What fraction of the original area is the area of the reduced blood vessel? how might a calculation like this a biomechanical engineer working in the field? include your understanding of the cardiovascular system in your answer.

When the area of blood vessel reduced, the resistance will be increased quadratically and result in a reduction of the blood flow. The flow also becomes turbulent and might damage the nearby tissue, which was the blood vessel endothelial cells. This damage is the first step of atherosclerosis build up in the blood vessel.
Using this information, the biomechanical engineer should try to make vessel area larger to prevent damage to endothelial cells.