The patient was a 73-year-old man who had undergone implantation of a dual-chamber pacemaker in January 2014 to treat a Mobitz II atrioventricular block. The routine follow-up studies carried out in the cardiac pacing unit revealed proper functioning of the device. During a scheduled visit in April 2015, the patient underwent an electrocardiogram, the results of which are shown in the Figure. The rhythm strip in the lower part of the tracing (lead II) indicates his spontaneous rhythm (first four QRS complexes) and the point of onset of the effect of a magnet placed over the pacemaker generator (from the fifth QRS complex on). Is the pacemaker functioning properly?
Suggest a solution to this ECG Contest at http://www.revespcardiol.org/es/electroreto/68/10 (only Spanish). The answer will be published in the next issue (November 2015). #RetoECG.