Myocarditis – causes, symptoms, treatment


Myocarditis is a cardiovascular disease characterized by inflammation of the myocardium (heart muscle) which has a wide range of clinical forms (from asymptomatic to life-threatening). The most common etiology is infectious myocarditis (viral, bacterial or fungal). Appears in a health state and can have a rapid evolution towards heart failure or arrhythmias.

Specialists in myocarditis have classified it into several categories, depending on the onset type and evolution, as follows:

  • Fulminant myocarditis – occurs after a viral infection, clinically manifested, with altered ventricular function and in the cardiac muscle there are numerous foci of inflammation, necrosis and degeneration of fibers. Evolution is either toward spontaneous healing or death.
  • Acute Myocarditis – it has no signs or symptoms as obvious as fulminant myocarditis or ventricular damage but is very important. Evolves frequently to dilated cardiomyopathy.
  • Chronic active myocarditis – this form has a long evolution, with frequent reactivation.
  • Chronic persistent myocarditis– does not present ventricular dysfunction, despite the fact that there are clinical signs and symptoms of myocardial damage (retrosternal pain, palpitations) and there are foci of myocyte necrosis.
  • Myocarditis is a condition that occurs mainly in younger people (average age of patients is 42 years), in immunocompromised patients and pregnant women.

Causes of Myocarditis

Myocarditis is a disease of infectious nature:

  • viral infections: coxsachie, cytomegalovirus, hepatitis C virus, parvovirus, herpes viruses;
  • Bacterial infections: chlamydia, mycoplasma, Streptococcus, Treponema;
  • Fungal infections: aspergilllus, candida, Histoplasma;

The majority of cases (over 50%) are classified as idiopathic, although often is suspected the viral etiology. Even with sophisticated diagnostic techniques, many cases of myocarditis still have an unknown etiology.

Other causes:

  • Systemic Inflammatory Diseases;
  • Kawasaki disease;
  • Crohn’s disease;
  • Systemic lupus erythematosus;
  • Ulcerative colitis;
  • Wegener’s granulomatosis;
  • Thyrotoxicosis;
  • Scleroderma;
  • Rheumatoid arthritis;
  • Certain medications;
  • Antibiotics (penicillin, chloramphenicol, sulfonamides);
  • Antihypertensives (methyldopa, spironolactone);
  • Anticonvulsants (phenytoin, carbamazepine);
  • Amphetamine;
  • Cocaine;
  • Allergic reactions to certain substances;
  • Catecholamines;
  • Heavy metals;
  • Exposure to chemicals;
  • Hydrocarbons;
  • Carbon monoxide;
  • Arsenic;
  • Lead;
  • Mercury;
  • Cobalt;
  • Exposure to physical agents;
  • Radiation;
  • Heatstroke;
  • Hypothermia.

Symptoms of Myocarditis

Myocarditis may be asymptomatic or paucisymptomatic. Most patients who present with myocarditis complain about:

  • Palpitations;
  • Chest pain (with characters like heart pain or angina);
  • Fatigue;
  • Fever, and other signs of infection: myalgia, headache, hoarseness, diarrhea, skin rash, chills;
  • Pain or swelling in the joints;
  • Leg edema;
  • Shortness of breath;

Less common symptoms are:

  • Syncope, fainting (as a result of arrhythmias);
  • Quantitatively reduced micturition.

Some patients may present with heart failure occurred after a few years after myocarditis.

Investigations

On physical examination of the patient the doctor may find:

  • Lymphadenopathy, arrhythmias;
  • Maculopapular eruption of skin and signs of cardiac disease (for eosinophilic myocarditis);
  • Sustained ventricular tachycardia with rapid progression to heart failure (in the case of giant cell myocarditis);

In general, patients with acute myocarditis present in stages of decompensated heart failure.

In these situations cardiologic examination will record:

  • Abnormal rhythms, tachycardia and cardiac murmurs;
  • Leg edema;
  • Lungs hyper-loaded with liquid;

Tests and investigations that can help your doctor determine the diagnosis of myocarditis are:

  • blood counts (for possible infections);
  • Acute phase reactants (ESR, CRP) which usually are increased, and C-reactive protein is positive;
  • immunological tests;
  • serological tests – increased Ig M;
  • Chest radiography;
  • Electrocardiogram often shows nonspecific changes: conduction disorders, ventricular arrhythmias;
  • Myocardial Biopsy represents the gold standard in the diagnosis of myocarditis. It involves harvesting a very small fragment of tissue and its structural particularities will be observed under the microscope. Histo-pathological aspect is a interstitial myocarditis with an inflammatory infiltrate (rich in macrophages and lymphocytes), with areas of necrosis and disorganized tissue architecture.
  • Echocardiography: is done to exclude other causes of heart failure (valvular, congenital causes, amyloidosis) and to assess the degree of cardiac dysfunction. Can visualize expansion inflammation and make the differential diagnosis between the acute and fulminant myocarditis.
  • Determination of cardiac enzymes (creatine kinase and cardiac troponin). Are indicators of cardiac myonecrosis. Cardiac Troponin is increased for over 50% of patients with myocarditis diagnosed by biopsy.
  • Cardiac angiography is indicated to rule out ischemic heart disease as the cause for heart failure (especially in cases where early symptoms are similar to those of myocardial infarction).

Treatment of Myocarditis

Inotropic Medicines (those that stimulate contractility and heart rate) are indicated if there is important hemodynamic decompensation. Should be used very cautiously because they are considered to be proarrhythmic (the ability to induce arrhythmias).

Treatment of myocarditis (both acute and chronic) has goals as heart congestion reduction, improving heart function, and also sustaining of some hemodynamic parameters.

Some patients require anticoagulation therapy (in particular to prevent thrombus formation). In certain cases are indicated antiarrhythmics.

Immunosuppressive therapy has not been shown to influence the natural course of myocarditis, but some doctors prefer it (there are studies that suggest this for particular patients with giant cell myocarditis and sarcoidosis).

Currently, the most commonly used drug classes are:

  • Vasodilators: decrease the systemic vascular resistance. This is manifested by beneficial perfusion through various organs and tissues (especially the myocardium). The administration of nitroglycerin is preferred because it acts very quickly (within minutes) and the condition of the patient improves rapidly.
  • Angiotensin Converting enzyme inhibitors are recommended for use especially after stabilization of symptoms of acute heart failure. It slows down the progression to congestive heart failure.
  • Diuretics: reduces the fluid loading of the organism.

Surgical treatments (implantation of intraventricular devices or cardiac transplantation) are indicated in patients whose disease does not respond to medical treatment. Heart transplantation is particularly beneficial in patients with giant cell myocarditis (diagnosis established at biopsy). 5-year survival rate is 71% after transplantation.


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  1. February 24, 2015

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