1. Myocardial Ishcemia and Infarction
Chapter 8: St Segment Elevation Ischemia and Q Wave Infarct Patterns

2. Terminology Ischemia Angina Pectoris Necrosis Myocardial Infarction
Epicardium
Subendocardium
TransmuraL
three major coronary arteries

3. Transmural Ischemia Acute Phase St segment elevation
Sometimes tall T waves in certain leads
Acute phase may last hours to days

4. Transmural Ischemia Evolving phase
T wave inversion in the leads where the previously showed ST segment elevation

5. Transmural Ischemia Location Anterior Leads V1 - V6, I and aVl
Inferior
Leads II, III and aVf

6. Anterior MI

7. Inferior MI

8. Recipocity
Compare the anterior leads (V1 - V6, I and aVl)to the inferior leads (II, III and aVf)

9. ST Depression in II, III and aVf St Depression in V1-V6, I and aVl
Anterior MI
Inferior MI
Early Phase
ST elevation
Tall T waves
V1-V6, I and aVl
II, III and aVf
ST Depression in II, III and aVf
St Depression
in V1-V6, I and aVl
Evolving Phase
Inverted T waves in V1-V6, I and aVl
Inverted T waves in II, III and aVf

10. ST Elevation
The ST elevation seen with acute MI is called a “Current of injury”
ST segment elevations are the earliest ECG signs of acute MI

11. Q Waves
Q waves are characteristic markers of infarction. (But not all transmural infarcts lead to Q waves.)
New Q waves of an MI generally appear with the first day or two
With an Anterior MI, these Q waves are seen in one of more of leads V1-V6, I and aVl
With an Inferior MI, these Q waves are seen in one of more of leads II, III and aVf

12. Normal Q Waves large Q waves Small Q waves Horizontal Axis
Vertical Axis
Small Q waves
Horizontal Axis
Small Q waves
Small Q waves
Vertical Axis
Small Q waves
Vertical Axis
Small Q waves

13. Abnormal Q waves in V1 and V2
Tall T waves in V2-V5
Abnormal Q waves in V1 and V2

14. Normal and Abnormal Q Waves
Narrow (less than 0.04 sec), Low amplitude
Abnormal if greater than 0.04 sec in leads I, II, III, aVf or leads V3 - V6.
Wider Q waves in V1, V2, III, and aVf can be normal
Not all Q waves are abnormal, Not all Q waves are the result of MI.

15. Anterior Infarctions FYI
Anterior MI show loss of R wave progression in the chest leads
Anterospetal Infarcts: Loss of R waves in V1 and V2
“Strictly” Anterior Infarcts: Loss of R waves in V3 and V4
Anterolateral or Anteroapical infarcts: abnormal Q waves in V5 and V6

21. Inferior Infarctions
FYI
Abnormal Q waves in leads II, III, and aVF

23. Other FYI Posterior Infarctions Right Ventricular Infarctions
Ventricular Aneurysm
Multiple Infarctions
“Silent” MI
MI with Bundle Branch Block

24. Myocardial Ischemia and Infarction
Chapter 9: St Segment Depression Ischemia and non-Q Wave Infarct Patterns

25. Subendocardial Ischemia
Inner layer
St Segment depression
Anterior leads (I, aVl and V1-V6)
Inferior leads (II, III, and aVf)
May see ST segment elevation in aVr

26. Subendocardial Ischemia

27. Subendocardial Ischemia
Transient ST segment depression
ST segment depression often occurs with angina, which generally returns to baseline when the angina subsides

28. Subendocardial Ischemia
Exercise

29. Subendocardial Ischemia
ST segment depression criteria
1 mm or more
horizontal or downward
lasts 0.08 seconds
depression of only the J point with rapid upward sloping are considered normal.

30. Subendocardial Ischemia
False-Positive
ST depression without disease
False-Negative
Disease without ST depression
Silent Myocardial ischemia

31. Subendocardial Infarction
Persistent ST depression

32. Subendo-cardial Infarction
T wave inversion

33. Non-Specific ST-T changes
FYI
Subtle changes
slight flattening of T wave
minimal T wave inversion

34. Prinzmetal’s Angina Transient ST segment elevation with angina
No Q waves, no T wave inversion
Angina may occur at rest or at night
Coronary artery spasm