Heart Issues Pt. 3

myocardial infarction overview

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  • %%heart attack%%: results from interruption in blood supply to part of the heart, causing cell death
  • symptoms include sudden chest pain, shortness of breath, nausea, vomiting, palpitations, sweating, anxiety   * treatments include oxygen (CPR), aspirin, nitroglycerin
  • MI events commonly begin with an acute (temporary, sudden) coronary (blood vessels of the heart) occlusion (blockage)   * underlying atherosclerosis but not always   * almost NEVER happens in someone with a normal circulation
  • can result from   * atherosclerosis plaque causing a local blood clot, called a thrombus, with occludes on artery (primary thrombosis, blood clot)   * local muscular spasm resulting from irritation of smooth muscle by atherosclerotic plaque, or nerve reflexes causing excessive vascular wall contraction (secondary thrombosis, blocked blood vessel)
  • immediately after an acute occlusion, oxygen & blood flow decrease   * coronary ischemia (lack of oxygen)
  • heart cells will begin to die from lack of oxygen, these cells are called “infarcted   * cells walls become leaky & die
causes of death
  • death doesn’t always occur after conclusion of MI. When it does the causes are:
  1. decreased CO

       1. pumping ability is decreased when cells die

  1. damming of blood in the pulmonary blood vessels & pulmonary edema

       1. increased pressure in vasculature when blood is dammed & not moving forward (backup)    2. diminished CO leads to diminished blood flow to kidneys

  1. fibrillation of the heart

       1. 4 factors contribute

             1. acute loss of blood supply to cardiac muscle leads to depletion of potassium (hypokalemia)       2. ischemic muscle causes an “injury current”       3. sympathetic reflexes occur after infarction (increases irritability of heart)       4. muscle weakness causes ventricle to dilate excessively

  1. rupture of the heart

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