Ischemia And Infarction

Question 1

What does an MI imply and how can it be diagnosed?

Answer 1

1. Implies a complete occlusion of a coronary artery
2. Diagnosed with an EKG

Question 2

What are the sequence of events to an MI?

Answer 2

1. Ischemia
   *inadequate tissue perfusion
2. Necrosis
   *infarction (vessels are dying)
3. Fibrosis
   *scarring (only if the blood supply is not restored in time)

Question 3

What are some ways that the EKG changes with ischemia/infarction?

Answer 3

1. Appearance of pathological Q waves that are >1/3 R wave
2. ST elevation and depression
3. T waves
   *peaked
   *flattend
   *inverted

Question 4

What is the first change that occurs on an EKG during an acute MI?

Answer 4

1. T-wave changes
   *peaked T wave followed by inverted T wave
   *represents myocardial ischemia (can be reversible)
2. T-wave changes due to infarct are usually permanent

Question 5

What is the second change that happens during an Acute MI?

Answer 5

1. ST segment elevation
   signifies acute myocardial injury
   can return to baseline within a few hours
   ****elevation of >1mm of the ST segment in 2 contiguous leads

Question 6

What do Q waves represent?

Answer 6

1. Necrosis
   *irreversible
   *Diagnostic of MI (After the fact)
   *Area of no electrical activity

Question 7

What is the criteria of significant Q waves?

Answer 7

Q wave >1mm wide (0.04s) OR
>1/3 height of R in same QRS complex

Question 8

What lead should you ignore looking at?

Answer 8

AVR

Question 9

What are the EKG changes with STEMI?

Answer 9

Before injury
*normal EKG
Ischemia
*ST depression, peaked T waves, then T-wave inversion
Infarction
*ST elevation, and appearance of Q waves
Fibrosis
*ST segments and T waves return to normal, but Q waves persist

Question 10

What leads should you look at for an inferior MI?

Answer 10

II, III, aVF

Question 11

What are the contiguous leads?

Answer 11

Lateral: I, aVL, V5, V6
Inferior: II, II, aVF
Anterior: V1, V2 (septal), V3, V4

Question 12

If there is ST elevation in the inferior leads which leads will have ST depression?

Answer 12

I and aVL
*inferior leads reciprocate to lateral leads

Question 13

If there is ST elevation in the anterior leads which leads will have ST depression?

Answer 13

Inferior leads II, III, AVF
*Anterior leads reciprocate to inferior leads

Question 14

If there is ST elevation in the lateral leads which leads will have ST depression?

Answer 14

Inferior leads (II, III, AVF)
*lateral reciprocates to inferior leads

Question 15

What are the EKG changes during a NON-STEMI

Answer 15

Before injury
*normal EKG
Ischemia
*ST depression & T wave inversion
Infarction
*ST depression & T wave inversion
Fibrosis
*ST returns to baseline, but T-wave inversion persists

Question 16

What causes an anterior MI?

Answer 16

Occlusion of proximal left anterior descending coronary artery

Question 17

What will be shown on the EKG with an anterior MI?

Answer 17

1. Significant Q (s) waves, ST elevation and T wave inversions seen in leads
   V1, V2,

Question 18

What will prompt you to think of a posterior ischemia?

Answer 18

1. Large R wave and ST depression in V1 or V2

Question 19

If you suspect a posterior MI what can you do to confirm one?

Answer 19

1. Reverse trans illumination
2. Mirror test
   *invert and turn it backwards
   *There will be Q waves and ST elevation

Question 20

What is another name for STEMI?

Answer 20

Q-wave / transmural

Question 21

What is another name for NON-STEMI?

Answer 21

Non-q wave or subendocardial