Which condition is characterized by a "monophasic" action potential on an electrophysiological study?

• A. Atrial fibrillation
• B. Ventricular fibrillation
• C. Sinus tachycardia
• D. Premature ventricular contraction

Answer: (A)

The condition characterized by a "monophasic" action potential on an electrophysiological study is indeed atrial fibrillation. In this condition, the heart's electrical signals become chaotic, leading to irregular and ineffective contractions of the atria. The term "monophasic" refers to a single, unidirectional action potential waveform that can be seen in the atrial tissue during the disorganized electrical activity of atrial fibrillation.

During atrial fibrillation, the normal rhythm of the heart is disrupted, and the distinct monophasic action potential reflects the absence of organized atrial depolarization. Other conditions listed, such as ventricular fibrillation, sinus tachycardia, or premature ventricular contractions, display different electrophysiological characteristics, such as multiple phases or more organized activity, rather than the singular waveform characteristic of atrial fibrillation.

In summary, the unique presentation of a monophasic action potential is indicative of the irregular electrical activity found in atrial fibrillation, distinguishing it from the other cardiac conditions in terms of electrophysiological findings.