ECG

Question 1

You should always look at an ECG within the clinical context of the patient. T/F?

Answer 1

True

Question 2

Describe a systematic approach to an ECG

Answer 2

Assess if electrical activity is occuring
Assess heart rate and rhythm
Determine QRS axis
Assess P waves (presence, rhythm and morphology)
Check P-R interval
Assess width. and morphology of QRS complex
Look at ST segment
Assess morphology of T wave

Question 3

How can heart rate be determined from an ECG is there is a regular rhythm?

Answer 3

300 / number of large squares between each QRS complex

Question 4

How can heart rate be determined from an ECG is there is an irregular rhythm?

Answer 4

Number of QRS complexes present in rhythm strip x 6

Question 5

What is the normal size of the PR interval?

Answer 5

<200ms / one large square

Question 6

What is the normal width of the QRS complex?

Answer 6

<120ms or 3 small squares

Question 7

What is the normal length of the QT. interval?

Answer 7

<440ms or 11 small squares

Question 8

QRS complexes will be broad in normal sinus rhythm. T/F?

Answer 8

False - they will be narrow (<120ms)

Question 9

In complete AV block what is the relationship between P and QRS waves?

Answer 9

No relationship - P waves appear to be occurring randomly

Question 10

What is the relationship. between P and QRS wave in second degree AV block?

Answer 10

1:1 or 2 2:1

Question 11

Describe the appearance of second degree AV block on ECG

Answer 11

Normal or slow heart rate
Irregular rhythm 
Narrow QRS
P waves present
1:1 or 2:1 for P:QRS

Question 12

Describe the appearance of left bundle branch block on ECG

Answer 12

Broad QRS
Dominant S wave in V1
Dominant R wave in V6

Question 13

In what direction does the ventricle depolarise in left bundle branch block?

Answer 13

From right ventricle to left

Question 14

In what direction does the ventricle depolarise in right bundle branch block?

Answer 14

From left to right

Question 15

Describe the appearance of right bundle branch block on ECG

Answer 15

r wave and deep S in V1

q wave and tall R in V6

Question 16

P waves are absent in supraventircular tachycardia. T/F?

Answer 16

True

Question 17

What is the heart rate in supra ventricular tachycardia?

Answer 17

Fast

Question 18

What is the heart rhythm is. supra ventricular tachycardia?

Answer 18

Regular

Question 19

There are no waves so the relationship between P and QRS waves cannot be assessed in supra ventricular tachycardia. How can the. AV node be blocked in order to assess the activity of the atrium?

Answer 19

Adenosine

Question 20

What is the relationship between P and QRS waves in regular broad complex tachycardia?

Answer 20

Cannot be assessed as there are no P waves present

Question 21

What are the differential diagnoses of regular broad complex tachycardia?

Answer 21

Ventricular tachycardia
Supraventricular tachycardia with BBB
Supraventricular tachycardia conducted over. an AP
Ventricular pacing

Question 22

The normal P wave is positive in which leads?

Answer 22

Inferior leads

Question 23

The normal T wave has the opposite polarity to the QRS complex. T/F?

Answer 23

False - it has the same polarity as the QRS complex