Frequency of cardiomyopathy
The most common cardiomyopathy is dilated cardiomyopathy. Its prevalence, or incidence, is 40 cases per 100 000 inhabitants. Men are twice as likely as women to develop the disease.
The disease can occur at any age, but the age peak is mainly between the ages of 20 and 50. The prevalence of hypertrophic obstructive cardiomyopathy is very low, at about 0.2% of the population. The rarest form of cardiomyopathy in the western world is the restrictive form.
In tropical countries, however, it can account for up to 25% of cardiomyopathies, depending mainly on the number of pericardial diseases. Right ventricular cardiomyopathy mostly affects young men and has a prevalence of 1 in 10 000 cases. It also accounts for about 10-20% of sudden cardiac death and is geographically more common in Italy. The number of unclassified cardiomyopathies is extremely rare.
History
The syptoms of cardiomyopathy can be derived from their respective functional limitations. The main symptoms include shortness of breath, fatigue, short-term loss of consciousness, water in the lungs and chest pain. Here, the individual symptoms cannot necessarily be assigned to a specific form of cardiomyopathy, since the different mechanisms often lead to a similar clinical picture.
Shortness of breath and reduced stress are the main complaints with which a patient visits his doctor. Chest pain is more common in hypertrophic cardiomyopathy, for example, because the body does not manage to supply the increased heart mass with additional oxygen under stress. The shortness of breath is caused by a blood congestion in the lungs.
The heart no longer has the power to pump the blood away from the lungs, and the liquid part of the blood can enter the lungs. This ultimately prevents oxygen transport and can also lead to water in the lungs (pulmonary edema). The causes of various cardiomyopathies are manifold and can be assigned to different disease mechanisms.
These include genetic causes, bacterial/viral pathogens and systemic diseases. Dilated cardiomyopathy can be divided into a primary and a secondary form. In the primary form, the disease originates directly from the heart muscle itself and accounts for about 10% of the total cases of dilated cardiomyopathy.
The secondary form of dilated cardiomyopathy can be divided into 3 other major causes, each of which accounts for approximately 30% of the secondary forms. The familial causes are based on a genetic defect, whereby the genetic information is defective, which ensures the production of important heart muscle proteins. These are particularly important for the development of cardiac muscle strength.
Inflammatory processes also play an important role, as bacteria and/or viruses can damage the heart muscle. In addition, the body can also damage the heart muscle through the body’s own proteins (antibodies). This would then constitute a so-called autoimmune disease.
Toxic damage also accounts for 30% of secondary causes. Alcohol seems to play a leading role here and has established itself as the main cause, especially in the industrialized countries. Hypertrophic cardiomyopathy is a hereditary disease and positive family cases can be detected in about 50% of cases.
Meanwhile, 10 gene loci and more than 100 different mutation sites can be identified as the cause of cardiomyopathy, which can lead to hypertrophic cardiomyopathy. As mentioned above, restrictive cardiomyopathy is more common in the tropical regions of the world and can also be divided into primary and secondary forms. The primary form causes a connective tissue remodelling of the heart muscles, which leads to a stiffening of the heart and its inability to work properly.
Löffler’s endocarditis (Löffler’s pericarditis) plays a very important role here. It begins with an inflammation of the heart and ends in a stiffened, functionally restricted heart. The secondary form is usually caused by so-called storage diseases.
Storage diseases occur when a substance remains in the body or cannot be broken down. These substances can be deposited anywhere and thus lead to functional impairment of the respective organ. Storage diseases that lead to a restrictive cardiomyopathy are amyloidosis, sarcoidosis and various fat and sugar storage diseases.
Right ventricular cardiomyopathy is a genetically inheritable disease and can often be confirmed in families. The unclassified cardiomyopathies are usually also based on a genetic defect. Cardiomyopathy is diagnosed after routine cardiological examinations, and in special cases genetic tests are performed to make the final diagnosis.
Routine cardiological examinations include physical examination, electrocardiogram (ECG), echocardiogram, cardiac catheterization, chest x-ray and in some cases heart muscle biopsy. With the physical examination, the cardiologist approaches the diagnosis by looking for typical changes in the body in relation to cardiological disorders. The electrocardiogram allows the doctor to check the electrical function of the heart.Here, the cardiologist can make a statement about the functionality of the electrical lines, and can thus also determine the electrical disturbance typical for a particular cardiomyopathy.
The echocardiogram has become the standard examination in cardiological diagnostics. Here, the physician can obtain a direct picture of the heart and, if necessary, the disorder. In addition, echocardiography allows the physician to see what the blood flow within the heart is like.
The blood flow within the heart says a lot about how functional the heart muscle is. The myocardial biopsy is a procedure in which a small piece of heart tissue is removed in order to later make a statement about the pathological changes of the heart at the cellular level. This examination is often performed in conjunction with other areas of medicine such as pathology.
The cardiac catheterization is often used to rule out that one of the heart vessels is blocked, which could potentially cause typical heart symptoms. The treatment of cardiomyopathy depends on the disorder caused by the cardiomyopathy. Accordingly, the physician must naturally recognize whether the cardiomyopathy is primary or secondary.
The underlying cause of dilated cardiomyopathy is that the ventricle is abnormally dilated and the blood volume cannot be pumped sufficiently. This is where the therapy aims:
- A reduction of the circulating volume
- Lowering of blood pressure and a
- Reduction of heart work.
Thus the heart is protected and can pump more efficiently. The dilatation of the heart can also lead to cardiac arrhythmia, which must also be treated.
During therapy, blood thinners and drugs that regulate the heart rate are used. In severe cases it must be considered whether pacemaker therapy is appropriate. In hypertrophic obstructive cardiomyopathy, the heart fights against a constant obstacle.
This costs the heart a great deal of strength, which can ultimately lead to cardiac fatigue. In order to reduce the work of the heart, beta-blockers and calcium inhibitors are used because they reduce the strength of the heart and improve its filling. If the drug therapy of cardiomyopathy is ineffective, the parts of the heart that represent the obstacle can be rendered ineffective by invasive measures, or removed during a surgical procedure.
Restrictive cardiomyopathy is also treated according to the given symptoms and can be treated similarly to dilated cardiomyopathy or hypertrophic obstructive cardiomyopathy. Since in many cases there is also an inflammation of the heart muscle with involvement of the pericardium, these must also be treated with anti-inflammatory drugs. The unclassified and right ventricular cardiomyopathies can also only be treated symptomatically.