Sinus Rhythms

Question 1

Normal Sinus Rhythm

Answer 1

Rate: 60-100 bpm
Rhythm: Regular
P waves: Normal; 1 for each QRS complex
PR interval: 0.12-0.20 seconds
QRS interval: <0.12 seconds

Question 2

Sinus Bradycardia

Answer 2

Rate: <60 bpm
Rhythm: Regular
P waves: Normal; 1 for each QRS complex
PR interval: 0.12-0.20 seconds; lengthens as rate decreases
QRS interval: <0.12 seconds

Question 3

Sinus Tachycardia

Answer 3

Rate: >100 bpm
Rhythm: Regular
P waves: Normal; 1 for each QRS complex
PR interval: 0.12-0.20 seconds; shortens as rate increases
QRS interval: <0.12 seconds

Question 4

Sinus Pause / Arrest / Block

Answer 4

Rate: 60-100 bpm
Rhythm: Irregular due to missed PQRST beats
P waves: Regular; preceding each QRS complex when complexes are present
PR interval: 0.12-0.20 seconds; may be >0.20
QRS interval: <0.12 seconds