EKG certification Certification EKG Heart Rate & Rhythm Analysis 1 — Questions and Answers
Question 1: When using the 6-second strip method to calculate heart rate, the number of R waves counted within the strip is multiplied by which number?
- 6
- 10 (Correct answer)
- 15
- 20
Correct answer: 10
A standard 6-second strip multiplied by 10 gives the number of beats per minute. This method is especially useful for irregular rhythms because it averages the rate over a defined time interval.
Question 2: A patient's EKG shows exactly 8 large boxes between two consecutive R waves. Using the large-box (300) method, what is the approximate heart rate?
- 38 bpm (Correct answer)
- 50 bpm
- 75 bpm
- 150 bpm
Correct answer: 38 bpm
The large-box method divides 300 by the number of large boxes between R waves. 300 ÷ 8 = approximately 37.5, rounded to 38 bpm, indicating bradycardia.
Question 3: An EKG rhythm strip shows upright, uniform P waves before every QRS complex, a PR interval of 0.16 seconds, a regular R-R interval, and a rate of 78 bpm. This rhythm is most consistent with which of the following?
- Sinus bradycardia
- Normal sinus rhythm (Correct answer)
- Accelerated junctional rhythm
- First-degree AV block
Correct answer: Normal sinus rhythm
Normal sinus rhythm has a rate of 60–100 bpm, upright and uniform P waves preceding each QRS, a PR interval of 0.12–0.20 seconds, and a regular rhythm — all criteria met here.
Question 4: A CNA notices on an EKG rhythm strip that the R-R intervals lengthen slightly during inspiration and shorten during expiration, but the P wave morphology remains normal. This finding is most consistent with which rhythm?
- Wandering atrial pacemaker
- Atrial flutter
- Sinus arrhythmia (Correct answer)
- Second-degree AV block type I
Correct answer: Sinus arrhythmia
Sinus arrhythmia is a normal variant in which the R-R interval varies with the respiratory cycle. The pacemaker remains the SA node, so P wave morphology stays normal.
Question 5: An EKG strip shows a rapid, narrow-complex rhythm at 190 bpm with no clearly identifiable P waves preceding the QRS complexes. Which rhythm does this most likely represent?
- Ventricular tachycardia
- Sinus tachycardia
- Supraventricular tachycardia (SVT) (Correct answer)
- Accelerated idioventricular rhythm
Correct answer: Supraventricular tachycardia (SVT)
SVT produces a rapid rate (often 150–250 bpm) with narrow QRS complexes because conduction through the ventricles is normal. P waves may be absent, hidden, or retrograde. Ventricular tachycardia would show wide QRS complexes.
Question 6: On a rhythm strip, the R-R interval measures 25 small boxes. Using the small-box method (1500 ÷ number of small boxes), what is the heart rate?
- 50 bpm
- 60 bpm (Correct answer)
- 75 bpm
- 100 bpm
Correct answer: 60 bpm
The small-box method divides 1500 by the number of small boxes between R waves. 1500 ÷ 25 = 60 bpm, indicating the patient is at the lower boundary of the normal range.
EKG certification Certification EKG Heart Rate & Rhythm Analysis 1
When using the 6-second strip method to calculate heart rate, the number of R waves counted within the strip is multiplied by which number?