The most common pacing mode used in patients with symptomatic bradycardia and an underlying sinus rhythm is:

C. DDD.

DISCUSSION: “Universal,” or DDD, pacing has been shown to have many benefits over other pacing modalities, including the ability to track the intrinsic sinus rate, pace the atrium and ventricle, maintain atrioventricular synchrony, and avoid the pacemaker syndrome. Recognition of these benefits has steadily increased the use of DDD pacemakers in the last decade, and at the present time DDD is the most common pacing mode.