original_query: What is the pathophysiology of angioedema?
query: What is the pathophysiology of angioedema?
answer: Angioedema's pathophysiology involves bradykinin, a potent vasodilator increasing vascular permeability and causing fluid accumulation, especially noticeable in the face.  Various mechanisms interfering with bradykinin production or degradation can lead to it. In hereditary angioedema, continuous complement system activation due to C1-esterase inhibitor deficiency causes bradykinin formation and kallikrein production.  ACE inhibitors also contribute by blocking bradykinin degradation.