FCPS part 1 Medicine solved mcqs with explanation Q13

Q13: ECG of a patient shows progressively increasing PR intervals followed by dropped beat. What is the condition?

a) Third degree heart block

b) Mobitz Type 1

c) Sinus arrhythmia

d) Mobitz Type 2

Correct Answer: b

Explanation:

Heart blocks are of three types:

1. First degree heart block: PR interval prolonged (>200 ms)
2. Second degree heart block:

• Mobitz Type 1: Progressive lengthening of the PR interval until a beat is dropped (a P wave not followed by a QRS complex).
• Mobitz Type 2: Dropped beats that are not preceded by a change in the length of the PR interval

     3. Third degree heart block: The atria & ventricles beat independently of each other.