Myocardial Infarction Flashcards
Description of a MI
- Myocardium abruptly & severely deprived of O2
- Blood flow decreased by 80-90% (no sx before this) causes ischemia which causes necrosis if blood flow not restored
Which part(s) of the heart does the left anterior descending artery supply?
Anterior left ventricle
Septum
Which part(s) of the heart does the right coronary artery supply?
Inferior left ventricle
Right ventricle
Which part(s) of the left circumflex artery supply?
Lateral left ventricle
Posterior left ventricle
Where is the left main artery?
At the top of the heart = very bad
Aka widow maker
What is collateral blood flow?
Vessels that are developed around a blockage if it builds up over time
Nonmodifiable risk factors for atherosclerosis
Age
Gender
Family history
Ethnicity
Modifiable risk factors for atherosclerosis
Smoking (2x risk)
Sedentary
Stress
Obesity
Elevated cholesterol
HTN
Homocysteine
C-reactive protein
What are homocysteine and C-reactive protein?
Predictive inflammatory markers (esp C-reactive protein)
Tell if there’s an inflammatory process going on in the body
Initial assessment of pt with chest pain (w/in 1st 10 min of arrival)
VS (& pain scale)
ECG
Cardiac enzymes (troponin)
Electrolytes (BUN, creatinine, etc)
Coag studies
CBC
H&P (history & physical: very focused on cardiac)
CXR (w/in 1st 30 min)
*Cardiac presentation of pain or discomfort
Precipitating factors: occurs without cause, early morning, or middle of night
Quality: pain, tightness, pressure, discomfort (may feel like heartburn)
Region/radiation: chest, shoulders, arms, neck, back, jaw, upper abdomen, sub sternal
Severity: scale; not necessarily severe
Timing/treatment: lasts >20 min; relieved by opioids
(If lasts <20 min, usually angina)
Most commonly associated S/S of cardiac pain
N/V
SOB
Diaphoresis
Dizziness
Weakness
Fatigue
Feeling of doom
Syncope
Elevated temp
Elevated BP
Denial
Most common associated S/S of cardiac pain in women
N/V
SOB
Fatigue
Also could have sleep disturbance
Other ways cardiac pain could present:
Pain that is:
Vague ache
Poorly localized
Absent
Sleep disturbance
Back pain
Unexplained fall
Acute delirium
Similarities between Angina and MI cues
Both have sub sternal pain radiating to jaw, neck, ear, and left arm
Differences between angina and MI cues
Angina lasts < 15 min - MI lasts > 20 min
Angina precipitated by activity - MI occurs w/o cause
Angina relieved by rest/NTG - MI relieved by opioids
Angina has few associated S/S - MI has frequent associated symptoms
What is the gold standard for diagnosing an MI?
*Troponin I
Normal value of troponin I
<1.5 ng/ml
Requirements to use fibrinolysis on a pt with MI
- EKG with *Significant ST segment elevation
- *Ongoing chest discomfort: >20 min & < 12 hrs (not helpful if out of this time frame)
- *BP <180/110
- *No use of anticoagulants
- no hx of stroke or TIA, bleeding issues, surgery/trauma in past 3 wks, terminal illness, liver or kidney issues
3 things we look for to classify patients with acute ischemic chest pain
Significant ST elevation
ST depression or dynamic T wave inversion
Non diagnostic ECG, or absent of changes
If pt having significant ST elevation:
Strongly suspicious for injury
= *ST elevation AMI
If pt having ST depression or dynamic T wave inversion:
Strongly suspicious for ischemia
= *High-risk unstable angina / non-ST elevation ACS
If pt has nondiagnostic ECG or absences of changes in ST segment or T waves:
Intermediate / low risk unstable angina
Where is the J point located on an ECK?
Where the QRS meets the ST segment
How to recognize an AMI on an ECG
- *Know what to look for: *ST elevation > 1 mm
- Know where to look: Buddy leads (must be in more than one lead)
On a 12-lead ECG, What does a tall or inverted T wave indicate?
Ischemia
*On a 12-lead ECG, What does an elevated ST segment indicate?
- Injury of myocardial cells
On a 12-lead ECG, What does an abnormal Q wave, elevated ST segment, and inverted T wave indicate?
*Infarction = An involving MI
(Has ischemia - tall/inverted T wave, injury - elevated ST, and infarction - abnormal Q, elevated ST, & inverted T)
What indicates an abnormal Q wave?
More than 1 block wide and more than 1 block deep
Goals of treatment for a MI
*Limit infarct size
*Reprofuse ischemic / injured area
*Prevent/treat complications
Provide emotional support and education
What is the first priority for a pt with a MI?
*Eliminate pain b/c don’t want to stimulate SNS
Go-to opiate for MI
Morphine sulfate
Actions of morphine sulfate
Decreases pain of ischemia
Decreases extension of ischemia (by decreasing O2 demands)
Decreases anxiety
Indications for morphine sulfate
*STEMI
*Consider in NSTE-ACS
- Evidence of *acute pulmonary edema
- Systolic BP >90mm Hg
Precautions of morphine sulfate
- Drop in BP
- Depression of ventilation
- N/V (common) (Zofran often prescribed with)
- Bradycardia
Actions of nitroglycerin
- increase venous dilation
- dilate coronary arteries
- decrease pain of ischemia
- decrease venous blood return to heart
- decrease preload & cardiac O2 consumption
- increase cardiac collateral flow
Indications for nitroglycerin
(Not routinely administered)
- Suspected ischemic chest pain
- Unstable angina (change in angina pattern)
- Acute pulmonary edema (if BP >90 systolic)
Nitroglycerin precautions
Nitroglycerin side effects
*Extreme caution if systolic BP <90 mm Hg
- Extreme caution in RV infarction
*Patient in sitting/lying during administration
Side effects: - Watch for HA, decreased BP, syncope, tachycardia
Type of med that pts who have had a STEMI should discontinue forever
All NSAIDs except aspirin are to be discontinued forever
When should O2 be used to tx MI?
Only if sat is <94% or if indications of hypoxia
Give 3-5 mL/min
When should aspirin be given during an MI?
Everyone gets aspirin except pts with an ASA allergy, right away
Actions of aspirin
Functions of aspirin
Blocks formation of thromboxane A2
Reduces:
- overall mortality from AMI
- nonfatal reinfarction
- nonfatal stroke
Dose of aspirin for MI
160 - 325 mg
2-4 baby aspirin tablets chewed
Precautions for aspirin
PUD or asthma
Bleeding disorders
Severe hepatic disease
When is fibrinolytic therapy indicated?
*Only for STEMI when balloon and stent (PCI) not available
Time must be *> 20 min and < 12 hr
Patients <75 b/c risk of *death from brain hemorrhage increases
Action of fibrinolytic therapy
Breaks up fibrin network that binds clots
Door to drug time if using a fibrinolytic
30 mins
Suffix of fibrinolytic therapy drugs
-plase or -ase
Indications for heparin
- *PTCA or CABG
- with fibrin-specific *lytics X 48hrs (if longer than 48 hrs, use Lovenox)
- *STEMI with/without reperfusion up to 8 days
Mechanism of action of heparin
Indirect thrombin inhibitor (with AT III)
Gold standard for treatment of STEMI
percutaneous transluminal coronary angioplasty (PCI or PTCA) - balloon followed by stent placement
Door to PCI time
*90 min
*(If transfer required - 120 min)
PTCA indications
*STEMI
* NSTEMI
* UA
*Nursing actions for PTCA preprocedure
- informed consent
- shave prep
- IV
- Teaching
- *Allergies (shellfish/iodine)
*Nursing actions for PTCA post procedure
- Check site for *bleeding
- VS
- Cardiac rhythm
- **Check for reocclusion (by looking for ST seg elevation)
- *Circ checks to check for clots/occlusion
- Dye reaction
- Encourage *fluids to flush dye
Indications for Antiplatelet agents (GPIIBIIIA Inhibitors)
ACS
Unstable angina managed medically
UA undergoing PCI
Class for Clopidogrel (Plavix)
Antiplatelet
Actions of *Clopidogrel (Plavix)
*Keeps clots from forming or getting bigger
- inhibits platelet aggregation
- prolongs bleeding time
Nursing considerations for Plavix
*Watch for bleeding, esp when giving with NSAIDs, ASA, Heparin, or Coumadin
Indications for Plavix
*Pt will remain on plavix post-procedure
- With or without lytics for 14 days
- With or without reperfusion
- STEMI - give for 1 year
Indications for beta blockers
STEMI or NSTEMI once stable, but not in early management
(Beta blocker will be added w/in 12-24 hrs after MI and pt will be on it forever to reduce workload of heart)
*Absolute contraindications of beta blockers
Severe CHF/PE
SBP <100 mm Hg
Acute asthma (bronchospasm)
2nd or 3rd degree AV block (b/c SE of beta blockers is heart block)
Indications for ACE inhibitors
*Given indefinitely post MI (b/c prevent abnormal myocyte remodeling)
*Secondary prevention strategies
& other post MI meds
Smoking cessation
BP control
LDL less than 100
Exercise 30 min x 7 day
BMI 18-25%
DM management (HA1C less than 7)
ASA
Plavix (long term)
Coumadin (A fib)
ACE inhibitors
Beta blockers
Aldosterone blockers
When is a Coronary Artery Bypass Graft (CABG) performed?
> 50% occlusion of LCA
Triple vessel disease
Chronic angina refractory to other treatment
Unstable angina
LVF
Lesions not amenable to PCI
PCI failure
Most common post surgical complication
Dysrhythmias (usually resolve with no or very little tx as heart heals)
