Myocarditis is an inflammation of the heart muscle. It is a disease of the heart muscle which is structurally and functionally abnormal in the absence of coronary artery disease, hypertension, valvulopathy, congenital heart disease.
The diagnosis of myocarditis is most often a diagnosis of exclusion. Due to the risks, the endomyocardial biopsy is rarely practiced. The incidence of this disease appears to be increasing, possible and because of modern molecular diagnostic techniques.
There are difficulties to detect myocarditis because there are cases with symptoms and cases without symptoms which directly debuts with sudden death. Most commonly are affected young people, average age of developing the disease is 40 years. Myocarditis is slightly more prevalent among men.
Causes of myocarditis
In over half of the cases the cause of inflammation is not detected. Inflammation can occur in a context of infection or not.
Infectious causes of myocarditis
- Viruses such as Enteroviruses (Coxsackie B and Echovirus) with a real affinity to heart muscle. Other viruses that may be responsible: adenoviruses, parvovirus, cytomegalovirus, HIV. Bacterial infections rarely lead to the occurrence of myocarditis: Chlamydia pneumoniae, Corynebacterium diphtheriae, Neisseria meningitis, Salmonella typhi, Vibrio cholerae, Mycoplasma pneumoniae, Mycobacterium spp, Streptococcus spp. In the etiology may be involved fungi: Aspergillus, Candida albicans, Histoplasma, coccidiodes , Cryptococcus, parasites: Trypanosoma cruzi, Toxoplasma gondii, Schistosoma, spirochetes: Borrelia burgdorferi, Leptospira. Trypanosoma cruzi determine myocarditis which occurs in Chagas disease. Borrelia burgdorferi causes carditis that appears in Lyme disease.
Noninfectious causes of myocarditis
- reactions to drugs such as antibiotics (penicillin, cephalosporins, sulfonamides), anticonvulsants, tricyclic antidepressants, vaccines, heart transplantation. Eosinophilic myocarditis occurs in Loffler endomyocardial fibrosis;
- Some drugs may have direct toxic effects: amphetamines, catecholamines, chemotherapy (anthracycline, fluorouracil), interferon alpha drug (cocaine), alcohol;
- damage caused by radiation therapy or hypothermia;
- collagen diseases, diseases of the system (lupus, sarcoidosis, celiac disease, vasculitis).
Signs and symptoms of myocarditis
As I mentioned above, patients with myocarditis may not have any symptoms or they may have nonspecific symptoms. Prodrome suggests a viral infection model with the appearance of fever, sweating, muscle aches, minor digestive symptoms. The patient may present to the doctor complaining of fatigue, dyspnea (shortness of breath, thirst of air), palpitations, chest pain. This chest pain can be confused with acute myocardial infarction. Pain can be caused by a spasm in the coronary arteries and pericarditis which can be associated with myocarditis. Myocarditis causes heart failure in a debut acute or insidious, mostly to people without cardiac history. Arrhythmias and conduction disturbances may cause palpitations.
Markers of inflammation in the myocardium:
- increased number of leukocytes, lymphocytes. Increased number of eosinophils suggests a eosinophilic myocarditis;
- increased erythrocyte sedimentation rate (ESR), C-reactive protein positive, tumor necrosis factor alpha, interleukin;
- myocardial injury: CK and CK-MB are elevated, elevated troponin I and T;
- virus presence: viral serum antibodies, antibodies anti-heart muscle. These dosages are rarely practiced.
Electrocardiogram (ECG) – sinus tachycardia, changes are similar to those of acute myocardial infarction, negative T waves, similar changes like those of pericarditis, arrhythmias. If there are Q waves and left bundle branch block the prognosis is unfavorable.
Chest radiography – heart size may be normal or elevated.
Cardiac ultrasound – helps excluding other causes they cause heart failure. There is no specific sonographic features of myocarditis. May occur, however, a reduction in contractility, increased left ventricular volume and shape. It can detect whether the presence of a thrombus in the left ventricle, an aneurysm or pericarditis.
MRI can be used as a diagnostic test consecutively after a suspected myocarditis and also can be used to locate areas of endomyocardial biopsy.
Coronary angiography is performed in order to exclude coronary artery disease in cases presenting as myocardial infarction with specific ECG changes and enzyme increases.
Endomyocardial biopsy is the gold standard for diagnosis, but it is not indicated in all patients because the sensitivity is low.
Patients with mild myocardial involvement will evolve favorably, those with advanced dysfunction will have different evolution: one-third will remain with cardiac dysfunction, 25% will require transplant or will die, others will recover completely. Can recover completely even those who needed mechanical support.
There is currently no specific treatment proved for myocarditis. Treatment is mainly a supportive one.
Patients will be followed up in the hospital, will stay at rest and completely avoid significant efforts.
Treatment of heart failure is through the use of ACE inhibitors (or angiotensin receptor antagonists), beta blockers, diuretics and possible vasodilators. Digoxin is administered with caution, as it may favor the onset of arrhythmias. If there are aneurysms, thrombosis, atrial fibrillation, embolic episodes it will be needed anticoagulant treatment. Arrhythmias should be treated according to the case and temporarily can be implanted a pacemaker in patients with symptomatic bradycardia or total heart block.
Avoid NSAIDs in the acute phase because they can exacerbate inflammation and increase mortality.
Controversial therapies: immunomodulatory therapy (immunosuppression, linked immunosorbent, passive immunization), antiviral therapy (ribavirin, interferon), antiviral vaccination.