PMT, Johnstons - MI (STEMI, NSTEMI) Flashcards
What are the cardinal symptoms of CVDisease?
- Chest pain/discomfort
- Dyspnea, orthopnea, paroxysmal, nocturnal dyspnea, wheezing
- Cough, hemoptysis
- Fatigue, weakness
- Pain in extremities with exertion (claudication)
STEMI means what?
ST segment Elevation
“Transmural” - involves entire wall with complete interruption of blood flow.
CHD occurs in how many adults?
1/6
Pathobiology of MI
Most MIs are caused by atherosclerosis and rupturing of the plaque.
- STEMI = coronary flow occluded
- NSTEMI or UA = partial coronary occlusion
S/S of MI
- Chest discomfort (more severe than angina)»_space; “heavy, crushing”
- Retrosternal, left, across chest, neck, jaw, left arm, epigastrum
- N/V. Diaphoresis, dyspnea.
- Cannot be relieved by nitro or rest
- 20% are painless»_space; diabetics and elderly!
PE of MI
- May be normal
- S4
- S/S of HF = (S3, crackle, JVD, new murmur)
- BP and HR dependent on location of infarct**
BP and HR in anterior wall infarct v. inferior wall infarct.
Anterior wall infarct (LAD) results in increased sympathetic tone = inc. BP/HR
Inferior wall infarct (RCA) results in decreased vagal/PS tone = dec. BP/HR
What is J point?
Where QRS stops and ST begins.
STEMI on ECG
**ST elevation of 2mm or more in 2 or more contiguous chest or limb leads.
(May be obscured in LBBB.)
Difference in ECG and s/s of NSTEMI v. NSTEMI ACS
Both have: ST depression, T inversion, and chest pain.
NSTEMI has elevated cardiac enzymes, meaning YES, MI.
NSTEMI ACS does NOT have elevated cardiac enzymes, meaning NO MI.
Other than MI, what are causes of ST elevation?
- Pericarditis
- LVH with J point elevation
- Normal variant early repolarization (i.e. young, healthy athlete or young blacks)
Describe ECG evolution in STEMI
Early Acute Phase - T wave amplitude increases; hyperacute pattern; convex upward ST pattern.
Evolved Acute Phase (Chronic Phase) - Resolution of ST elevation variable.
In Evolved Acute Phase (Chronic Phase), resolution of ST elevation variable - this is dependent upon what?
If after two weeks there is still persistent elevation, think what?
- Dependent upon location - 2 weeks for inferior wall infarct. Later for anterior wall.
- Ventricular aneurysm
Normal QRS duration. Normal Q wave duration. Normal QT* duration. Normal ST Normal T
- QRS is 0.05-0.10 sec
- Q wave is less than 0.03 sec
- ST is NEVER normally depressed (, but can be elevated in standard (1mm) and chest (2mm) leads
- Normal QT is 0.40sec (Fatal if prolonged)
- T is postive in L1, L2, V3-V6 (not greater than 5mm in standard, 10mm in chest). Is inverted in AVR.
ST depression means what?
Subendocardial injury. No Q wave.
ST elevation means what?
Subepicardial or transmural injury.
Myocardial ischemia to injury to infarction is indicated by what zones of infarction on ECG?
1) Ischemia - T wave inversion - due to deficient blood supply affecting repolarization
2) Injury - ST segment elevation - shifts (deficient blood supply)
3) Infarction - large Q waves - due to dead tissue causing absence of deloparization current. T waves inverted
Localization of MI/Myocardial ischemia
- LAD is anterior wall ischemia, seen on V1-V6
- RCA is inferior wall ischemia, seen on L2, L3, AVF
- LCX is lateral wall ischemia, seen on L1, AVL
Tombstone T waves indicate what?
Infarction
What do you see on an ECG in a posterior wall infarction?
Reciprocal of anterior wall:
V’s: unusually large R and upright T
Labs in MI
- Inc. WBC 12k-15k (hrs to 2-4 days)
- Inc. CRP
- Inc. BNP
Cardiac biomarkers of necrosis.
What can cause false positives?
Troponin.
Renal failure.
What are non-MI causes of elevated troponin?
CV, pulmonary (pulm embolism, HTN) , neurological (IC-hemorrhage, stroke), shock, renal
Most deaths from aMI are due to what?
VFib
