MI Flashcards
STEMI and NSTEM
What do STEMI and NSTMEI stand for?
STEMI- ST elevation myocardial infarction
NSTEMI- non ST-elevation myocardial infarction
What occurs during AMI (acute myocardial infarction)?
AMI is going to be d/t a COMPLETE interruption of blood flow to all layers of the heart (epicardium–> endocardium), making it transmural.
Usually due to a thrombus.
What is the pathobiology of how MI’s occur?
Most MI’s are d/t athersclerosis, a build up of lipoproteins and plaque formation.
The plaque will then break down and aggregate to form a thrombus, which is rich in platelets.
If coronary blood flow is completely occluded–> STEMI
If coronary blood flow is partially occluded–> UA or NSTEMI.
Besides arthersclerosis, what are other causes of MI?
- Vasospasm
- Vasculitis
- Dissection
- Genetics
What are the clinical manifestations of an MI
Chest pain
Pressure
Naseau
Sweating,
SOB
-Not manifested at one specific place-
Can MI patients be tx with Nitro or rest, like those with angina?
No, they do not respond.
20% of AMIs are painless. Who is more at risk for these?
Diabetic elderly women
What part of an ECG do we see
1. Ischemia
2. Injury
3. Necrosis
Ischemia–> T wave ( will be inverted, tall and peaked)
Injury–> ST segment
Necrosis –> Q wave
How do we recognize a STEMI on a ECG?
Men- ST elevation of 2mm or more at the J point in V2-V3
Women- ST elevation of 1.5mm or more in women in absence of LVH
or 1mm or more in 2 or more chest or limb leads
How do we identigy a NSTEMI?
-Elevated cardiac enzymes
- ST segment is depressed
- T wave is inverted
- Chest pain
How can we identify NSTE-ACS?
(Non ST elevation acute coronary syndrome)
- Cardiac enzymes are normal
- ST segment depression
- Inverted T-wave
- Chest pain
When look at MIs, what part of the ECG do we look at?
QT duration; will tell us about myocardial infarcation (Q wave), myocardial ischemia (T wave) and myocardial injury (ST elevation).
What are the zones of infarction
- Q wave will tell us if there is a presence of dead tissue, which cannot depolarize.
- ST shifts will tell us if there is any injury, which is caused by deficient blood supply and an inability to fully depolarize.
- T wave tells us if there is any ischemia, which is caused by a deficient blood supply making repolarization impaired.
Myocardial infarction to the LAD indicates infarction to what area of the heart?
This can be seen on what leads?
Anterior wall, which can be seen on leads V1-V6
Myocardial infarction to the RCA indicates infarction to what area of the heart?
This can be seen on what leads?
Inferior wall, which can be seen on leads
II, III, AVF, V3R and V6R
Myocardial infarction to the circumflex artery indicates infarction to what area of the heart?
This can be seen on what leads?
Lateral wall, which can be seen on leads
I, aVL, V5 and V6
Myocardial infarction to the posterior descending artery indicates infarction to what area of the heart?
This can be seen on what leads?
Posterior wall, which can be seen on leads
V1, V2 and V3
Ischemia causes _______ of the T wave due to _______.
What will the recipricol effect be on the opposite side of the infarct?
Ischemia will cause an inverted T-wave, due to altered repolarization.
On the opposite side of the heart, the T wave will be upright.
Injury of the muscle causes ________ due to what?
What will the recipricol part of the heart look like?
Injury to the muscle will cause an elevated ST segment.
The recipricol part of the heart will have a depressed ST segment
Infarction of the muscle causes _______, due to what?
What will the recipricol part of the heart look like?
Infarction of the muscle causes a deep Q wave because the tissue is not depoalrization.
Recipricol part of the heart will see a big R wave.
SUMMARY: Infarction, injury and ischemia patterns. What will we see
Infarction- deep Q wave
Injury- ST elevation
Ischemia- Inverted T wave
What do we see during recovery from subacute and chronic stages of an MI?
- ST goes back to nomral.
—then—
- T wave goes back to normal
What is a subendocardial infarction?
Subendocardial muscle is ischemic and injured, but not dead.
Thus, you will see ST elevation or depression.
In the lab, for an MI, you will see
____ WBC
_____ CRP
_____ BNP
increase in all.
BNP–> increase in ventricular wall stress and fluid overload
What are markers of necrosis?
High troponin 1 (cTnI) or T (cTnT) present 1-4 hours after AMI.
Peaks 10-24 hours.
Persists for 5-14 days.
Be careful that renal failure can cause false + cTnT
What will a non-stemi look like?
ST segment is not above baseline.
If anything it is depressed