 FACT: To extract the heart, the Mayan is seen opening the abdomen  and then reaching up into the chest cavity to bring the heart out.  This would destroy the diaphragm and render breathing so difficult  that the victim would not be just laying there in a gaze/shock  looking at his heart/sacrificers; he would be convulsing violently  (sucking chest wound) as his body tries to fill lungs with air (even  for the brief moment without a heart).