Question

identify this rhythm

2nd degree type i heart block
3rd degree heart block
sinus rhythm with 1st degree heart block
sinus arrhythmia
2nd degree type ii heart block

Explanation:

Analyze the PR intervals

The PR interval progressively lengthens from the first beat to the fourth beat:

• Beat 1 PR: \(\approx 0.20\text{ s}\)
• Beat 2 PR: \(\approx 0.28\text{ s}\)
• Beat 3 PR: \(\approx 0.36\text{ s}\)
• Beat 4 PR: \(\approx 0.40\text{ s}\)

Identify the non-conducted beat

Following the fourth QRS complex, there is a P wave (visible on the T wave/ST segment) that is not followed by a QRS complex (a dropped beat), resulting in a pause.

Determine the rhythm classification

The progressive prolongation of the PR interval culminating in a single non-conducted P wave (dropped QRS) is the hallmark of a Second-Degree AV Block, Mobitz Type I (Wenckebach).

Answer:

• 2nd Degree Type I Heart Block (Correct answer)
• 3rd Degree Heart Block
• Sinus Rhythm with 1st degree Heart Block
• Sinus Arrhythmia
• 2nd Degree Type II Heart Block