An intermittently paced rhythm: Deciphering the etiology of depolarization

We present a case of an intermittently paced rhythm in a patient with prior placement of a St. Jude Medical (SJM) dual chamber pacemaker (PPM). The patient had a history of difficult-to-control hypertension, insulin-dependent diabetes mellitus, gastroparesis and end-stage renal disease receiving hemodialysis presenting for admission due to hypertensive urgency. Initial electrocardiogram upon arrival showed sinus tachycardia, however, a follow up electrocardiogram was notable for ventricular pacing only every other beat with a shortened atrioventricular delay beyond the programmed settings of the PPM.