What is an Acute Myocardial Infarction (AMI)?
Interruption of the blood flow to a portion of the heart that causes myonecrosis (necrosis of cardiac tissue). • How is the diagnosis of AMI made? Identifying symptoms, abnormal ECG changes and increased serum levels of cardiac isoenzymes. • What is the significance of the pain in the patient’s back, left shoulder and arm, as well as the nausea? Heart muscle itself is insensitive to stimuli that in somatic tissue would result in the perception of pain (e.g. cutting). But ischemic events, by diminishing blood flow in coronary vessels and possibly leading to tissue necrosis, produce metabolic byproducts (such as lactic acid). These byproducts are thought to be an important source of painful stimulation of the myocardial nerve endings. The visceral afferent fibers travel within the sympathetic cardiac nerves to the sympathetic trunk on their way to the spinal cord, which they enter through dorsal roots at levels T1-T5. These visceral afferents are thus in the same dorsal roots as the soma
