Questions and Answers
What is the typical timeframe for ECG changes to occur?
Within 2 to 12 hours
What happens to ventricular depolarization and repolarization in injured tissue?
They are altered
What type of tissue can alter ventricular depolarization and repolarization?
Necrotic, injured, and ischemic tissue
How long can it take for ECG changes to occur in some cases?
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What is the underlying cause of ECG changes?
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What percentage of obstruction of the lumen of the artery will cause symptoms in a client?
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What is a potential consequence of 100% occlusion of an artery?
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Why is the left ventricle a common and dangerous location for a myocardial infarction (MI)?
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What type of reflex can cause a client with a myocardial infarction to manifest epigastric pain?
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Why is it essential to assess clients with a myocardial infarction in all organs?
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Which zone of the heart muscle is characterized by irreversible damage?
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What is the earliest detectable cardiac marker for myocardial infarction?
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What is the characteristic ECG finding in the zone of ischemia?
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What is the outcome if adequate oxygenation is restored to the zone of injury?
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Which of the following is NOT a characteristic of the zone of injury?
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What is the significance of a pathologic Q wave on an ECG tracing?
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What is the maximum dose of morphine that can be administered to a patient with pain unrelieved by nitro?
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What is the primary goal of STEMI management?
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Why is morphine administered to a patient with pain?
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What is the target systolic blood pressure for a patient with STEMI?
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What is the purpose of administering a 250 ml NS bolus to a patient with STEMI?
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What is the significance of continuing pain after morphine administration in a patient with STEMI?
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What is the purpose of prescribing clopidogrel to a client with a stent?
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When should a client with a stent take clopidogrel?
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What is a potential benefit of taking clopidogrel after meals?
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What is the purpose of prescribing IV nitroglycerin to a client with a stent?
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What is a potential complication of stent implantation that requires medication therapy?
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Study Notes
Myocardial Infarction (MI)
- Irreversible damage occurs with 100% occlusion, leading to anaerobic metabolism, tissue death, and pain
- Vagovagal reflexes cause epigastric pain in clients with MI
- Severe reduction of cardiac output decreases blood flow to all organs
ECG Changes
- Generally occur within 2-12 hours, but may take 72-96 hours
- Necrotic, injured, and ischemic tissue alter ventricular depolarization and repolarization
- ST elevation indicates no oxygen
- ST depression indicates low oxygen
- T wave inversion occurs in ischemic tissue
Zones of Ischemia, Injury, and Infarction
- Zone of ischemia: reversible, surrounds area of injury, shows ST wave depression and T wave inversion
- Zone of injury: inflamed, injured, but still viable with adequate oxygenation, shows ST wave elevation
- Zone of infarction: irreversible damage, death to heart muscle, shows pathologic Q wave
Cardiac Markers
- Cardiac-specific Troponin T and Troponin I: proteins released during myocardial infarction
- Troponin I: most sensitive early marker, not detectable in people without cardiac injury
- Released 6-8 hours until pain is gone or max 3 doses
Management of MI
- Pain management: 2-4 mg morphine slow IV pump, max 20 mg
- Systolic BP < 110 mmHg: shock position, 250 ml NS bolus to achieve SBP 110, max 1L, monitor breath sounds
- Upon admission: collect cardiac enzymes, strict bedrest
STEMI Management
- Goal: acute episode, door-to-balloon time of 60-90 minutes (PCTA), door-to-drug time of 30 minutes
- Thrombolytic agents: prevent coronary artery occlusion
- Post-stent management: clopidogrel (Plavix) prescribed to prevent GI irritation or bleeding
- IV nitroglycerin: prevents coronary artery vasospasm
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Description
This quiz covers the symptoms and effects of myocardial infarction (MI), including obstruction of artery lumen, anaerobic metabolism, and reduction of cardiac output. It also discusses the importance of assessing clients with MI in all organs, particularly the left ventricle.
