MRCP2-4227
A 75-year-old woman is referred to the Medical Clinic by her GP due to experiencing shortness of breath. She has been seeing her GP for the past few months regarding increasing shortness of breath during exercise. Despite some investigations, her GP has been unable to determine the cause of her symptoms. She has also been experiencing a dry cough on and off for the past 4 months. During examination, her blood pressure is 135/80 mmHg, pulse is regular at 70 bpm, and her jugular venous pulse is not raised. Although her breathing is noisy, her chest is clear on auscultation. Which investigation would be most useful in identifying the location of any obstruction?