Year 4middle twist
A 72-year-old man presents to the emergency department with a sudden onset of severe right leg pain over the past 3 hours. He also reports numbness and weakness in the affected limb. On examination, his right leg is cold and pale, and there’s absence of pulses below the knee. His blood pressure is 135/75 mmHg, and his pulse is 100 BPM and irregular.
What is the most appropriate initial investigation to confirm the diagnosis?