Myocarditis is an inflammation of the heart muscle. The inflammation can reduce your heart's ability to pump and cause rapid or abnormal heart rhythms (arrhythmias). Infection with a virus usually causes myocarditis. Watch this video to learn all about it. 0:20 Myocarditis 0:30 Causes 1:10 Pathogenesis 6:35 Types of myocarditis 6:45 Giant cell myocarditis 7:48 Eosinophilic myocarditis 8:40 Investigations 9:39 Treatment