Dual-Chamber Pacemaker After Sinus Node Dysfunction and Enlarged Right Atrium

ECG CHALLENGEA 57-year-old man was diagnosed in childhood with a congenital ventricular septal defect that was surgically repaired with a patch.However, a residual left-to-right shunt was left, and the patient developed severe pulmonary hypertension and severe dilatation of chambers on the right side of the heart.Because of an aortic root aneurysm with severe aortic regurgitation, he was again submitted to cardiac surgery at the age of 41 for ascending aorta and aortic valve replacement.Now, he was referred to our hospital for an electrophysiological study because of recurrent atrial flutter with an elevated heart rate causing heart failure.ECG at baseline showed sinus bradycardia and a right bundle-branch block.During the electrophysiological study, an incisional macroreentrant atrial tachycardia was induced, and the circuit was delimited at the upper lateral side of the right atrium.The atrial tachycardia was successfully ablated by applying radiofrequency at the circuit isthmus.During the electrophysiological study, the patient was diagnosed with severe sinus node dysfunction and a dual-chamber pacemaker was implanted.When he returned to the ward, an ECG was obtained (Figure 1).The nurse watches the ECG record and immediately asks you to check it.What is your interpretation?Please turn the page to read the diagnosis. Dual-Chamber Pacemaker After Sinus Node Dysfunction and Enlarged Right AtriumIs It What It Seems? CASES AND TRACESFigure 1.ECG after pacemaker implantation.Downloaded from http://ahajournals.org by on August 17,