Article Content

Determine the following:

Rhythm: _______________________________________

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

Rate: ___________________________________________


P waves: _______________________________________


PR interval: ____________________________________


QRS complex: __________________________________


What's your interpretation?

(Answers on next page)


Name that strip: Answers

Rhythm: Regular


Rate: 48 beats/minute


P waves: Sinus P waves present; one P wave to each QRS complex


PR interval: 0.28 second (remains constant)


QRS complex: 0.08 to 0.10 second


Interpretation: Sinus bradycardia with first-degree atrioventricular (AV) block


Comment: A U wave is present.


First-degree AV block may occur from ischemia or injury to the AV node secondary to acute myocardial infarction (MI) (usually inferior wall MI), increased parasympathetic tone, drug effects (beta-blockers, calcium channel blockers, digitalis, amiodarone), hyperkalemia, degeneration of the conduction pathways associated with aging, and unknown causes.


First-degree AV block produces no signs or symptoms and requires no treatment. Because first-degree AV block can progress to a higher degree of AV block, the cardiac rhythm should continue to be monitored until the block resolves or stabilizes. Medications causing AV block should be reviewed and discontinued as prescribed.


First-degree AV block: Identifying ECG features

Rhythm: Regular


Rate: That of the underlying sinus rhythm; both atrial and ventricular rates will be the same.


P waves: Sinus, one P wave to each QRS complex


PR interval: Consistent; prolonged (greater than 0.20 second)


QRS complex: Usually normal duration (0.10 second or less)