What Causes Numbness In Face,arm And Leg When Suffering From Heart Disease?

MY FATHER 81 YEARS OLD IN GENERALLY GOOD HEALTH, (A FEW CARDIAC EPISODES OF ANGINA LEADING TO CARDIAC STENTS) is very active and sharp mentally has been having episodes of weakness flushing of the face and numbness in his face arm and his leg. He has been to the ER twice, they have run cardiac tests,echo cardiograms, cat scans 2 MRIs one focusing on vasculature and the other on tissue. all the reports are showing normal outcomes. He was in the hospital today and had 2 episodes that last 45 min and they can t figure out what is wrong. Where do we go from here?