Dilated Cardiomyopathy: Description.
Dilated cardiomyopathy (DCM) is a serious disease in which the heart muscles change their structure. It no longer works properly and thus the heart pumps less blood into the systemic circulation during the expulsion phase (systole). In addition, the heart muscle usually can no longer relax properly, so that the phase in which the heart chambers have to fill with blood (diastole) and expand is also disturbed.
This form of cardiomyopathy gets its name from the fact that the left ventricle in particular dilates during the disease. If the disease progresses, the right ventricle and the atria may also be affected. The walls of the heart can become thinner as it expands.
Who does dilated cardiomyopathy affect?
Dilated Cardiomyopathy: Symptoms
Patients with DCM often have the typical symptoms of a weak heart (heart failure). On the one hand, due to its limited performance, the heart does not manage to supply the body sufficiently with blood and thus also with oxygen (cyanosis) – physicians speak of forward failure.
On the other hand, heart failure is also often associated with reverse failure. This means that the blood backs up in those blood vessels that lead to the heart. If the left heart is affected (left heart failure), such blood congestion mainly affects the lungs. If the right ventricle is weakened, blood backs up in the venous vessels that come from throughout the body.
Dilated cardiomyopathy first becomes apparent with the symptoms of progressive left heart failure. Patients suffer from:
- Fatigue and decreased performance. Affected individuals often complain of a general feeling of weakness.
- Shortness of breath on physical exertion (exertional dyspnea). If the cardiomyopathy is already very advanced, dyspnea may also occur at rest (resting dyspnea).
- Tightness in the chest (angina pectoris). This feeling also appears mainly during physical exertion.
In the course of the disease, dilated cardiomyopathy often also affects the right ventricle. In such cases, physicians speak of global insufficiency. In addition to the symptoms of left heart failure, patients then complain of fluid retention (edema), especially in the legs. In addition, the neck veins often become very prominent because blood also accumulates from the head and neck.
Since the structure of the heart muscle changes in DCM, the electrical generation and transmission of impulses to the heart is also disturbed. Therefore, dilated cardiomyopathy is often associated with cardiac arrhythmias. Affected individuals occasionally feel this as heart palpitations. As the disease progresses, the arrhythmias can become more dangerous and trigger circulatory collapse or – in the worst case – even sudden cardiac death.
Because of the impaired blood flow in the atria and ventricles, blood clots form more easily in dilated cardiomyopathy than in healthy people. If such a clot breaks loose, it can enter the arteries with the blood flow and block them. This can lead to serious complications such as a pulmonary infarction or stroke.
Dilated cardiomyopathy: causes and risk factors
Dilated cardiomyopathy can be primary or secondary. Primary means it originates directly in and is confined to the heart muscle. In secondary forms, other diseases or external influences are the triggers of DCM. The heart or other organs are then damaged only as a result of these factors.
Primary dilated cardiomyopathy is in some cases genetic. In a good quarter of cases, other family members are also affected. Often, the triggers of primary DCM are unknown (idiopathic, about 50 percent).
Dilated cardiomyopathy is a form of heart muscle disease that is relatively often caused secondarily. Triggers include, for example:
- Heart muscle inflammation (myocarditis), for example triggered by viruses or bacteria (examples: Chagas disease, Lyme disease).
- Heart valve defects
- Autoimmune diseases, such as systemic lupus erythematosus (SLE).
- Hormone disorders (especially of growth and thyroid hormones).
- Medications: Certain cancer drugs (cytostatics) can cause dilated heart muscle disease as a rare side effect.
- Malnutrition
- Radiation therapy to the chest area
- Congenital diseases affecting the protein structure of the muscles, e.g. muscular dystrophies.
- Environmental toxins: Heavy metals in particular, such as lead or mercury, become lodged in the heart muscle and disrupt cell metabolism.
- Coronary heart disease (CHD). In those affected, the heart muscle permanently receives too little oxygen and therefore changes its structure (ischemic cardiomyopathy). The culprit is a narrowing of the coronary arteries.
- In very rare cases, dilated cardiomyopathy occurs during pregnancy. However, the connections here are still unclear.
Dilated cardiomyopathy: examinations and diagnosis
First, the physician asks the patient about his medical history. He is particularly interested in the patient’s symptoms, when they occur and how long they have been present. It is also important to know whether the patient drinks a lot of alcohol, takes other drugs or has any previous illnesses.
The interview is followed by a physical examination. Some signs of heart failure can be seen by the doctor with the naked eye. For example, the skin of the affected person often appears bluish (cyanosis) due to the chronic lack of oxygen. Pulmonary edema may be noticeable as a rattling sound when listening to the lungs.
Many heart muscle diseases show similar symptoms. To determine exactly what type of cardiomyopathy is present, special diagnostic tests and assistance from medical equipment are needed. The most important examinations are:
- Electrocardiogram (ECG): Many DCM patients have a specific disturbance in the heart’s electrical activity on the ECG called left bundle branch block.
- Chest x-ray: Because of the enlarged left ventricle, the heart appears enlarged on x-rays (cardiomegaly). Lung congestion can also be seen on this.
- Cardiac catheterization. In the course of this method, the coronary vessels can be examined (coronary angiography) and tissue samples can be taken from the heart muscle (myocardial biopsy). Fine tissue examination under the microscope enables a reliable diagnosis to be made.
There are also certain blood values that may be elevated in association with DCM. However, these findings are hardly specific, but occur in many cardiac and also other diseases. For example, high BNP levels generally indicate heart failure.
Dilated Cardiomyopathy: Treatment
If the cause is not known and/or cannot be treated, then only symptomatic treatment of DCM is an option. The priority is then to alleviate the symptoms of heart failure and to delay its progression as far as possible. Various groups of drugs such as beta-blockers, ACE inhibitors and diuretics are available for this purpose. “Blood thinning” medications are designed to prevent blood clots from forming.
In principle, patients with dilated cardiomyopathy should take it easy on themselves physically so as not to overtax the weak heart. However, “dosed exercise” has advantages over complete immobilization.
Dilated cardiomyopathy: disease course and prognosis.
The disease prognosis is unfavorable for dilated cardiomyopathy. Life expectancy and disease progression ultimately depend on the degree of heart failure. Although it is possible to support the heart with appropriate medication, it is not possible to halt or even reverse the progress of the disease. DCM increasingly restricts the everyday life of those affected.
Within the first ten years after diagnosis, 80 to 90 percent of patients with DCM die. Often, the consequences of heart failure or sudden cardiac death are the cause.
The patients themselves can hardly influence the course of the disease. However, those who abstain from drugs and enjoy alcohol only in moderation avoid at least two risk factors for dilated cardiomyopathy.