ECGs

Question 1

Normal duration of a P wave

Answer 1

0.08 to 0.10 seconds

Question 2

Normal amplitude of a P wave

Answer 2

0.5mm to 2.5mm, rarely over 2mm

Question 3

Which leads have direct view of the SA node

Answer 3

V1 and V2

Question 4

If a negative P’ wave is present, where is the ectopic pacemaker located

Answer 4

Left atrium or in the AV junction, with retrograde conduction to the AV node

Question 5

Normal duration of a QRS complex

Answer 5

0.06 to 0.12 seconds

Question 6

Normal Q wave depth in relation to the R wave

Answer 6

Less than 25%

Question 7

Normal T wave duration

Answer 7

0.10 to 0.25 seconds

Question 8

Normal T wave amplitude

Answer 8

Less than 5mm

Question 9

Normal PR interval

Answer 9

0.12 to 0.20 seconds

Question 10

What can a prolonged PR interval represent

Answer 10

• Delayed conduction through the AV node or Bundle of His

Question 11

What can a shortened PR interval represent

Answer 11

• An ectopic pacemaker close to the AV node or AV junction

- An abnormal conduction pathway which bypasses the AV node

Question 12

Where is the QT measured

Answer 12

From the first wave of the QRS complex until the T wave returns to baseline

Question 13

When is a rhythm considered to be irregular

Answer 13

When the shortest and longest R-R intervals vary by more than 0.08 seconds (should not vary by >10%)

Question 14

What is a first-degree AV block

Answer 14

A constant delay in conduction through the AV node, characterised by abnormally prolonged PR intervals

Question 15

What is a second-degree type I (Wenckebach) block

Answer 15

A gradual lengthening of the PR interval, until a QRS complex is dropped

Question 16

What is a second-degree type II block

Answer 16

An altered AV conduction ratio, where PR intervals are equal but QRS complexes are occasionally dropped

Question 17

What is a third-degree (complete) block

Answer 17

An absence of conduction between the atria to the ventricles, resulting in no relationship between P waves and QRS complexes

Question 18

What are the characteristics of Normal Sinus Rhythm

Answer 18

Rate: 60-100
Regularity: Regular
P wave: Upright, rounded
PR Interval: 0.12 - 0.20 seconds
QRS Complex: Normal
Origin: Sinoatrial node