Myocarditis is an inflammatory process of the myocardium that can be caused by viruses, bacteria, fungi, parasites, or toxins. It leads to cellular damage and necrosis of heart muscle fibers as infectious agents invade and cause inflammatory reactions. This can progress to dilated cardiomyopathy as the infection damages more myocytes and the heart becomes dysfunctional with impaired contractility. Management involves bed rest, medications like diuretics and antivirals, and treating symptoms like fever and fatigue.