Stressing the body to the point of collapse, as in the Navy Airmen gravity testing by centrifuge. Stimulation of the brain by electical, laser, chemical or other means. The first two methods invoke stress, disorientation, interference with normal body functions, and even trauma in some cases. Too many drugs, or too much G-Force will cause the subject to die. The third method, brain stimulation, can not be considered proof of biological NDEs until science finds tangible biological proof that memory, consciousness, NDEs, etc. exist in the brain, see the Brain Thing for further explanation.
Heart attacks do the same thing.
It is just a difference of method, fortunately the centrifuge can be stopped quickly, a heart attack usually can not. A patient's body temperature was lowered to 50 degrees and the heart stopped so surgery could be done on a brain aneurism. She left her body, looked down upon it, and observed the instrument being used in the operation. When she was revived she described the instrument used and the surgery in detail. The surgeon was amazed, but believed her due to the accurate account she gave.