A large number of causes of myocarditis have been identified, but often a cause cannot be found. In Europe and North America, viruses are common culprits. Worldwide, however, the most common cause is Chagas' disease, an illness endemic to Central and South America that is due to infection by the protozoan Trypanosoma cruzi.[10] Many of the causes listed below, particularly those involving protozoa, fungi, parasites, allergy, autoimmune disorders, and drugs are also causes of eosinophilic myocarditis.
Infections[edit] => Viral (adenovirus, parvovirus B19, coxsackie virus, HIV, enterovirus, rubella virus, polio virus, cytomegalovirus, human herpesvirus 6 and possibly hepatitis C)&Protozoan (Trypanosoma cruzi causing Chagas disease and Toxoplasma gondii)&Bacterial (Brucella, Corynebacterium diphtheriae, gonococcus, Haemophilus influenzae, Actinomyces, Tropheryma whipplei, Vibrio cholerae, Borrelia burgdorferi, leptospirosis, and Rickettsia, Mycoplasma pneumoniae)&Fungal (Aspergillus)&Parasitic (ascaris, Echinococcus granulosus, Paragonimus westermani, schistosoma, Taenia solium, Trichinella spiralis, visceral larva migrans, and Wuchereria bancrofti
Bacterial myocarditis is rare in patients without immunodeficiency.
Toxins[edit] => Drugs, including alcohol, anthracyclines and some other forms of chemotherapy, and antipsychotics, e.g. clozapine, also some designer drugs such as mephedrone[12
Immunologic[edit] => Allergic (acetazolamide, amitriptyline)&Rejection after a heart transplant&Autoantigens (scleroderma, systemic lupus erythematosus, sarcoidosis, systemic vasculitis such as eosinophilic granulomatosis with polyangiitis, and granulomatosis with polyangiitis, Kawasaki disease)&Toxins (arsenic, toxic shock syndrome toxin, carbon monoxide, or snake venom)&Heavy metals (copper or iron
Physical agents[edit] => Electric shock, hyperpyrexia, and radiatio
Myocarditis refers to an underlying process that causes inflammation and injury of the heart. It does not refer to inflammation of the heart as a consequence of some other insult. Many secondary causes, such as a heart attack, can lead to inflammation of the myocardium and therefore the diagnosis of myocarditis cannot be made by evidence of inflammation of the myocardium alone.[15][16]
Myocardial inflammation can be suspected on the basis of electrocardiographic (ECG) results, elevated C-reactive protein (CRP) and/or erythrocyte sedimentation rate (ESR), and increased IgM (serology) against viruses known to affect the myocardium. Markers of myocardial damage (troponin or creatine kinase cardiac isoenzymes) are elevated.[10]
The ECG findings most commonly seen in myocarditis are diffuse T wave inversions; saddle-shaped ST-segment elevations may be present (these are also seen in pericarditis).[10]
The gold standard is still biopsy of the myocardium, in general done in the setting of angiography. A small tissue sample of the endocardium and myocardium is taken, and investigated by a pathologist by light microscopy and—if necessary—immunochemistry and special staining methods. Histopathological features are myocardial interstitium with abundant edema and inflammatory infiltrate, rich in lymphocytes and macrophages. Focal destruction of myocytes explains the myocardial pump failure.[10]
Cardiac magnetic resonance imaging (cMRI or CMR) has been shown to be very useful in diagnosing myocarditis by visualizing markers for inflammation of the myocardium.[17] Recently, consensus criteria for the diagnosis of myocarditis by CMR have been published.[18]
Play media Ultrasound showing cardiogenic shock due to myocarditis[19]&Play media Ultrasound showing cardiogenic shock due to myocarditis[19]&Play media Ultrasound showing cardiogenic shock due to myocarditis[19
The signs and symptoms associated with myocarditis are varied, and relate either to the actual inflammation of the myocardium or to the weakness of the heart muscle that is secondary to the inflammation. Signs and symptoms of myocarditis include the following:[10]
Chest pain (often described as "stabbing" in character)&Congestive heart failure (leading to swelling, shortness of breath and liver congestion)&Palpitations (due to abnormal heart rhythms)&Sudden death (in young adults, myocarditis causes up to 20% of all cases of sudden death)[11]&Fever (especially when infectious, e.g. in rheumatic fever)&Symptoms in young children tend to be more nonspecific, with generalized malaise, poor appetite, abdominal pain, and chronic cough. Later stages of the illness will present with respiratory symptoms with increased work of breathing, and is often mistaken for asthma
Since myocarditis is often due to a viral illness, many patients give a history of symptoms consistent with a recent viral infection, including fever, rash, diarrhea, joint pains, and easily becoming tired.
Myocarditis is often associated with pericarditis, and many people with myocarditis present with signs and symptoms that suggest myocarditis and pericarditis at the same time.