EKG certification Certification EKG Heart Rate & Rhythm Analysis 2 — Questions and Answers
Question 1: A patient's EKG strip shows 18 large boxes between two consecutive R waves. What is the approximate heart rate?
- 83 bpm (Correct answer)
- 75 bpm
- 60 bpm
- 100 bpm
Correct answer: 83 bpm
Heart rate is calculated by dividing 300 by the number of large boxes between R-R intervals: 300 ÷ 18 ≈ 83 bpm (using interpolation between 3.6 large boxes, yielding approximately 83 bpm).
Question 2: Which method is most accurate for calculating heart rate on an EKG strip with an irregular rhythm?
- Count R waves in a 6-second strip and multiply by 10 (Correct answer)
- Divide 300 by the number of large boxes between R waves
- Divide 1500 by the number of small boxes between R waves
- Use the sequence method starting from an R wave on a dark line
Correct answer: Count R waves in a 6-second strip and multiply by 10
The 6-second method is preferred for irregular rhythms because it averages the rate over multiple beats rather than relying on a single R-R interval.
Question 3: An EKG rhythm strip shows a regular rhythm with R-R intervals of exactly 20 small boxes apart. What is the heart rate?
- 75 bpm (Correct answer)
- 60 bpm
- 100 bpm
- 150 bpm
Correct answer: 75 bpm
Dividing 1500 by the number of small boxes (1500 ÷ 20 = 75) gives a heart rate of 75 bpm.
Question 4: A rhythm is described as regularly irregular with a repeating pattern of progressively longer R-R intervals followed by a dropped beat. Which rhythm does this most likely represent?
- Second-degree AV block Type I (Wenckebach) (Correct answer)
- Second-degree AV block Type II
- Sinus arrhythmia
- Atrial flutter with variable block
Correct answer: Second-degree AV block Type I (Wenckebach)
Wenckebach (Mobitz Type I) is characterized by progressive PR prolongation and R-R shortening until a QRS is dropped, creating a regularly irregular pattern.
Question 5: On a standard 12-lead EKG, what does a narrow QRS complex (less than 0.12 seconds) indicate about the origin of the rhythm?
- The impulse originates above the ventricles (Correct answer)
- The impulse originates in the ventricles
- The impulse is conducted via an accessory pathway
- The impulse originates in the bundle of His
Correct answer: The impulse originates above the ventricles
A narrow QRS complex indicates supraventricular origin, meaning the electrical impulse travels normally through the His-Purkinje system from above the ventricles.
Question 6: When analyzing an EKG strip, you notice the R-R intervals vary with respiration — shorter during inspiration and longer during expiration. What is the most likely rhythm?
- Sinus arrhythmia (Correct answer)
- Wandering atrial pacemaker
- Multifocal atrial tachycardia
- Premature atrial contractions
Correct answer: Sinus arrhythmia
Sinus arrhythmia is a normal variant where heart rate increases with inspiration and decreases with expiration due to changes in vagal tone.
EKG certification Certification EKG Heart Rate & Rhythm Analysis 2
A patient's EKG strip shows 18 large boxes between two consecutive R waves.
What is the approximate heart rate?