8. Infarction Flashcards
describe subendocardial ischemia
- ischemica is then represented by an inverted T wave
- ST axist shifts away from affected ventricle (ST depression)
describe transmural ischemia
- T wave axis directs toward the area of the LV
- creates hyperacute T waves
- ST segment axis shifts toward the affected area (ST elevation)
what can heart injury show on EKG
- hyperacute T waves which peak 30 min post injury
- no cellular death
general rule for determining if T wave is hyperacute
if you can fit the QRS inside the T, it’s hyperacute
Wellen’s Syndrome
EKG findings
marked T wave inversion (or biphasic T waves) in V2-V4
Wellen’s Syndrome
associated with?
critical stenosis of the LAD artery (widow maker)
what does ST segment elevation represent
that the myocardium is at risk for irreversible infarction
STEMI criteria
- > 1 mm elevation in 2+ limb leads or V4, V5, or V6
- > 2 mm elevation in 2+ precordial leads (V1, V2, V3)
- > 1mm depression in 2+ precordial leads (V1, V2, V3) (posterior MI)
other causes of ST elevation
- benign early repolarization
- pericarditis
- LV aneurysm
- Printzmetal’s Angina
- BBBs
describe the J point
transition from the QRS to the ST segment
causes of ST segment Depression
4
- posterior STEMI
- reciprocal lead changes in STEMI
- NSTEMI/unstable angina
- subendocardial ischemia
Necrosis on EKG
- significant Q waves
- will disappear in 1/4 of pts w/ acute MI
criteria for being a significant Q wave
- width of 1mm
- height is 1/3 total amplitude of QRS
- look at all leads except aVR
what do L and R coronary arteries arise from?
aorta
what does the LCA divide into?
circumflex and anterior descending
what does RCA divide into?
marginal and posterior descending
what does RCA supply?
SA node, AV node, HIS bundle
what does LAD supply
anterior & septal region of LV and septum
what does L circumflex supply?
lateral wall of LA and LV
what does RCA supply
RV and posterior LV
Where to look on EKG for anterior MI? what vessel is impacted?
- V1-V3
- LAD
Where to look on EKG for lateral MI? what vessel is impacted?
- I, aVL, V5, V6
- left circumflex
Where to look on EKG for inferior MI? what shouldn’t be given to these patients?
- II, III, aVF
- suspect RV MI
- nitro
if you suspect inferior/RV MI, what should you next do?
right sided EKG (V1R-V6R)
