A schооl-аge pаtient is brоught into the primаry care office and reports persistent chest discomfort during recess at school, which improves with rest. The patient’s upper extremity blood pressure is 130/85 mm Hg, and lower extremity blood pressure is 104/54 mm Hg. Brachial pulses are 3+ bilaterally, and femoral pulses are delayed and are 1+ bilaterally. Cardiac auscultation is normal. Which is the best next intervention?