Review Question - QID 108934

A 4-year-old boy is brought in by his grandmother for worsening seizure activity. She reports that occasionally he “suddenly drops” when running around the house. She says that his first seizure occurred 1 year ago. Since then, he has been on valproic acid but the seizure activity remains unchanged. He was recently enrolled in daycare because she could no longer care for him full-time. Since then, the seizure activity has increased and the daycare facility also noted concerns over his lack of response to voice commands. Family history is significant for a cousin who died suddenly at a young age. His temperature is 98.6°F (37°C), blood pressure is 105/52 mmHg, pulse is 110/min, and respirations are 25/min. A physical exam is significant for lack of response to auditory stimulation. An EEG is performed, which is unrevealing. An ECG is shown in Figure A. The patient is then startled when a door is closed quickly and he suddenly loses consciousness. An ECG is quickly performed and is shown in Figure B. An electrolyte panel is drawn with the following findings:

Serum:
Na+: 142 mEq/L
Cl-: 88 mEq/dL
K+: 3.4 mEq/L
HCO3-: 24 mEq/L
BUN: 11 mg/dL
Glucose: 67 mg/dL
Creatinine: 0.6 mg/dL
Mg2+: 1.7 mg/dL

Which of the following is the most appropriate next step in management?