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Myocardial Perfusion
- Supply
- - coronary arteries (wide open)
- - adequate circulation- BP
- - adequacy of blood
- - how well is blood carrying O2
- Demand
- - Inc work or O2 demand
- - myocardial damage or hypertrophy- enlarged
- supply have to meet demand
- demands goes up and we cant supply need we have a problem
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Angina Pectoris
- CP associated w/myocardial ischemia
- insufficient blood supply
- exertion, emotion, exposure to cold can percipitate
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Angina Pectoris- Patho
- ischemia- reduced pumping action---anaerobic metabolism--- lactic acid production--- pain
- ** with restoration of blood flow, no permanant damage
- fix it by giving the cell what they are asking for
- goal: to increase O2 to cell
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Angina- type
- Stable- predictable, stable (you know when it starts and when it will go away)
- unstable- unpredictable , worsening (the demand gets so hgih when you are just resting)
- Variant (Prinzmetal's)- usually due to spasm
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Myocardial Infarction
- Mortality rate 30-40%
- most deaths before reaching the hospital
- 80% of those who reach hospital survive
- In hospital deaths usually occur within first 72 hrs
- * in the first 72 hours most critical
- starts with angina (ischemia) then cells dies
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Acute MI
- Us after sudden CA (coronary artery) occlusion
- & abrupt loss of O2 & blood supply to myocardium
- life threatening
- too many victims wait before seeking help
- those cells can only be ischemic for 20 mins
- total occulusion of cell
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Patho MI
- Atherosclerotic plaques narrow vessel, thrombus occuldes it
- prolonged, unrelieved ischemia causes irreversible damage- necrosis
- cardiac cells can only withstand about 20 mins of ischemia before necrosis starts
- starts w/CAD- thrombus occuldes
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Patho MI 2
- anaerobic metabolism- latic acid- dec contractility
- ANS tries to compenstate- inc imbalance
- acidosis
- leads to conduction disorders and dysrhythmias
- prolonged ischemia-- irreversible cellular damage & necrosis
- (chest pain- go to hospital)
- contractile function lost permanently
- intracellular exzymes released (once cells die they release enzymes- labs will tell you if you had MI)
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Patho MI 3
- necrosis can be in 1 layer (NSTEMI) or all 3 layers (STEMI)
- Infarction process can take up to 6 hrs to complete
- Stemi- ST elevation myocardial infarction
- NStemi- 1 layer of hear
- - cant see on EKG
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Angina or MI?
- Chief Compliant
- - Chest pain **Pain= ischemia
- P- precipating, agravating, allevating
- Q- quality- subjective what does it feel like
- R- Radiating, region, where is it, does it travel
- S- severity (0-10)
- T- time ** TIME= muscle
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Angina or MI
- CEP- serial x 24H- keep doing this
- CK, CKMB- elevates in 4 hours (both elevated in MI- CKMB (heart) norm if not MI)
- Troponin- elevates in 3h, normalizes 5-7d (heart muscles)
- Myoglobin- elevates in 3 hrs (tells muscle damage)
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Angina or MI- EKG
- angina- ST depression
- MI ST elevation
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Q wave formation
if pt has a Q wave they had a MI in the past
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Exercise Tolerance test
- stress test
- exercise incr myocardial o2 demand
- radioactive isotopes may be injected to study function, motion, perfusion- look at rest and exercise and how things are being perfused
- false (+) often in women , false (-) less common
- pain is ischemia
- - if pain failed test
- - didn't have supply to meet demands
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ETT nursing
- NPO, no tobacco 4 hours before test
- flat, comfortable shoes
- loose clothing
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ETT- Persantine or Adenosine
- alternate to exercise
- IV to dilate coronary arteries, then radioactive isotopes
- same pre care as above- NPO, no smoking
- antagonist- aminophylline (stop ischemia, give med if pain comes)
- pt who cant exercise
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