a) End of the P wave to the end of the R wave
b) Duration is 0.2 to 0.4 seconds
c) Atrial depolarization & conduction through AV node
d) Correspond to JVP ‘a’ wave
e) Length is shortened in heart block
Answer
a.F
b.F
c.T
d.F
e.F
Discussion
a.
- PR interval – beginning of the P wave to the beginning of the QRS complex
- PR segment- end of p wave to begin of the QRS complex
- ST segment – from the end of QRS complex to the beginning of T wave
- QT interval - beginning of the QRS complex to the end of T wave
b.
- P wave – height is less than 2.5 mm and width less than 0.11 s in the lead 11
- PR interval – 0.12 to 0.2 S (3 – 5 small squares )
- Normal QRS complex- less than 0.12 S ( less than 3 smaller squares )
- Normal QT interval – 0.42 S
c.
- P wave due to atrial depolarization
d.
- a wave in JVP due to atrial systole
e.
- PR interval represents the time taken to spread of depolarization from the SA node to the AV node
- In heart block this conduction process interferes resulting prolong the PR interval