Double Ventricular Pacing in a Patient with a "DDD" Universal Pacemaker

A patient with a DDD universal pacemaker presented with dyspnea. The electrocardiogram showed pacing artifacts both at the start of the QRS complex and 110 ms later. Also, 400 ms following sensed ventricular extrasystoles, there were normal single paced QHS complexes of slightly different morphology. An x-ray showed that the atrial electrode had displaced into the ventricle, and at exploration this was found to be due to late retraction of the electrode's active fixation helix. Following implantation of a new atrial lead, normal DDD pacing function was restored and the patient became asymptomatic.