Shortness of Breath, Pallor in a 41-Year-Old Man: Next Steps?

A 41-year-old man presents with shortness of breath and weakness after a near syncopal episode earlier in the day. He appears pale and mildly dyspneic. He denies chest pain, cough, or fever. He has no cardiac risk factors and denies any significant past medical or surgical history. He takes no medications, has no known allergies and denies the use of tobacco, alcohol, or recreational drugs.

Vital Signs:

Temp: 98.1°F (36.7°C)
HR: Initially 168 beats/min when ambulatory, dropping to 126 after 10 minutes of rest, but suddenly increases to 154 upon standing
RR: 30 breaths/min when ambulatory, 22 at rest
BP: 108/76 mm Hg supine, but drops to 86/60 upon standing
0₂ Sat: 98% on room air

Physical examination:

Cardiopulmonary: clear lungs and a normal cardiac examination without murmurs
Abdominal: soft, non-tender and non-distended
Skin: pale and dry with conjunctival pallor

Questions

1. What else should you look for?

2. What should be included in your differential diagnosis?

3. What is your next step?

Click here for answers and discussion.