Myocarditis overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]; Varun Kumar, M.B.B.S.
Overview
Myocarditis is inflammation of the myocardium, the muscular part of the heart. It may present with chest pain, rapid signs of heart failure, or sudden death.
Epidemiology and Demographics
It is generally due to viral infections such as adenovirus, parvovirus B19, hepatitis C, and herpes virus 6 in developed countries and HIV, rheumatic disease in developing countries.
Clinicopathological classification[1]
- Fulminant myocarditis - Occurs after a viral prodrome. May present as acute severe cardiovascular compromise with ventricular dysfunction. The prognosis is good if the patients survive acute illness[2].
- Acute myocarditis - Presents with less distinct onset of illness with ventricular dysfunction. They may progress to dilated cardiomyopathy.
- Chronic active myocarditis - Has a less distinct onset of illness, with clinical and histologic relapses and development of ventricular dysfunction. Histologically, chronic inflammatory changes with mild to moderate fibrosis may be noted.
- Chronic persistent myocarditis - It is of less distinct onset. It is characterized with persistent histologic infiltration and myocyte necrosis without ventricular dysfunction despite the presence of symptoms.
Symptoms
There may be no symptoms. Symptoms may be similar to the flu. If symptoms occur, they may include:
- Palpitations
- Chest pain
- Fatigue
- Fever and other signs of infection including headache, muscle aches, sore throat, diarrhea, or rashes
- Joint pain or swelling
- Pedal edema
- Shortness of breath
- Fainting, often related to irregular heart rhythms
- Low urine output
Diagnosis
Physical examination
Physical examination in patients with myocarditis may reveal tachycardia, cardiac gallop, mitral regurgitation and edema suggestive of cardiac failure. A friction rub too may be noted in presence of concomitant pericarditis.
Electrocardiographic Findings
The ECG findings most commonly seen in myocarditis are sinus tachycardia, diffuse T wave inversions; ST segment elevation may also be present (these are also seen in pericarditis).[3]
Endomyocardial Biopsy
The gold standard is still biopsy of the myocardium, generally done in the setting of angiography. A small tissue sample of the endocardium and myocardium is taken, and investigated by a pathologist by and if necessaryimmunochemistry 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.[3]
Cardiac Magnetic Resonance Imaging
Recently, 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.[4]
Treatment
Bacterial infections are treated with antibiotics, dependent on the nature of the pathogen and its sensitivity to antibiotics. As most viral infections cannot be treated with directed therapy, symptomatic treatment is the only form of therapy for those forms of myocarditis, e.g. NSAIDs for the inflammatory component and diuretics and/or inotropes for ventricular failure. ACE inhibitor therapy may aid in left ventricular remodeling after the inflammation has begun to resolve.
References
- ↑ Lieberman EB, Hutchins GM, Herskowitz A, Rose NR, Baughman KL (1991). "Clinicopathologic description of myocarditis". J Am Coll Cardiol. 18 (7): 1617–26. PMID 1960305.
- ↑ McCarthy RE, Boehmer JP, Hruban RH, Hutchins GM, Kasper EK, Hare JM; et al. (2000). "Long-term outcome of fulminant myocarditis as compared with acute (nonfulminant) myocarditis". N Engl J Med. 342 (10): 690–5. doi:10.1056/NEJM200003093421003. PMID 10706898.
- ↑ 3.0 3.1 Feldman AM, McNamara D (2000). "Myocarditis". N Engl J Med. 343 (19): 1388–98. doi:10.1056/NEJM200011093431908. PMID 11070105.
- ↑ Skouri HN, Dec GW, Friedrich MG, Cooper LT (2006). "Noninvasive imaging in myocarditis". J. Am. Coll. Cardiol. 48 (10): 2085–93. doi:10.1016/j.jacc.2006.08.017. PMID 17112998.