A 18-year-old female patient has experienced dizziness and headache for 1 year, accompanied by lower limb weakness and coldness. She reports easy fatigue, hyperhidrosis, and a 3 kg weight loss over the past year. BP: 170/100 mmHg (upper limbs), 150/90 mmHg (lower limbs). A vascular bruit is heard over the abdomen. The most likely diagnosis is: