Rapid, irregular contractions of the atrium appearing as jagged waves on an EKG are called?

• A. Atrial fibrillation
• B. Atrial flutter
• C. Ventricular fibrillation
• D. Sinus tachycardia

Answer: (A)

This question hinges on recognizing how atrial activity appears on an EKG and how it affects the rhythm. In atrial fibrillation the atria are firing in a disorganized, rapid manner, so there are no organized atrial contractions. On the tracing this shows up as a baseline filled with irregular, jagged deflections called fibrillatory waves, and the intervals between QRS complexes are irregular and unpredictable because the AV node conduction varies.

That combination—disorganized atrial activity with an irregularly irregular rhythm and fibrillatory waves—fits atrial fibrillation best.

By contrast, atrial flutter would present with a regular, sawtooth pattern of atrial activity and a more regular ventricular response. Ventricular fibrillation is chaotic activity with no recognizable QRS complexes at all and is a medical emergency. Sinus tachycardia would still have regular rhythm with normal P waves preceding each QRS at a faster rate.

So the rapid, irregular, jagged atrial activity described is characteristic of atrial fibrillation.