Have Hardening Of Arteries And Several Stents That Appear To

Have hardening of arteries and several stents that appear to have closed. I'm 81 this month. My cardiologist is out of town. I am also on blood thinners. I have not been able to walk very far for several months even tho I use an oxygen machine. Today, I am unable to stand longer than a few minutes with out a verv severe headache that becomes nearly unbearable if I continue to stand. It subsides when I am sitting or lying down. What would you suggest? Thant You, Dick Michae