Doctors diagnose charlie with a cardiac disorder that causes the hardening of arteries. what is this disorder where the arteries lose their elasticity?

Arteriosclerosis is described as a cardiac disorder that results in hardening of the arterial walls. This can affect elasticity, and in turn blood circulation and blood pressure. The illness is different from Atherosclerosis, as Atherosclerosis is a buildup of debris in the artery (Plaques forming from fat deposits, platelets, clotting, etc..) Many times though Arteriosclerosis and Atherosclerosis work in tandem to worsen cardiovascular health, greatly increasing chances of Aneurysms, Emboli (Traveling clots), or Thrombi (stationary clots)

In simple terms arteriosclerosis.  That's essentially when the walls of arteries start to become thick and harden, most commonly due to older age-- but it can also start to build up due to fats and cholesterol. Naturally, when something becomes hard and thick, it looses it's elasticity, so your answer would be arteriosclerosis.

They need to know because sometimes they have a symptom