ECG 5: Ischemia and Infarction

Question 1

types of MI

Answer 1

1: spontaneous MI
2: MI sec to ischemic imbalance
3: MI resulting in death when biomarker values are unavailable
4a: MI related to PCI
4b: MI related to stent thrombosis
5: MI related to CABG

Question 2

ST depression and T wave changes

Answer 2

a new ST depression ≥0.05 mV (≥0.5mm) in 2 contiguous leads

T wave inersion ≥0.1 mV (≥1 mm) in 2 contiguous leads with a prominent R wave or R/S ratio >1

Question 3

ST elevation

Answer 3

≥0.1 mv (≥1 mm) in all leads (except V2-V3)

in leads V2-V3, the ff cut points apply:
≥0.2 mv (≥2 mm) in men ≥40 years
≥0.25 mV (≥2.5 mm) in men <40 years
≥0.15 mV (≥1.5 mm) in women

Question 4

remarks on Hyperacute T waves

Answer 4

occur seconds after the occlusion arises

these persist only for a few minutes

Question 5

remarks on pathologic Q waves

Answer 5

occur within 6-16 hours

generally permanent, but may occasionally normalize within a year

Question 6

anterior / anteroseptal infarct

Answer 6

V1-V4
no reciprocals
LMCA, LAD

Question 7

Septal infarct

Answer 7

V1-V2
no reciprocals
Septal branches of LAD

Question 8

Lateral infarct

Answer 8

I, aVL, V5-V6
reciprocal II, III, aVF
LCX

Question 9

Inferior infarct

Answer 9

II, III, aVF
reciprocal in I, aVL
RCA, LCX

Question 10

Posterior infarct

Answer 10

V7, V8, V9
reciprocal in V1-V3 >2 mm depression
RCA, LCX

Question 11

right ventricular infarct

Answer 11

V1, V4R
Reciprocal in I, aVL
RCA

Question 12

Posterior leads

Answer 12

V7 - left posterior axillary line
V8 - tip ofleft scapula
V9 - left of the vertebra

Question 13

myocardial infarction in unknown onset LBBB

Answer 13

SGARBOSSA CRITERIA
ST segment elevation ≥1 mm and concordant with QRS complex - 5 points
ST segment depression ≥1 mm in leads V1, V2, or V3 - 3 points
ST segment elevation ≥5 mm and discordant with QRS complex - 2 points

Score ≥3 points has 90% specificity for STEMI

Recent recommendations suggest that if ACS by history, treat as ACS regardless of meeting criteria for sgarbossa of chronic LBBB

Question 14

remarks on T wave inversions in infarction

Answer 14

Post-ischemic T-wave inversion starts before 24 hours, and persists for up to a few weeks

Question 15

DeWinter’s sign

Answer 15

Occasionally the ECG in ACS involving the occlusion of the LAD will show a paradoxical combination of ST depressions and prominent T wavese, especially in the precorial leads

Question 16

Occasionally the ECG in ACS involving the occlusion of the LAD will show a paradoxical combination of ST depressions and prominent T wavese, especially in the precordial leads

Answer 16

DeWinter’s sign