Myocardial Infarction

  1. What are the causes of MI?
    • Thrombosis
    • Coronary artery stenosis or spasm
  2. How long until cell death/infarction?
    If occlusion causes ischemia lasting longer than 30 to 45 minutes, irreversible cell death and myocardial muscle damage begins to occur.
  3. What arterial occlusion causes right sided/inferior infarction and what is the major concern regarding RX?
    Occlusion of the right coronary artery or one of its branches. The major concern is reduced preload. Nitro is contraindicated in this situation. It is indicated by ST segment elevation in two contiguous leads, II, III and AvF.
  4. Occlusion of which artery causes a lateral wall infarction?
    Circumflex branch of the Left Coronary Artery
  5. Occlusion of which artery results in anterior wall infarction?
    The Left Anterior Descending branch of the Left Coronary Artery. (LAD)
  6. What does ST elevation signify about the muscle damage? If there is an MI with no ST elevation, what does that indicate?
    ST elevation indicates damage to all layers of heart muscle. Non-ST elevation indicates that damage may have only occured to innermost and middle layers of heart.
  7. What are the long term effects of a healed zone of MI?
    Scar tissue forms on the area after a process called remodeling. Contractility is reduced and abnormal wall motion may be present resulting in reduced cardiac output.
Card Set
Myocardial Infarction
MI pathophysiology