ECG Rhythm Analysis 1 — Questions and Answers
Question 1: What is the normal heart rate range for adults at rest?
- 60-100 beats per minute (Correct answer)
- 40-60 beats per minute
- 100-120 beats per minute
- 120-150 beats per minute
Correct answer: 60-100 beats per minute
Normal resting heart rate for adults is 60-100 bpm. Below 60 is bradycardia and above 100 is tachycardia.
Question 2: What defines ventricular tachycardia on an ECG?
- Wide QRS complexes at a rate greater than 100 bpm (Correct answer)
- Narrow QRS complexes with irregular rhythm
- Absent P waves with normal QRS
- Saw-tooth baseline pattern
Correct answer: Wide QRS complexes at a rate greater than 100 bpm
Ventricular tachycardia presents with wide QRS complexes (>0.12 sec) at a rate exceeding 100 bpm, originating from the ventricles rather than the normal conduction system.
Question 3: What is first-degree AV block characterized by?
- PR interval greater than 0.20 seconds with all P waves conducted (Correct answer)
- Dropped QRS complexes
- Complete dissociation of P waves and QRS
- Irregular ventricular rhythm
Correct answer: PR interval greater than 0.20 seconds with all P waves conducted
First-degree AV block shows a prolonged PR interval (>0.20 sec) but every P wave is followed by a QRS complex — conduction is delayed but not blocked.
Question 4: How do you calculate heart rate from an ECG strip using the 300 method?
- Divide 300 by the number of large boxes between two R waves (Correct answer)
- Count the number of QRS complexes in 6 seconds
- Multiply the P-P interval by 60
- Count small boxes between R waves and divide by 5
Correct answer: Divide 300 by the number of large boxes between two R waves
The 300 method divides 300 by the number of large boxes between consecutive R waves (R-R interval) to estimate heart rate quickly.
Question 5: What rhythm shows a saw-tooth pattern on the ECG?
- Atrial flutter (Correct answer)
- Atrial fibrillation
- Ventricular fibrillation
- Sinus tachycardia
Correct answer: Atrial flutter
Atrial flutter produces characteristic saw-tooth flutter waves (F waves), typically at a rate of 300 bpm, most visible in leads II, III, aVF, and V1.
Question 6: What is the treatment for pulseless ventricular fibrillation?
- Immediate defibrillation (Correct answer)
- Adenosine IV push
- Atropine IV
- Synchronized cardioversion
Correct answer: Immediate defibrillation
Pulseless ventricular fibrillation requires immediate defibrillation as the primary intervention, along with CPR and ACLS medications per protocol.
