What is a symptom of atrial fibrillation?

Atrial fibrillation is characterized by an irregular and often rapid heart rhythm due to chaotic electrical signals in the atria. This chaotic activity leads to a quivering or fluttering state of the atria, which is the direct result of erratic electrical impulses causing them to contract in an uncoordinated manner. As a result, option B accurately describes one of the hallmark symptoms of atrial fibrillation.

In contrast, the other choices depict characteristics that are not observed in this condition. Regular atrial contractions would indicate a stable rhythm, typical of a normal sinus rhythm, which does not occur in atrial fibrillation. Sustained sinus rhythm refers to a normal heart rhythm originating from the sinus node, which is disrupted in atrial fibrillation. Normal QRS waves are indicative of normal ventricular function and rhythmic atrial activity, which is also not the case in atrial fibrillation, as the irregularity leads to varying QRS complexes. These distinctions help to emphasize the correct identification of symptoms associated with atrial fibrillation.