Blood leaks back into the chambers rather than flowing forward through the heart or into an artery. In the United States, backflow most often is due to prolapse. Prolapse is when the flaps of the valve flop or bulge back into an upper heart chamber during a heartbeat. Prolapse mainly affects the mitral valve.
NSTEMI is a shorthand medical term for non-ST segment elevation myocardial infarction. It is one type of myocardial infarction also called heart attack.
Cell death occurs, but some of the heart muscle supplied by the artery survives. Because the ST segment on the ECG does not become elevated in this condition, it is called a non-ST-segment elevation myocardial infarction, or NSTEMI.