ECG Interpretation

Question 1

What does a narrow QRS show?

Answer 1

sinus, atrial or junctional origin

Question 2

What does a wide QRS show?

Answer 2

ventricular origin, or supraventricular with aberrant conduction

Question 3

What is the ECG rule of fours?

Answer 3

Four Initial Features
Four Waves
Four Intervals

Question 4

FOUR INITIAL FEATURES

Answer 4

(1) History/ Clinical Picture
(2) Rate
(3) Rhythm
(4) Axis

Question 5

FOUR WAVES

Answer 5

1. P wave: Observe the P-wave morphology e.g. in particular P pulmonale or P mitrale
2. QRS: amplitude and progression
3. T wave: T wave inversion, T wave concordance or discordance with QRS and the presence of T wave flattening.
4. U waves: present?

Question 6

FOUR INTERVALS

Answer 6

1. PR interval
2. QRS width
3. ST segment
4. QT interval

Question 7

Normal PR?

Answer 7

Normally between 0.12-0.20 seconds (3-5 small squares).

Question 8

What does a prolonged PR interval show?

Answer 8

A prolonged or changing (esp lengthening) PR interval indicates heart block.

Question 9

What does a shortened PR show?

Answer 9

Shortened PR intervals can be because of WPW or LGL syndromes, or a junctional rhythm.

Question 10

What is a normal QRS interval?

Answer 10

The QRS-interval is normally less than 0.12 seconds (3 small squares).

Question 11

What does a wide QRS show?

Answer 11

A widened QRS width indicates some sort of conduction defect with the left or right bundle branches

Question 12

Normal QTc?

Answer 12

Between 0.38 and 0.44 seconds

Question 13

Describe the ECG Rule of Fours

Answer 13

Four Initial Features
Four Waves
Four Intervals

Question 14

ECG: What are the four initial features?

Answer 14

History
Rate
Rhythm
Axis

Question 15

ECG: What are the four waves?

Answer 15

P wave
QRS: amplitude and progression
T waves: T wave inversion, T wave concordance or discordance with QRS and the presence of T wave flattening.
U waves: present or not?

Question 16

ECG: What are the four intervals?

Answer 16

PR interval
QRS width
ST segment
QT interval

Question 17

What is a normal PR interval?

Answer 17

0.12-0.2s (3-5 small squares)

Question 18

What does a prolonged or changing PR indicate?

Answer 18

Heart block

Question 19

What does a shortened PR interval indicate?

Answer 19

WPW or LGL syndromes

Question 20

What is a normal QRS interval?

Answer 20

0.12s (3 small squares)

Question 21

What are you looking for with the ST segment?

Answer 21

Sloping (especially downsloping) or flattening of the ST segments

Question 22

What is a normal QT interval?

Answer 22

Normally, the QTc interval varies from 0.35 to 0.46 seconds (350-460 milliseconds).