Aortic sclerosis is the thickening, stiffening or scarring of the aortic valve, and it typically results in a heart murmur, according to WebMD. Because the valve does not narrow, the murmur usually poses no danger, and a person can live years beyond the first sign of this affliction.
Aortic stenosis, a narrowing of the aortic valve, is a more serious condition, states WebMD. Because the heart must expend extra effort to pump blood throughout the body, a person with aortic stenosis may experience shortness of breath or chest pain and may need surgery to replace the valve. Untreated aortic stenosis can result in heart failure.