Rhythm InterpretationQuestion 13 of 100
A monitor strip shows a sawtooth baseline with regular atrial waves at about 300 per minute and a QRS after every fourth sawtooth wave. What is this rhythm?
a.Atrial fibrillation
b.Sinus tachycardia with artifact
c.Atrial flutter with 4:1 conduction
d.Third-degree AV block
Explanation
Atrial flutter produces uniform sawtooth flutter waves, classically at 250 to 350 per minute, and the AV node blocks most of them so that only every second, third, or fourth impulse reaches the ventricles. Atrial fibrillation has a chaotic rather than uniform baseline. Sinus tachycardia has discrete P waves, and third-degree block shows normal P waves that are completely unrelated to the QRS complexes.
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