Myocardial Ischemia Flashcards
What part of the Heart is most succeptible to Infacrction?
SUBENDOCARDIAL LAYER MOST SUCCEPPTIBLE
Intracavitary blood protects endocardium
Myocardial distance from epicardial coronaries
What factors increase myocardial Oxygen demand?
Heart Rate
Contrzctility
Myocardial Wall tension
What will cause Subendocardial Ischemia?
Oxygen demand exceeds supply. ST segments change
What happens to T waves in myocardial ischemia?
T waves become inverted. Symmetrical!
This is less reliable than ST segments
Hyperacute (tall, peaked) T waves are seen in ful thickness Ischemia(first few minutes)
What does horizontally depressed ST segments tell you?
Subendocardial ischemia
When is ST segment ELEVATION seen?
Transmural ischemia
What happens when you inflate the stent baloon in a coronary vessel?
ST segments rise
Are T waves a good indicatior of Ischemia?
no
What causes Myocardial infarction?
Ischemia, Necrosis, Infarction
Where does necrosis usually start?
Begins in subendocardium and progresses to epicardium. Variable ECG changes
What is the ECG charictaristic of an MI?
ST, QRS and T waves are all affected.
ECG “evolves” during an MI
How wide is a pathologic Q wave during an infarction?
1 small box wide or
>.03 second in duration
What does an inverted P wave mean?
An atrial conduction abnormality
What happens to T waves after an MI?
They stay elevated. Don’t return to normal.
