Headaches & Bradycardia

I am 64 and my pulse during the day can be as low as 51 while sitting, and while laying down (and monitored during a hospital visit for chest pain) it went down to 45.  I used to wake up with headaches - now I have them during the day.  I had a nulcear stress test and there were no detectable blockages. I do have  ST depression though it is considered not clinically significant. My blood work is very good.  Two years ago an MRI showed there was mild cerebral shrinkage.  Is all this related?  

[Jerry_NJ]

Sorry I can' offer more, but I do believe low blood carried oxygen (too low HR) can cause headaches.  I do not know if there is any long-term danger or damage that can result, but I think not.... just pain, which we all want to avoid.