MI Flashcards
coronary arteries of the heart
RCA, acute marginal, posterior descending, left anterior descending, diagonals, oblique marginal, circumflex, LCA
ischemia
lack of O2
infarct
death of cells due to lack of oxygen
causes of acute MI
lumen narrowing, reduced blood flow, dec O2 delivery to muscle
consequences of dec O2 to the heart
plaque fissure or hemorrhage, coronary artery thrombosis (WBC, platelets, lipids), coronary artery spasm
factors influencing the amount of ischemia
Size of the artery Degree of collateral flow Status of fibrinolytic system (anticoagulants: lovonox, aspirin, etc.) Vascular tone Myocardial oxygen demand
phase 1/4 of AMI
Ischemic Insult – lasts 4 hrs form the time the blood stops. Some of the area can be saved if perfused
phase 2/4 of AMI
Coagulation Necrosis – 4-48 hrs after blood has stopped, the cell is dead and there is no recovery
phase 3/4 of AMI
Healing – 48- 72 hours
phase 4/4 of AMI
Scarring – 1 wk after the infarct and can last 2 wks to several months
1 goal of treatment of AMI
early dx and re- perfusion!, time = muscle, preserve myocardial function
Q- wave MI
Usually full-thickness of myocardium involved (transmural) usually when ST elevation occurs
Sent straight to cath lab
non Q- wave MI
Usually partial thickness (subendocardial)
mechanisms for dx of AMI
History (fam and health) Physical Exam ECG Serum Markers ECHO Angiography
pertinent hx for dx of AMI
Chest Pain / Discomfort (75-80% of people experience sx with MI)
May occur at rest (Usually severe, prolonged)
May radiate
May feel like GI problem
***25% don’t have discomfort!
most common associated sx of AMI
Indigestion Nausea / Vomiting Diaphoresis Palpitations Dyspnea / Fatigue
other sx to consider for AMI with elderly, DM, and women
Atypical Presentations
Anginal equivalents may mimic other conditions
AMI and PE
*extremely variable
important to est hx and monitor closely
12- lead EKG importance
Confirmatory in ~80% of AMI’s Obtain STAT if MI is suspected Serial ECG’s ST segment elevation is indicative of acute injury ST segment depression may indicate NQWMI
Myocardial injury criteria
injured area remains electrically + causing elevated ST segment, causes no blood flow
myocardial infarct
causes deep Q wave
AMI serum marker: creatine kinase MB isoenzyme (CK-MB)
specific to heart muscle and lower sensitivity, not as reliable as trop
appears: 3-12 hrs
peaks: 24 hrs
returns: 48-72 hrs
AMI serum marker: troponin
gold standard in dx, downside is delayed reading
appears: 3-12 hrs
peaks: 24-48 hrs
returns: 5-14 days
AMI serum marker: myoglobin
highly sensitive but not specific to the heart (indicates breakdown of skeletal muscle)
appears: 1-4 hrs
peaks: 3-15 hrs
returns: 20-24 hrs
CBC
Leukocytosis is common (due to injury/ inflammation)
c- reactive protein (inflammatory marker)
May be elevated
Usually order HS-C reactive Protein
Not definitive
Appears after MI and unstable angina
Echo
Can detect regional wall motion abnormalities
Can define extent of infarction and assess overall LV or RV function
Helps when the ECG is non diagnostic but is more time consuming
Left Ventricular Function=Ejection fraction (normal 55-70)
EF <40 = heart failure
EF indicative of HF
<40
therapeutic O2 for tx AMI
*place O2 to prevent tissue damage
esp with <95%
should be above 90%
pain relief for pt with AMI
- nitro 2. morphine
opens vessels and relieves pain
MONA
morphine, O2, nitro, aspirin
*not in order
Angiography
Defines coronary anatomy / extent of disease
Most acute MI’s go to Cath Lab for emergency intervention
PTCA (Percutaneous coronary angioplasty)
Stents
Atherectomy – remove plaque
reperfusion strategies for AMI
Primary Angioplasty / Stent
Fibrinolytic Therapy within 12 hours of symptoms onset in patient with STEMI
Aspirin and Antiplatelet Therapy (Antiplatelet: Plavix, GP IIb/IIIa receptor antagonists (Integrilin, Aggrestat, ReoPro))
Heparin / Lovenox
CABG (coronary artery bypass graft)
management for inc O2 demand
Supplemental Oxygen
BP control
Heart Rate control
Nitroglycerin (common assoc HA “nitro HA”
Beta-Blockers early (2- 24 hours)
ACE Inhibitors if LVSD (left ventricle systolic dysfunction) (<40)
complications of AMI
Sudden Cardiac Death Dysrhythmias (cause of sudden death) *v-fib Left Ventricular Failure causing poor organ perfusion Hemodynamic Alterations Infarct Expansion / Remodeling LV Aneurysm Valve Rupture Ventricular Septum or Free Wall Rupture Pericarditis
hx indicative for coronary risk factors
CAD Angina Heart failure Cardiac Surgery Cardiac medications
change in BP due to AMI
Hypotensive <90 systolic (blood loss or medication)
Hypertensive (blockage, pain, anxiety)
change in HR due to AMI
< 60 can be due to brady dysrhythmia or heart block
> 100 can be due to CHF or a tachy dysrhythmia
Irregularities
assessment of JVD
Distention: fluid overload
assess with HOB at 30 degrees sitting up
best indicators of I&O?
weight
variations in heart sounds with AMI
Pericardial friction rub can be 2-3 days after QWMI
Valvular murmurs due to papillary muscle dysfunction
respiratory PE in pts with AMI
Breath Sound usually fine and clear unless CHF
abdomen PE and AMI
Nausea/vomiting
genitourinary and AMI
Urine Output < 30 cc/hr due to
change in peripheral perfusion with AMI (dec)
Cool, pale, diaphoretic. weak, thready pulses
Decreased CO
Mottling in lower extremities
change in temp with AMI
Slight increase due to inflammatory response for 48- 72 hours
steps to take to detect sig changes in cardiovascular status or complications
Complete and document cardiovascular assessment q 4 hours and PRN Assess and document HR and rhythm Assess for new murmur or S3 or S4 Assess for new crackles Assess for reduced activity tolerance
decrease thrombogenicity
Administer anticoagulants
Usually Plavix and Aspirin
For heparin has PT and PTT and may also be on coumadin
For coumadin need INR of 2-3 (therapeutic range)
assess for DVT
color girth temperature of extremities presence of tenderness cords in lower extremities
pt sx that would require immediate medical attentions
Increase in frequency or duration of angina
Shortness of breath, diaphoresis, change in quality or duration of pain
Recurrent angina previously controlled by medications
Heart palpitations or fainting
Side effects of difficulty in maintaining medication regimen
guideline for pts who require nitro
Every 5 minutes X 3, then call 911
If never had before take one and call 911
beta blockers
(-olol) dec HR and BP, dec workload of heart
A client is c/o substernal pain that spreads to the left side and back and is usually relieved with sitting upright and taking an anti-inflammatory drug. You suspect the client is most likely experiencing?
Pericarditis bc relief with anti-inflammatory and change of position
heart healthy diet for AMI pt
low fat, low cholesterol, low sodium
What percentage of deaths from coronary artery disease is directly attributable to cigarette smoking?
21%
