Marked First-Degree Atrioventricular Block and Pseudo-Pacemaker Syndrome in a Pediatric Patient.

We describe a 17-year-old female who presented with 3 weeks of abdominal pain, exercise intolerance, and an episode of altered mental status found to have marked first-degree atrioventricular block. Exercise stress test and cardiac catheterization demonstrated pseudo-pacemaker syndrome, and a permanent pacemaker was placed. Following placement, she has resolution of symptoms and markedly improved exercise tolerance.