ECG 2: Systematic Reading

Question 1

7 steps of systematic ECG reading

Answer 1

1. rate
2. rhythm
3. axis
4. intervals
5. hypertrophies
6. ischema / infarction
7. miscellaneous

Question 2

rate determination

Answer 2

1500 / small squares
300 / big squares

300-150-100-75-60
50-43-38

Question 3

most important step in rhythm interpretation

Answer 3

identification of P waves

Question 4

differentials for right axis deviation

Answer 4

normal in children

RVH
COPD
Pulmonary embolism

Previous anterolateral MI
ASD/VSD
Dextrocardia

Question 5

differentials for left axis deviation

Answer 5

Past inferior MI
emphysema
hyperkalemia

Tricuspid atresia
Ostium Primum ASD

Question 6

differentials for extreme right axis deviation

Answer 6

emphysema
hyperkalema

venricular pacing
ventricular arrhythmia

Question 7

axis determination: 2 lead method

Answer 7

normal: I and aVF are both positive
LAD: I is positive, aVF is negative*
RAD: I is negative, aVF is positive
EAD: both are negative

*LAD: this should be confirmed with a negative II.
If II is positive, then it’s actually a normal axis

Question 8

How to determine left atrial enlargement

Answer 8

P wave duration ≥120 ms
Double-peaked or notched P wave

Question 9

Right atrial enlargement

Answer 9

Tall upright P wave in lead II (>2.5mm)
“Right is height.” - so mataas na P wave
opposite for left atrial enlargement, which is widened P wave

Question 10

LVH

Answer 10

SOKOLOW-LYON VOLTAGE CRITERIA
S in V1 + R in V5 or V6 >3.5 mV (35mm)
R in aVL >1.1 mV (11 mm)

CORNELL VOLTAGE CRITERIA
S in V3 + R in aVL ≥2.8 mV for men
S in V3 + R in aVL ≥2.0 mV for women

Question 11

RVH

Answer 11

Right axis deviation

R:S ratio in V1 >1.0 with R >5mm
Tall R in V1 ≥ 7mm
Small S in V1 <2mm
QR in V1

R:S ratio in V5 or V6 <1
Deep S in V5 or V6 >7mm
Small R in V5, V6 <3mm

Question 12

ST depression and T wave changes

Answer 12

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

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

Question 13

Cutoffs for ST elevation

Answer 13

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

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

Question 14

Localization of myocardial infarctionf

Answer 14

V1-V2: septal
V3-V4: anterior
I, aVL, V5-V6: lateral

I, aVL: high lateral
II, III, aVF: inferior

V7, V8, V9: posterior
V1, V4R: right ventricle