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Chapter 9. Arrhythmias

Student Questions

Which one of the following ECG intervals or durations most closely represents the time of ventricular repolarization?

A. PR interval

B. QRS complex

C. QT interval

D. T wave

Answer: C

Option A: Incorrect. The PR interval represents time of impulse conduction through the AV node.

Option B: Incorrect. The QRS complex represents time of ventricular depolarization.

Option C: Correct. The QT interval represents the time of the entire period of ventricular repolarization.

Option D: Incorrect. The T wave represents phase 3 repolarization time, but not the time of the entire period of ventricular repolarization.

Which of the following definitions most accurately describes persistent atrial fibrillation?

A. A continuous episode of atrial fibrillation that does not terminate spontaneously and may last longer than 7 days

B. Continuous atrial fibrillation longer than 12 months in duration

C. Intermittent episodes of atrial fibrillation that start suddenly, last minutes to hours, and stop suddenly

D. The patient and clinician have jointly decided to terminate further attempts to restore/maintain sinus rhythm

Answer: A

Option A: Correct. Persistent atrial fibrillation (AF) is defined as a continuous episode of AF that does not terminate spontaneously and may last longer than 7 days.

Option B: Incorrect. Continuous AF longer than 12 months duration is defined as long-standing persistent AF.

Option C: Incorrect. Intermittent episodes of AF that start suddenly, last minutes to hours, and stop suddenly is defined as paroxysmal AF.

Option D: Incorrect. The situation in which the patient and clinician have jointly decided to terminate further attempts to restore/maintain sinus rhythm is classified as permanent AF.

Which one of the following most accurately describes the mechanism of atrial fibrillation?

A. Increased automaticity in the atria, triggering a single atrial reentrant circuit

B. Increased automaticity in the atria, triggering multiple simultaneous atrial reentrant circuits

C. Increased automaticity in the pulmonary veins, triggering a single atrial reentrant circuit

D. Increased automaticity in the pulmonary veins, triggering multiple simultaneous atrial reentrant circuits

Answer: D

Option A: Incorrect.

Option B: Incorrect.

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