Due to repeated flow of blood across the aortic valve, calcification of the valve can occur. The calcification of the aortic valve is an age-related process. It usually causes symptoms in 8th or 9th decade of life. Reference: https://www.mayoclinic.org/diseases-conditions/aortic-stenosis/symptoms-causes/syc-20353139#:~:text=As%20blood%20repeatedly%20flows%20over,until%20ages%2070%20or%2080. Image via: https://www.researchgate.net/figure/Aortic-Valve-calcification_fig1_8419625