Final answer:
Rheumatic fever, caused by an autoimmune response to Streptococcus pyogenes, and age-related calcium build-up on the aortic valve can lead to aortic valve stenosis by causing the valves to become scarred, rigid, and calcified.
Step-by-step explanation:
Rheumatic fever and calcium build-up on the aortic valve might be considered problems that could potentially cause aortic valve stenosis. Rheumatic fever is an autoimmune response to the bacterium Streptococcus pyogenes that can lead to inflammation of the heart valves, scarring, and stiffness known as valvular disorders. Over time, these effects can result in aortic valve stenosis. Calcium build-up, or calcification, is an age-related process where the aortic valve becomes rigid and may calcify, leading to the valve losing flexibility and causing the heart to work harder, potentially developing aortic stenosis.
While chemotherapy, diabetes mellitus, and cardiac ischemia can have various impacts on cardiovascular health, they are less directly associated with aortic valve stenosis when compared to rheumatic fever and calcium build-up as a result of age-related changes.