Lecture 7- Ischemia and MI

Question 1

Define Ischemia and what does the EKG look like?

Answer 1

Decreased perfusion to the myocardium, supply demand mismatch, NO injury has occurred.

• Area of ischemia is more negative than surrounding normal tissue
• Causes ST depression
• Causes repolarization to occur along abnormal pathway
• T wave is flipped

Question 2

Define Injury and what does the EKG look like?

Answer 2

Prolonged ischemia > injury. Oxygen deprivation of the tissue will lead to the injury resulting in abnormal conduction pathways as will be evident on the EKG.

• Zone of injury does not repolarize completely
• Remains more positive than surrounding tissue, leading to ST elevation
• T remains flipped (abnormal repolarization paths along injured/ischemic areas of myocardium)

Question 3

Define Infarction

Answer 3

Injured area becomes infarction (dead tissue) if reperfusion does not occur in a timely fashion
Time is muscle idea comes from this
Dead tissue will eventually become scar tissue or electrically neutral tissue
Q wave development
-Does NOT generate any action potentials; electrically neutral
-Acts like electrical “window” in wall of myocardium
-An electrode can look through and see opposite wall.
-Unopposed, positive vector produces Q wave.

Question 4

EKG progression in infarct?

Answer 4

ECG pattern in AMI = continuum that extends from normal to full infarct.
First: T wave flips in early ischemia.
Then: ST elevation either flat or tombstoning (flipped T wave may disappear).
Finally: We see Q waves

Question 5

Define Reciprocal Changes?

Answer 5

Refers to “mirror image” that occurs when two electrodes view same AMI from opposite angles
*i would give an example but i dont understand this so…google it.

Question 6

Infarct regions: lateral?

Answer 6

I, aVL, V5, V6

Question 7

Infarct regions: inferior?

Answer 7

II, III, aVF

Question 8

Infarct regions: septal?

Answer 8

V1 and V2

Question 9

Infarct regions: anterior?

Answer 9

V3 and V4

Question 10

Infarct regions: lateral?

Answer 10

I, aVL, V5, V6

Question 11

Which infarct is known as the “widowmaker*”

Answer 11

Proximal LAD* (perfuses anterioseptal lateral region of heart)

Question 12

Infarct regions: septal?

Answer 12

V1 and V2

Question 13

Posterior Wall MI?

Answer 13

= Carousel Pony* = Bad news
To diagnose:
Understand concept of reciprocal leads.
See reciprocal changes in V1 and V2.
Almost mirror image of direct changes of AMI on complex.
You will see:
 Tall and fat R wave
 ST depression
 Upright T wave in leads V1 and V2

Question 14

Facts about infarct regions in combination

Answer 14

Usually involved multiple areas, ** There can always be differences caused by factors such as underlying pathology, dominant arterial systems, and presence of collateral blood flow. **

Question 15

Which infarct is known as the “widowmaker”

Answer 15

Proximal LAD* (perfuses anterioseptal lateral region of heart)

Question 16

Additional EKG leads?

Answer 16

-Posterior leads V7 to V10 are helpful in diagnosing posterior wall AMIs
-Right-sided leads aid in diagnosis of right ventricular infarction.
-Direct changes occurring in right ventricle are clearly seen in V4R, V5R, and V6R.
.

Question 17

Posterior Wall MI?

Answer 17

= Carousel Pony = Bad news
To diagnose:
Understand concept of reciprocal leads.
See reciprocal changes in V1 and V2.
Almost mirror image of direct changes of AMI on complex.
You will see:
 Tall and fat R wave
 ST depression
 Upright T wave in leads V1 and V2

Question 18

Q waves?

Answer 18

Noting pathologic Q waves in a regional pattern is indicative of prior MI

Question 19

New LBBB in a patient with symptoms of ischemia is considered MI equivalent**

Answer 19

Important

Question 20

REVIEW EKG examples at the end of lecture

Answer 20

GO! :D