Suspect renal artery stenosis, since he also has htn

• Abdominal bruit + hypertension = Renal artery stenosis
• Most common causes of renal artery stenosis include atherosclerosis, fibromuscular dysplasia and polyarteritis nodosa
• Our patient has clear risk factors (middle-aged man with significant smoking history and likely other poor health behaviors) for atherosclerosis, which is the most common cause overall
• Fibromuscular dysplasia often seen in otherwise healthy young woman presenting with new hypertension or signs of poor brain perfusion
• Polyarteritis nodosa often seen with abdominal pain in a middle-aged man with hepatitis B (or risk factors for Hep B)

With the smoking history and bruit I took this question as "what is the pathophysiology of atherosclerosis". So, lipids in the arterial wall.