My vet just told me that my 10 year old Dachsund has an enlarged heart?

For a couple of weeks my dog had this cough. It came about maybe 2 or 3 times a day. So we finally took her to the vet today and got an x-ray done. It turns out she has an enlarged heart and could lead to congestive heart failure. The vet gave us tussigon and and aminophylline to give to our dog. Will this help her coughing and condition? There's nothing else wrong with her. She eat's normal, does her daily routine, still plays a lot, drinks normal, not even a gray hair on her, other than this she's quite healthy. I'm such a nervous wreck now because the doctor made it sound like she could pass away any minute. I hope she lives a long life, she's such a sweetheart. Will these meds help her?