Muga scans are standard when going through herceptin treatment. I've had 3 or 4. A substance is injected into the vein in your hand and you sit for about 20 mins to allow it to circulate. You then lie on a bed and a machine looks at the blood flow (I think) through your heart. It is actually quite pleasant-maybe that's just me but I quite enjoyed putting my feet up and watching the monitor in a nice quiet room. Some people have a wee snooze. It's also reassuring to know you are being closely monitored.
Hope that puts your mind at rest.
Which sort of heart scan, a MUGA or an ECHO? They both do the same thing but the procedures are very different. I am on Herceptin - only 3 more to go - and have had 3 ECHO scans so far, with another one due soon. They are easy. You lie on a bed whilst the cardiologist uses an ultrasound scan (a special one that measures things). Just some cold gel on your heart area and that's it. It takes about 20 minutes and you get the results there and then. (But you need to ask). Very similar to any ordinary ultrasound scan. The cardiologist looks at the monitor as he is doing it, and you can hear your heart pumping away. It looks at the heart and determines how much blood your left ventricle is pumping out, and also looks at the heart wall to see if it is thinning, and also to check all the valves are working properly. There may be other things too.
If its a MUGA scan I believe you have an injection of dye first, then have to wait an hour, then you have the scan. I haven't had one myself so can't comment further.