What to look for on ECG...

Question 1

Axis Deviation

Answer 1

Leads I and AVF

Normal = both up
Left axis deviation = I +, AVF -
Right axis deviation = I -, AVF +
Extreme right = both down

Question 2

Best place to find P waves

Answer 2

Lead II

Question 3

Where to look for Atrial Enlargement

Answer 3

Lead II and V1 (biphasic is normal)

Question 4

Right atrial enlargement

Answer 4

Lead II

• Taller (increased amplitude > 2.5mm)
• Normal width
• *look for large amplitude in II, III, AVF in case right access deviation pushed P wave towards III and AVF

Lead V1
- Normally biphasic, but the upwards part will be bigger

Question 5

Left atrial enlargement

Answer 5

Longer P wave >1 small block (0.04 sec)

Lead V1
- Normally biphasic, downward part should be bigger (>1mm down)

Question 6

Right Ventricular Hypertrophy

Answer 6

Right axis deviation

V1 - R wave > S wave
V6 - S wave > R wave

Question 7

Left Ventricular Hypertrophy

Answer 7

**Voltage criteria (not useful if age <35):
S wave in V1 or V2 +
R wave in V5 or V6
> 35mm (7 boxes)

OR

V5 R-wave > 26mm (5 boxes)

OR

aVL R-wave > 11mm

• *Secondary depolarization abnormalities:
• asymmetric T-wave inversion
• downloading ST depression

Question 8

1st Degree AV block

Answer 8

PR interval > 0.2 sec

Question 9

2nd Degree AV block (both types)

Answer 9

Mobitz type 1 (Wenckebach)

• PR gets longer
• drop beat (usually every 3rd, 4th)

Mobitz type 2

• normal PR length
• random drop QRS
• ratio of drop beats varies (2:1, 3:2)

Question 10

3rd Degree AV block

Answer 10

Complete AV dissociation

Question 11

Assessing Rhythm: 4 questions to ask

Answer 11

1. normal P waves?
2. QRS narrow or wide?
3. relationship between P and QRS (i.e. AV dissociation?)
4. regular or irregular?

Question 12

AVNRT Characteristics

Answer 12

Rate: 150-250
Rhythm: regular
Retrograde P waves in II, III
V1 = R’ (P wave buried in QRS)

Question 13

Atrial Flutter Characteristics

Answer 13

Rate: 250-350

Lead II - positive deflection vs. negative deflection (more common, counterclockwise)

Question 14

MAT Characteristics

Answer 14

Rate: 100-200
P wave morphology: 2-3 beats of same P wave before it moves on, must have 3+ different P waves
Note: common with severe lung disease

Question 15

When are PVC’s concerning?

Answer 15

1. 3+ in a row
2. Multiform (coming from different places)
3. PVC falling on the T wave of previous beat
4. Any PVC in setting of MI

Question 16

Causes of Polymorphic VT (3+ PVC)

Answer 16

1. Acute MI
2. Infarction
3. Profound electrolyte imbalance
4. QT prolongation

Question 17

What is Aberrancy?

Answer 17

Premature atrial impulse, before one of the Purkinje fibres has depolarized… looks like a PVC (although there will be a P wave!)