Title: Myocardial Ishcemia and Infarction
1Myocardial Ishcemia and Infarction
- Chapter 8 St Segment Elevation Ischemia and Q
Wave Infarct Patterns
2Terminology
- Ischemia
- Angina Pectoris
- Necrosis
- Myocardial Infarction
- Epicardium
- Subendocardium
- TransmuraL
- three major coronary arteries
3Transmural Ischemia
- Acute Phase
- St segment elevation
- Sometimes tall T waves in certain leads
- Acute phase may last hours to days
4Transmural Ischemia
- Evolving phase
- T wave inversion in the leads where the
previously showed ST segment elevation
5Transmural Ischemia
- Location
- Anterior
- Leads V1 - V6, I and aVl
- Inferior
- Leads II, III and aVf
6Anterior MI
7Inferior MI
8Recipocity
Compare the anterior leads (V1 - V6, I and aVl)to
the inferior leads (II, III and aVf)
9Anterior MI Inferior MI
Early Phase ST elevation Tall T waves V1-V6, I and aVl ST elevation Tall T waves II, III and aVf
Early Phase 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
10ST 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
11Q 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
12Normal Q Waves
Small Q waves Horizontal Axis
large Q waves
Small Q waves
Small Q waves Vertical Axis
Small Q waves Horizontal Axis
Small Q waves
Small Q waves Vertical Axis
Small Q waves Vertical Axis
Small Q waves
13Tall T waves in V2-V5
Abnormal Q waves in V1 and V2
14Normal and Abnormal Q Waves
- Normal
- 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.
15Anterior 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
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21Inferior Infarctions
FYI
- Abnormal Q waves in leads II, III, and aVF
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23Other
FYI
- Posterior Infarctions
- Right Ventricular Infarctions
- Ventricular Aneurysm
- Multiple Infarctions
- Silent MI
- MI with Bundle Branch Block
24Myocardial Ischemia and Infarction
- Chapter 9 St Segment Depression Ischemia and
non-Q Wave Infarct Patterns
25Subendocardial 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
26Subendocardial Ischemia
27Subendocardial Ischemia
- Transient ST segment depression
- ST segment depression often occurs with angina,
which generally returns to baseline when the
angina subsides
28Subendocardial Ischemia
29Subendocardial 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.
30Subendocardial Ischemia
- False-Positive
- ST depression without disease
- False-Negative
- Disease without ST depression
- Silent Myocardial ischemia
31Subendocardial Infarction
32Subendo-cardial Infarction
T wave inversion
33Non-Specific ST-T changes
FYI
- Subtle changes
- slight flattening of T wave
- minimal T wave inversion
34Prinzmetals 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
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