillators for people prone to fatal heart rhythms.
  • Ventricular assist devices (VADs) for severe heart failure.
  • Ablation for recurrent arrhythmias that cannot be removed with medication or mechanical cardioversion.

The goal of treatment is often to relieve symptoms, and some patients may require a heart transplant.

If cardiomyopathy is associated with electrical disorders, cardiac pacemakers can be implanted to provide stable and coordinated electrical impulses to the heart muscle.

If there is a possibility of sudden cardiac death, an implanted defibrillator may be considered.

The device can recognize ventricular fibrillation, a rhythm that does not allow the heart to contract, and deliver an electrical shock to return the heart to a stable, coordinated rhythm. If indicated, there are some implanted devices that are pacemakers and defibrillators.

Severe cardiomyopathies may not be controlled or treated with mediation, diet, or other surgical interventions. In this situation, heart transplantation may be considered as a final option.

What medications treat cardiomyopathies?

The medications prescribed to the patient will depend on the underlying reason that caused the cardiomyopathy.

If appropriate, angiotensin converting enzyme (ACE) inhibitors and beta blockers can be used to allow the heart to beat more efficiently, which can increase cardiac output.

When there are symptoms of congestive heart failure, diuretics in association with dietary changes and salt restriction can be used to prevent water retention and decrease the workload of the heart.

Should I follow up with my doctor after I have been diagnosed and treated for cardiomyopathy?

Patients with cardiomyopathy often need lifelong care to monitor their heart function. Control of symptoms can be key to optimal outcome.

Blood tests may be needed to monitor medications and other markers in the body.

Echocardiograms and ultrasounds can be used to assess cardiac function, including valve anatomy, ejection fraction, and the function of contraction of the atrium and ventricular walls.

As with all long-term illnesses, constant monitoring is prudent.

Can cardiomyopathy be prevented?

Cardiomyopathy is a term that describes the end result of many diseases and illnesses. The type of heart muscle damage that occurs and the subsequent decrease in the heart’s pumping ability depends on the injury, the amount of damage to the heart, and the potential for recovery.

Some cardiomyopathies are completely preventable, for example alcoholic cardiomyopathy due to long-term heavy alcohol use. Others are unavoidable, such as cardiomyopathy due to a viral infection.

Living a healthy lifestyle will help minimize the risk of developing some cardiomyopathies. This includes maintaining a healthy, balanced diet and following a routine exercise regimen.

For ischemic cardiomyopathy, risk reduction includes life-long control of high blood pressure, high cholesterol, and diabetes.

In patients who are at risk for genetic cardiomyopathy, such as hypertrophic cardiomyopathy, screening echocardiograms may be advisable to prevent sudden cardiac death.

What is the prognosis for a person with cardiomyopathy?

Cardiomyopathy is a prevalent disease. In the United States, up to half a million people develop dilated cardiomyopathy each year. Ischemic cardiomyopathy can be present in up to 1% of the population.

Because cardiomyopathy tends to be progressive, mortality depends on the amount of loss of heart pumping function; And one goal of therapy is to slow down this loss.

Research continues on new medical and surgical treatments, ranging from new drugs, stem cell research, and innovative types of implantable cardiac assist devices. The National Institutes of Health are conducting ongoing clinical trials for patients with cardiomyopathies.