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.
The optokinetic reflex (nystagmus; OKN) is an involuntary fixation on objects that are moving in relationship to the head. This is classically observed when looking out of the side of a moving vehicle and has been termed railway nystagmus.