Interpreting MIs

Question 1

What constitutes a STEMI?

Answer 1

ST elevation in two or more anatomical contiguous leads. Sometimes ST depression +/or T wave inversion in other leads.
Pathological Q wave
New QRS Axis Deviation
Poor R wave progression
Conduction Block

Question 2

What happens within seconds to minutes of an ASTEMI?

Answer 2

Hyperacute T wave

Question 3

What happens within minutes to hours of an ASTEMI?

Answer 3

ST Dep. (lasts years) and ST Elev. (lasts weeks)

Question 4

What happens within hours to years of an ASTEMI?

Answer 4

T wave inversion

Question 5

What happens within hours/days to years of an ASTEMI.

Answer 5

Pathological q wave

Question 6

ST elevation in lead I is a sign of which vessel is blocked?

Answer 6

Cx (left dominant)

Question 7

ST depression in lead I is a sign of which vessel is blocked?

Answer 7

RCA (right dominant)

Question 8

If lead I is isoelectric, what do you do?

Answer 8

Look at ST elevation in leads II and III. III>II means RCA (right dominant). II>III means Cx (left dominant).

Question 9

Sgarbossa’s Criteria

Answer 9

Used to find MI in LBBB or ventricular paced rhythm. Need at least 3 points:
STE >1mm in lead with positive QRS (concordance) (5pts)
STD >1mm in V1, V2, V3 (3 pts)
STE >5mm with negative QRS (discordance)
3pts of more is 90% specificity and 36% sensitivity.

Question 10

Posterior MIs

Answer 10

Less common
V1-V3: 
Horizontal ST depression
Tall, broad R waves
Upright T waves
R/S ratio >1 in V2

Question 11

Signs of subendocardial ischemia

Answer 11

ST depression and/or T wave inversion. No ST elevation.

Question 12

Signs of transmural ischemia

Answer 12

ST elevation (hyperacute etc.), pathological q wave days later.

Question 13

EKG signs of an anterior MI

Answer 13

Left anterior descending artery (LAD) in V1-V4.

Question 14

EKG signs of a lateral MI

Answer 14

Cx artery (Left) in I, aVL, V5, and V6

Question 15

EKG signs of an inferior MI

Answer 15

RCA (Right marginal artery) in II, III, and aVF.