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