Myocarditis is the name given to the inflammation of the heart muscle, called myocardial. There are dozens of causes of myocarditis, including infections by viruses, bacteria, protozoa or fungi, drugs, autoimmune diseases, alcohol abuse, cocaine, etc.
The main consequences of myocarditis are the cardiac pump failure, or reduction of the heart to pump blood capacity and the onset of cardiac arrhythmias.
In this article we address the root causes, symptoms and treatment of myocarditis in adults and children with emphasis on viral myocarditis, which is the most common cause.
The heart wall is divided into 3 layers. The innermost layer, which is directly in contact with the blood in the heart cavity is called endocardium. The outermost layer, which surrounds the outside of the heart, the pericardium is called. Between these two thin layers is a thick muscle layer, responsible for the contraction of the heart and blood pumping called infarction.
As mentioned above, any of these layers can become inflamed, leading cadres of endocarditis, myocarditis or pericarditis. When the pericardium and the myocardium inflame together, we call Myopericarditis.
Myocarditis is usually caused by a virus and can have a clinical course varies greatly, ranging from mild frames, with virtually no symptoms until catastrophic situations, with acute heart failure and pump inability of the heart to pump blood.
There are dozens of causes myocarditis, but viral infections are the most common. Viral myocarditis is often responsible for sudden boards myocarditis that arise in children or healthy adults.
At least 20 different viruses have been identified as potential causes of viral myocarditis, among them include:
Viral myocarditis usually occur during or shortly after a viral infection, which can be as simple as a cold. In general, less than 1% of viral infections has just reached the heart, but in Coxsackie B virus infections, the incidence of myocarditis may reach 5%.
In recent years, the incidence of viral myocarditis has been dropped, probably because many of the above listed viruses can be prevented by vaccines that are part of the national vaccination schedule.
Other causes myocarditis
Although viral myocarditis be the main cause of myocarditis, it is not unique. There are dozens of other causes myocarditis, such as:
As mentioned above, myocarditis is usually a mild picture with few or no symptoms. Sometimes the patient confuses the symptoms of a mild myocarditis with the very virus that causes.
The main problem is when the heart muscle dysfunction causes impairment of the same, leading to a frame called heart failure.
In patients who develop symptoms, the most common is fatigue - which in severe cases can occur even with low intensity activities such as walking, bathing, changing clothes or hair comb - swelling of the legs, shortness of breath and cardiac arrhythmias.
In some cases, myocarditis presents fatally, causing a sudden and severe state of heart failure, which leads the patient quickly to a state circulatory shock. If medical care is not fast, the patient progresses to death. It is estimated that up to 20% of sudden deaths in patients younger than 40 years are caused by frames of myocarditis. Death can occur by cardiogenic shock or the emergence of a malignant arrhythmia triggered by inflammation of the myocardium.
Despite the fulminant myocarditis be a catastrophic form of heart failure if the patient is treated in time and can survive the critical phase in the long-term prognosis is good, because most fully recovers and maintains a heart with good operation.
Myocarditis can also introduce less exuberant with slower installation, but progressive heart failure. The symptoms of fatigue, swelling and breathlessness will be installing over the days.
The typical story to think of myocarditis is a relatively young patient, sometimes athlete, without heart disease or risk factors, which develops, about 1 or 2 weeks after a viral frame, an inexplicable framework of heart failure.
In subacute forms of myocarditis, the patient can progress to cardiomyopathy which is an irreversible heart dilation. The opposite of fulminant, subacute form can not lead to death quickly, but the risk of permanent damage to the heart is increased. In subacute forms there is also risk of cardiac arrhythmias, and sudden death also one of the possible outcomes.
Myocarditis should be suspected in all patients with signs and symptoms of heart failure with no apparent cause. Usually, heart failure is a slowly progressive disease with worsening over the years, which occurs in older people, usually with long-standing hypertension and coronary heart disease. A failure that heart that comes quickly in patients without risk factors should always be a warning sign for myocarditis.
Myocarditis should also be suspected in young patients with no risk factors for coronary disease who have elevated troponin levels (an enzyme that indicates heart injury) and ECG changes. Similarly, cardiac arrhythmias which arise in previously healthy patients may also be a signal cardiac muscle inflammation.
Echocardiography is the test used for the diagnosis of heart failure, but it is not able to state with certainty the source of the problem. Magnetic resonance imaging of the heart is a more sensitive test, being able to identify the presence of myocardial inflammation.
Despite all the clues that further examination can provide us, in many cases the certainty of diagnosis is only obtained through a biopsy of the myocardium. This procedure, however, is not routinely performed in less severe cases, because it is an invasive procedure done through cardiac catheterization.
Treatment of myocarditis depends on the cause and severity. Mild cases do not require specific therapy and usually heal spontaneously with time.
In patients with symptoms, heart failure treatment of myocarditis is similar to that recommended for classical heart failure caused by long-standing hypertension or ischemic heart disease. Restriction of salt in the diet, diuretics, beta blockers and ACE inhibitors (ACEI) are the mainstay of treatment.
In myocarditis caused by viruses, antiviral drugs, such as beta interferon, can be used, but they are only effective if started early.
In cases of fulminant myocarditis, the patient needs to be hospitalized in intensive care units to receive all the hemodynamic and respiratory support to acute heart failure of pump demand.
In general, the heart recover completely with time, but some cases may progress to permanent dilation of the cardiac chambers. In such cases, the cardiac insufficiency can not be controlled adequately with medicines, heart transplantation becomes the only treatment option.
