My mom is 73 and has high blood pressure and diabetes she has also had triple bypass surgery a few years ago. she is is the hospital now for very low ?

Low BP: There are many reasons for low BP in a cardiac patient. The heart function could be reduced, too much BP lowering medication, or fluid around the heart. There are other non-heart reasons such as an infection or problems with thyroid or adrenal gland, or also anemia. Could be as uncomplicated as dehydrated/fluid deplete status. It is good she is being evaluated in a hospital setting.