Orthostatic hypotension

A 30-year-old man comes to the emergency department because of a near syncopal episode at work. He says that he has never had such an experience before. He describes the episode as characterized by a feeling of warmth, thirst, dizziness, and weakness that was relieved by resting. There was no chest pain, shortness of breath, or palpitations. He has no known drug allergies. His vitals are normal, but he does exhibit orthostatic hypotension. Cardiac examination shows a clear S1 and splitting of S2 on inspiration with no murmurs, rubs, or gallops. The splitting is especially prominent at the left parasternal border. Electrocardiogram shows no abnormalities. Which of the following is the most appropriate next step in management?