What structural change occurs in the mitral and aortic valves due to rheumatic fever?

Rheumatic fever can lead to significant structural changes in the mitral and aortic valves primarily due to the inflammation and subsequent scarring it causes. Thickening of the valve leaflets is a common consequence of this process. The inflammatory response triggered by rheumatic fever causes the valves to become inflamed, leading to fibrous scarring. This scarring results in the leaflets becoming thickened and less pliable, which can subsequently affect the function of the valves.

Thickened valves can lead to stenosis (narrowing of the valve opening) or regurgitation (improper closure of the valve), both of which can have serious implications for cardiac function. Therefore, the structural change characterized by thickening of the valve leaflets is a hallmark of the impact of rheumatic fever on the heart's valvular apparatus.