Echo has me worried

Hi I started experiencing palpitations last winter. It feels every now and then like an extra strong beat in my heart which leaves me a bit breathless. I went to the hospital with it last December as it had become quite frequent. They did an ecg and blood tests and everything seemed normal. But they made an appointment for me to get an echo and a 24 hour holter monitor for this month. Anyway I had my gall bladder removed in April and ever since I woke up from the surgery my heart rate has been extremely low usually in the 40s-50s while sitting down. They did blood tests and a contrast ct of my heart and said nothing was wrong with my heart and put it down to my thyroid and upped my eltroxin. It didn't really help my rate. Since then I am exhausted all the time and constantly feel out of breath. So i got my holter monitor on Thursday and brought it back on Friday when I was getting my echo. There were two ladies in the room, one doing the echo and one reporting on other peoples echoes. Anyway the lady doing my echo spent ages on one part of my heart. Then she said to the other lady " I think we should call the cardiologist down to do a bubble test" the other one said is there contrast flow? And she said no but it's not small. They were being very can't when I asked them what's wrong and they were reluctant to say anything to me. Eventually they said that there seems to be a hole in my heart. The other lady reporting seemed reluctant to call the doctor down and said it would take ages to do a bubble test today and when I said I don't mind waiting she said no. We will have to report on this and get back to your doctors and they will decide what they want to do and someone will ring you if they want a bubble test done but everything was normal so don't worry. But there is a hole there? I asked . Yes but your doctor will ring you. She then gave me an incident monitor to use for a week and said a doctor will ring me that day if they felt they wanted to do something else. I have to say it was really weird and a scary experience as I don't know why they were being so cagey. If it is serious? Why they would let me go if it was serious? Why they said I have a hole in my heart and then said everything normal but still there is a hole? What the hell does that even mean? No doctor has rang me yet so I don't know what that means either. Maybe it means it's not serious. But surely a hole in your heat that's "not small" would be serious enough for further investigation at least? Any help with this would be fantastic or if anyone had a similar experience? Or if anyone could even tell me what I should be looking for on the Internet? What its most likely to be ? Thanks xxxx