ECG RHYTHMS

Question 1

What is sinus arrhythmia?

Answer 1

When the SA node fires irregularly

Question 2

How do you recognise sinus arrhythmia?

Answer 2

Irregular rhythm — RR intervals shorten and then lengthen
Usually between 60-100 bts
Positive (upright) P waves
P wave before QRS complexes
Pr interval is 0.12-0.20 seconds
Qrs duration is 0.11 seconds or less

Question 3

What is sonoatrial block?

Answer 3

The SA nodes pacemaker cells imitate an impulse but it’s blocked as it exits the SA node.
Causes periodically absent PQRST complexes.

Question 4

How do you recognise sinoatrial block?

Answer 4

Irregular rhythm
Rate is normally normal
P waves - when present it is positive in lead 2
PR interval - when present between 0.12-0.2 seconds

Question 5

What ECG changes indicate a bifasicular block?

Answer 5

Right bundle branch block with Left axis deviation (left anterior fasicular block)
OR
RBBB with Right axis deviation (Left posterior fasicular block)