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Determine the following:

Figure. No caption a... - Click to enlarge in new windowFigure. 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)