A medical illustration showing the cross-sectional view of the heart muscle following the progression of a myocardial infarction and the body's response. With the initial ischemia, troponin proteins are released from the cardiac muscle cells as the tissue dies. Neutrophils then rush to the ischemic site to break down and remove dead tissue with the progression of the ischemia. Once the ischemia has become severe, macrophages arrive to remove debris as the tissue continues to die.