Question

identify this rhythm

normal sinus
sinus rhythm with 1st degree block
sinus tachycardia with 2nd degree block
sinus bradycardia

Explanation:

Analyze the heart rate and rhythm regularity

$$ \text{R-R intervals} \approx 4.5 \text{ large boxes} \implies \text{Heart Rate} \approx \frac{300}{4.5} \approx 67 \text{ bpm (regular)} $$

Evaluate P waves and PR interval

$$ \text{PR interval} \approx 7.5 \text{ small boxes} \times 0.04 \text{ s} = 0.30 \text{ s} > 0.20 \text{ s} $$

Determine the cardiac rhythm

$$ \text{Regular rhythm} + \text{Normal rate} + \text{Constant, prolonged PR interval} \implies \text{Sinus rhythm with 1st degree block} $$

Answer:

• Normal Sinus
• Sinus rhythm with 1st degree block (Correct answer)
• Sinus Tachycardia with 2nd degree block
• Sinus Bradycardia