Cardiomyopathy: Causes, Symptoms, Therapy

Cardiomyopathy: Description

Doctors use the term “cardiomyopathy” to refer to various diseases of the heart muscle (myocardium) in which the heart muscle no longer works properly.

What happens in cardiomyopathy?

The heart is a powerful muscle pump that maintains circulation by constantly drawing in and expelling blood.

Blood that is deoxygenated from the body enters the great vena cava through smaller veins. This vessel carries the blood to the right atrium. From there, it passes through the tricuspid valve into the right ventricle. This pumps the blood through the pulmonary valve into the lungs, where it is enriched with fresh oxygen. It then flows back to the heart, more precisely into the left atrium. Through the mitral valve, the oxygen-rich blood flows into the left ventricle, which finally pumps it into the systemic circulation.

What are the cardiomyopathies?

Basically, doctors distinguish primary from secondary cardiomyopathies. A primary cardiomyopathy develops directly in the heart muscle. In a secondary cardiomyopathy, on the other hand, preceding or existing other diseases of the body also damage the myocardium in their course.

Primary cardiomyopathy can be congenital or acquired, i.e. it can occur in the course of life. There are also mixed forms of congenital and acquired myocardial disease. This subdivision corresponds to the definition of the American Heart Association (AHA) and also takes into account possible causes.

In contrast, the experts of the European Society of Cardiology (ESC) do not use a primary and secondary subdivision. In addition, they do not include, for example, ion channel diseases such as the long-QT syndrome among the cardiomyopathies, since the muscle structure is not altered.

  • Dilated cardiomyopathy (DCM)
  • Hypertrophic cardiomyopathy (HCM), divided into obstructive (HOCM) and non-obstructive (HNCM) forms
  • Restrictive cardiomyopathy (RCM)
  • Arrhythmogenic right ventricular cardiomyopathy (ARVC)

There are also so-called unclassified cardiomyopathies (NKCM). These include, for example, Tako-Tsubo cardiomyopathy.

Dilated cardiomyopathy

Among cardiomyopathies without an immediately identifiable cause, the dilated form is the most common. In this case, the heart loses strength because of overstretching of the heart muscle. Read all about it in the text dilated cardiomyopathy!

Hypertrophic cardiomyopathy

In this type of cardiomyopathy, the heart muscle is too thick and its stretching ability is limited. Learn all about this type of heart muscle disease in the text hypertrophic cardiomyopathy!

Restrictive cardiomyopathy

Since the ventricle can no longer expand properly, less blood reaches the ventricle from the atrium. Consequently, it backs up in the left atrium. As a result, the atria usually enlarge in restrictive cardiomyopathy. The ventricles, on the other hand, are usually normal in size. For the most part, they can continue to pump blood normally during the ejection phase (systole).

Arrhythmogenic right ventricular cardiomyopathy (ARVC)

In ARVC, the muscles of the right ventricle are altered. The heart muscle cells there partially die and are replaced by connective and fatty tissue. As a result, the heart muscle thins out and the right ventricle dilates. This also affects the electrical conduction system of the heart. Cardiac arrhythmias can develop, which occur primarily during physical exertion.

Other cardiomyopathies

In addition to the four main forms, there are other cardiomyopathies. These “unclassified” cardiomyopathies include, for example, non-compaction cardiomyopathy, a congenital form in which only the left ventricle is affected, and stress cardiomyopathy, also called broken-heart syndrome or Tako-Tsubo cardiomyopathy.

There is also the term “hypertensive cardiomyopathy.” It refers to a heart muscle disease that occurs as a result of chronic high blood pressure (hypertension). In hypertensive patients, the heart has to pump more vigorously to move blood into narrowed arteries, for example. As a result, the left ventricle of the heart becomes increasingly thickened and eventually loses its efficiency.

In their definition, the AHA experts therefore also reject the term ischemic cardiomyopathy. This is the term used by physicians to refer in particular to heart muscle diseases that have developed because the heart muscle has been supplied with too little oxygen. This is the case, for example, with coronary heart disease. Its maximum variant is myocardial infarction. Furthermore, cardiomyopathies do not include heart muscle diseases caused by heart valve defects.

Broken-heart syndrome (Tako-Tsubo cardiomyopathy).

This form of cardiomyopathy is triggered by severe emotional or physical stress and usually heals without consequences. Read the most important facts about broken-heart syndrome here.

Who does cardiomyopathy affect?

In principle, cardiomyopathy can affect anyone. No general statement can be made about the typical age at which the disease occurs or the gender distribution. This is because these values are highly dependent on the particular form of cardiomyopathy.

Cardiomyopathy: Symptoms

In all forms of cardiomyopathy, certain parts of the heart muscle, and sometimes the entire heart, no longer work properly. As a result, many patients suffer from typical symptoms of heart failure and arrhythmias.

Fatigue

Due to cardiomyopathy, the heart is sometimes no longer strong enough to pump a sufficient amount of blood into the arteries (forward failure). Patients then often feel tired and listless, and their overall performance decreases. If too little oxygen-rich blood reaches the brain, those affected are very sleepy or even confused. Due to the disturbed, often slow blood flow, the tissue extracts more oxygen from the blood (increased oxygen depletion). This is manifested by cold and bluish discolored skin (peripheral cyanosis) – usually first on the hands and feet.

Edema

If cardiomyopathy causes pronounced heart failure, blood also backs up into internal organs such as the liver, stomach or kidneys. Affected people feel less appetite, feel bloated or have pain in the area of the liver (right upper abdomen). Sometimes the neck veins also become prominent. Symptoms of backward heart failure are also called “congestion signs.”

Cyanosis

At the onset of pulmonary edema, affected individuals have to cough more, increasingly when lying down and thus at night. If the pulmonary edema increases, it becomes increasingly difficult to breathe (dyspnea). They then cough up foamy secretions and become increasingly short of breath. If there is too much fluid in the lung tissue, the blood no longer absorbs enough oxygen. Mucous membranes, such as those of the lips or tongue, therefore often appear bluish (central cyanosis) in cases of pronounced cardiac insufficiency.

Cardiac arrhythmias

If cardiomyopathy causes pronounced heart failure, blood also backs up into internal organs such as the liver, stomach or kidneys. Affected people feel less appetite, feel bloated or have pain in the area of the liver (right upper abdomen). Sometimes the neck veins also become prominent. Symptoms of backward heart failure are also called “congestion signs.”

Cyanosis

At the onset of pulmonary edema, affected individuals have to cough more, increasingly when lying down and thus at night. If the pulmonary edema increases, it becomes increasingly difficult to breathe (dyspnea). They then cough up foamy secretions and become increasingly short of breath. If there is too much fluid in the lung tissue, the blood no longer absorbs enough oxygen. Mucous membranes, such as those of the lips or tongue, therefore often appear bluish (central cyanosis) in cases of pronounced cardiac insufficiency.

Cardiac arrhythmias

When the heart muscle changes, this often also affects the heart valves. In the course of cardiomyopathy, valve defects such as mitral valve insufficiency can occur. They further reduce cardiac output.

In rare cases, cardiac arrhythmias suddenly become so massive in the course of cardiomyopathy that the entire blood circulation collapses. In this case, the heart chambers beat too fast, so that they hardly fill with blood between beats (ventricular tachycardia). Sudden cardiac death is imminent.

Cardiomyopathy: Causes and risk factors

Regarding the causes of cardiomyopathies, it is useful to distinguish primary from secondary forms of the disease.

Causes of primary cardiomyopathies

Primary cardiomyopathies often have genetic causes. Thus, affected individuals have a familial predisposition to cardiomyopathy, which can vary in severity.

Scientific studies in recent years are revealing more and more changes in the genetic material. In hypertrophic cardiomyopathy, for example, these genetic defects impair the formation of special proteins. This disturbs the structure and stability of the smallest muscle unit (the sarcomere) and thus ultimately the function of the heart muscle.

The exact cause of primary genetic cardiomyopathy remains largely unknown. Physicians then speak of idiopathic cardiomyopathy. For example, in about half of patients with restrictive cardiomyopathy, no cause for the disease can be found.

Causes of secondary cardiomyopathies

There are numerous diseases that damage the heart as well as other organs, causing cardiomyopathy. Some medications can also cause cardiomyopathy, such as some anti-cancer drugs.

The causes of a secondary cardiomyopathy are varied and include:

  • Diseases in which certain substances accumulate increasingly in the heart muscle (e.g. amyloidosis, hemochromatosis).
  • Inflammations (e.g. sarcoidosis, infections causing myocarditis)
  • Tumor diseases or their treatment (e.g. radiation, chemotherapy)
  • Severe vitamin deficiency (e.g. severe vitamin C deficiency in scurvy or severe vitamin B deficiency in beriberi)
  • Diseases primarily affecting the nervous system (e.g., Friedreich’s ataxia) and/or skeletal muscles (e.g., Duchenne muscular dystrophy)
  • Metabolic disorders (e.g., diabetes mellitus, severe thyroid dysfunction)
  • drugs, poisoning (toxic cardiomyopathy)

If physicians recognize the cause of cardiomyopathy, they immediately initiate its therapy. In this way, they prevent the progression of the disease. In idiopathic cardiomyopathies, only the symptoms can ultimately be alleviated.

Cardiomyopathy: examination and diagnosis

Medical history and physical examination

The physician first asks the patient about his medical history. To do this, he asks various questions, such as:

  • What are the symptoms?
  • When do they occur?
  • How long have they been present?

Since many cardiomyopathies are partly hereditary, the doctor will ask about any close relatives who also have the disease (family history). He is also interested in whether there have been any sudden cardiac deaths in the family.

During the physical examination, the examiner looks for various cardiomyopathy symptoms. Sometimes even listening to the heart provides the first clues (auscultation). Certain blood values (special proteins such as antibodies and proBNP) also help to assess possible cardiac damage.

Apparative diagnostics

Special medical equipment plays a crucial role in the diagnosis of cardiomyopathy. These include:

  • Electrocardiogram (ECG) that records the electrical activity of the heart. It registers conduction delays or cardiac arrhythmias. Such a measurement is also possible over a longer period of time (long-term ECG) or under stress (stress ECG).
  • Cardiac catheterization: In this procedure, the physician inserts a thin plastic tube into the heart via a vessel. Through the tube, he can take various measurements, e.g., what pressures prevail in the various sections of the heart and the blood vessels near the heart.
  • Biopsy of the heart muscle: As part of the cardiac catheterization, a small piece of the heart muscle can also be removed and then examined under a microscope. This may reveal how the structure of the heart muscle has changed.

In some forms of cardiomyopathy, the genes whose mutations trigger the disease are known. Special genetic tests can be used to screen a patient for such mutations.

Cardiomyopathy: Treatment

Ideally, doctors identify the cause of cardiomyopathy and treat it accordingly (causal therapy). Often, however, the triggering factors are not known or cannot be treated. In such cases, doctors try to relieve the symptoms (symptomatic therapy).

Causal therapy of cardiomyopathy

In causal therapy, physicians prescribe drugs, for example. They eliminate infections, inhibit autoimmune reactions and slow down disturbed metabolic processes. Vitamin deficiencies can be compensated. Further damage caused by viral myocarditis can be prevented by consistent physical rest.

Symptomatic therapy of cardiomyopathy

  • Treat the effects of heart failure: To do this, doctors use various drugs such as diuretics, ACE inhibitors or beta-blockers to relieve the strain on the heart
  • Prevent cardiac arrhythmias: Drugs such as beta-blockers and special antiarrhythmics help here.
  • Preventing the formation of blood clots in the heart: This is done with anticoagulants taken regularly.
  • Physical exertion in moderation and only in consultation with a doctor.

In some cases, doctors also have to operate. For example, they remove parts of the heart muscle (myectomy). In some cases, they implant a pacemaker or defibrillator. As a last resort, when other treatments no longer help, the only option is a heart transplant.

Sports in cardiomyopathy

Whether and in what form exercise is possible in cardiomyopathy depends on the type and severity of the disease.

For some cardiomyopathies, the effects of exercise on disease progression and prognosis have not yet been researched. For example, scientists are currently studying how endurance training affects patients with dilated cardiomyopathy (DCM).

Before patients with myocardial disease begin any physical activity, it is always necessary to consult with the treating physician to avoid unnecessary risks.

If the disease permits light physical activity, the patient should do low-intensity endurance training about three times a week for 30 minutes each time. Sports that are well suited for cardiac patients include:

  • (brisk) walking
  • Walking or Nordic walking
  • Jogging
  • Cycling (on the flat) or ergometer training
  • Hiking
  • Swimming

Increase everyday activity

Below are some tips for a more active lifestyle that will put little strain on the heart:

  • Walk short distances
  • Get off public transportation one stop earlier than normal to increase the distance traveled
  • Ride your bike to work
  • For office workers: work standing up from time to time
  • Take the stairs instead of the elevator (if your heart condition allows this effort)
  • Use a pedometer, the tracking motivates you to move more

But even for everyday activities, the following applies: what level of exercise is good for you and does not overwork the heart should be discussed with your cardiologist in advance.

Cardiomyopathy: disease progression and prognosis

While patients with mild hypertrophic cardiomyopathy have an almost normal life expectancy, dilated and restrictive cardiomyopathy have a far worse course. Without heart transplantation, a large proportion of patients die in the first decade after diagnosis.

Arrhythmogenic right ventricular cardiomyopathy also does not have a good prognosis. Without therapy, about 70 percent of those affected die in the first ten years after diagnosis. However, if the arrhythmias can be suppressed, life expectancy is hardly limited in this form.

Sometimes those affected hardly notice their heart muscle disease for the rest of their lives, or not at all. Then the sudden cardiac arrhythmias of cardiomyopathy in particular become dangerous.