Determine the following:

Figure. No caption available.

Rhythm: _______________________________________

Rate: ___________________________________________

P waves: _______________________________________

PR interval: ____________________________________

QRS complex: __________________________________

What's your interpretation?

(Answers on next page)

Name that strip: Answers

Rhythm: Irregular

Rate: 60 beats/minute

P waves: Sinus

PR interval: 0.16 to 0.20 second

QRS complex: 0.06 to 0.08 second

Comment: ST segment depression is present

Interpretation: Sinus arrhythmia

Sinus arrhythmia is a normal physiologic phenomenon most common in children and young adults. It is caused by the changes in vagal tone that occur during the respiratory cycle. The heart rate gradually slows down with expiration and then gradually speeds up with inspiration. Sinus arrhythmia is of no clinical significance and does not require treatment unless it is associated with symptomatic bradycardia.

Sinus arrhythmia: Identifying ECG Features

Rhythm: Irregular

Rate: Normal (60 to 100 beats/minute) or slow (less than 60 beats/minute)

P waves: Normal in size, shape, and direction; positive in lead II; one P wave precedes each QRS complex

PR interval: Normal (0.12 to 0.20 second)

QRS complex: Normal (0.10 second or less)