You may feel and remember nothing
Sometimes the heart stops pumping blood and there are no symptoms. Other people may report that they felt dizzy, tired, cold, or weak right before they passed out. An onlooker may notice the person’s eyes rolling back and/or witness a seizure. The heart is tasked with pumping blood to all parts of the body including the brain, and when the brain doesn’t get blood, a person can seize or pass out.