Myocarditis

A factory flooded by its own fire crew

Imagine a car factory (the myocardium) where workers (cardiomyocytes) assemble parts on an assembly line. A virus sneaks in and damages some workers and machines (direct cytotoxic injury). The factory's security team (immune system) rushes in with fire hoses to wash out the invader, but the water floods the entire factory floor, damaging even healthy workers and shorting out the electrical grid (myocardial swelling (edema) and immune infiltration). The conveyor belt (stroke volume) slows because fewer workers can stand up and work. The factory alarm (sympathetic nervous system) blares louder, forcing the remaining workers to move faster (tachycardia), but they're exhausted and some collapse. The electrical wiring (conduction pathways) is now wet and misfiring, causing machinery to spin wildly (arrhythmias) or freeze (heart block). If the flooding is severe enough, the entire assembly line shuts down (cardiogenic shock), and no cars ship out (cardiac output fails).