Answer 7

7.  Choice B is the correct answer.  A key characteristic of atrial fibrillation is that is an irregularly irregular rhythm.  Since the impulse is coming from multiple foci in the the atria there is a wavy irregular baseline.  This can be contrasted with atrial flutter that has only one ectopic focus in the atria, the baseline is sawtooth and regular.  Sinus arrhythmia is an irregular rhythm that varies with the patients respiration.  The difference is the P waves, QRS complex, and T waves vary with the patients respirations.  Sinus block is when the SA node quits pacing activity for one complete cycle.  The P waves are the same because the SA node is functioning before and after the pause.