This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Vascular surgery, Subject name: Surgery
[{'content': 'A patient presented with local gigantism of the leg and increased pulsations of the lower limb veins. Most probable diagnosis is \nSelect and explain. \nA. Varicose veins, B. AV fistula, C. Buerger disease, D. Tumour', 'role': 'user'}, {'content': "Answer: B \nExplanation: The patient is having congenital AV fistula which has caused overgrowth of the leg. Aeriovenous fistula (AVF) AVF may be congenital or acquired (by the trauma of a penetrating wound, or surgically created for renal dialysis) Structural effect on veins - Veins are aerialised*, they become dilated touous and thick walled. Physiological effects of fistula - Increased pulse pressure (Increased systolic & decreased diastolic) Enhanced venous return result in Increased HR* and Increased CO*. Left ventricular enlargement and later cardiac failure may occur A congenital fistula in the young may cause overgrowth of limb*. In the leg, indolent ulcers may result* from relative ischemia below the sho circuit. Clinical signs A pulsatile swelling* A thrill on palpation* Continuous bruit on auscultation* Nicoladonis sign' or Branham sign* - Pressure on the aery proximal to fistula causes the swelling to diminish in size, a thrill or bruit to cease, the pulse rate to fall and the pulse pressure return to normal. Ref : Bailey & Love 25/e p923", 'role': 'assistant'}]