ECG MI

Question 1

What is Myocardial ischemia and what portion of an ECG recognizes it?

Answer 1

Inadequate blood supply to heart for less than 20 min. Produces changes in the T wave due to impaired repolarization.

Question 2

What is Myocardial Injury and what portion of an ECG recognizes it?

Answer 2

Inadequate blood supply to heart for more than 20 min. Produces changes in the ST segment due to inability to fully polarize.

Question 3

What is Myocardial Infarction and what portion of an ECG recognizes it?

Answer 3

Occlusion that results in tissue death. Produces changes in the QRS complex due to complete inability to depolarize.

Question 4

What specific pattern would you see on an ECG with a patient experiencing Ischemia?

Answer 4

Inverted T waves and tall, peaked T waves

Question 5

What specific pattern would you see on an ECG with a patient experiencing Injury?

Answer 5

ST segment elevation

Question 6

What specific pattern would you see on an ECG with a patient experiencing Infarction?

Answer 6

Abnormal Q wave/QRS complex

Question 7

What are the exact ECG identifiers for a STEMI and on which leads would be analyzing?

Answer 7

Leads V2 - V3

1) ST segment elevation greater than 2 mm in men
2) ST segment elevation greater than 1.5 mm in women with an absence of left ventricular hypertrophy
3) ST segment elevation greater than 1 mm in 2 or more contiguous chest or limb leads

Question 8

A population of patients will not experience pain when having an MI (silent MI), this is because they have…

Answer 8

Diabetes

Question 9

What do I mean when I say a STEMI is “transmural”?

Answer 9

Transmural means that the infarction spans through the layers of tissue from the subendocardium to the epicardial surface.

Question 10

At what point on an ECG does a ST segment elevation begin?

Answer 10

The “J-point”, which is the point at the very end of the QRS wave.

Question 11

What condition can obscure an ST elevation analysis? Why?

Answer 11

Left Bundle Branch Block will obscure an ST elevation analysis because it produces a Wide QRS complex and the ST segment dips down below baseline

Question 12

What is an NSTEMI?

Answer 12

Non-ST Segment Elevation Myocardial Infarction.
ECG shows an ST segment depression and a T wave inversion.
Patient will have chest pain and ELEVATED cardiac enzymes (troponin, CKMB, etc)

Question 13

What is an NSTE ACS?

Answer 13

Non-ST segment Elevation Acute Coronary Syndrome.
ECG shows an ST segment depression and a T wave inversion
Patient will have chest pain and NORMAL cardiac enzymes (troponin, CKMB, etc)
Encompasses Unstable Angina

Question 14

What artery and leads would you use to find MI/Ischemia in the Anterior Wall of the Heart?

Answer 14

Left Anterior Descending (LAD) artery (known as the widow maker)
Leads V1 - V6

Question 15

What artery and leads would you use to find MI/Ischemia in the Inferior Wall of the Heart?

Answer 15

Right Coronary Artery (RCA)

Leads II, III, and AVF

Question 16

What artery and leads would you use to find MI/Ischemia in the Right Ventricle?

Answer 16

Right Coronary Artery (RCA)

Right V leads (V3R - V6R)

Question 17

What artery and leads would you use to find MI/Ischemia in the Lateral Wall of the Heart?

Answer 17

Circumflex Artery

Leads I, AVL, and V5 - V6 (think L in AVL as “Lateral”)

Question 18

What artery and leads would you use to find MI/Ischemia in the Posterior Wall of the Heart?

Answer 18

Posterior Descending Artery

Leads V1 - V3

Question 19

What is unique about recognizing an MI in the Posterior Wall from an ECG?

Answer 19

You will see a reciprocal pattern since we cannot put leads on the back of the heart. Leads V1 - V3 will show a prominent R wave (opposite of prominent Q wave) and a ST depression (opposite of ST elevation).