What are the causes/symptoms/dangers of an enlarged infant heart?

My11 month old daughter who has allergy induced asthma but very rarely needs breathing treatments was having cough attacks, runny nose, fever, trouble breathing, wheezing, etc so when she wasn't getting better i took her to the ER last night.. They examined her and took x rays of her chest.. After being there for 4 hours and having to repeat the x rays twice the doctor told me that they didn't find pneumonia they found an enlarged heart.. They didnt believe it had anything to do with her bronchitis but felt we were lucky to find it this way.. She is nearly 1 yr old, 27lbs(she's a chubby girl), walking since 9 months, very active, and has never shown signs of anything serious. Her blood pressure at the ER while holding completely still was 144/99.. I'm very worried and am unable to contact her doctor till Monday. Can anyone give me any information? Also, they perscribed her antibiotics, atrovent for her breathing machine, a steroid, an anti inflamatory, and Lortab.. I don't understand the need for all of these meds especially a narcodic in an infant. Please help.