Review Question - QID 108873

A 44-year-old male presents to his primary care physician for a normal check-up. He reports that he feels well and has no complaints other than a few instances of lightheadedness over the past two months. His past medical history is notable for hypertension for which he takes metoprolol and nifedipine. His temperature is 99°F (37.2°C), blood pressure is 130/80 mmHg, pulse is 80/min, and respirations are 18/min. Physical examination reveals no significant findings. An telemetry strip of this patient is shown in Figure A. Where is the most likely defect in this patient’s conduction system?