commotio cordis

noun

com·​mo·​tio cor·​dis kə-ˈmō-shē-ō-ˈkȯrd-əs 

: concussion of the heart that is caused by a blow to the chest over the region of the heart by a blunt object (as a baseball, hockey puck, or fist) which does not penetrate the body and that usually results in ventricular fibrillation leading to sudden cardiac death if treatment by defibrillation is not immediately given