irregular irregular pulse

My husband since January has been going regularly each month to have his blood pressure and collestral
checked out - On his last visit beginning of June the nurse was not happy with the readings so checked with
his doctor as a result he was sent for an ECG - it revealed that he had an irregular irregular pulse
they put him on betablockers and asprin - He doesn't have any tight feelings or pain in his chest
He went on the tread mill but had to come off because his legs felt heavy but no tightness in his chest

What do you think it could be

[Momto3]

Have they suggested an echocardiogram?  An irregular pulse can be from any number of things, from benign extra beats to a more serious arrythmia.  It is very common for people to have extra beats (they feel like skipped beats) and not even know it.  Other people can feel every extra beat.

What diagnosis was your husband given?  I'd want to know why he is taking a beta blocker and an aspirin.  It's possible he has aflutter or afib and that could be the reason for the aspirin.  I would ask for a copy of the test results so you will have a better of idea of what he is being treat for.  

Does your husband exercise?  Could he have tired out on the treadmill because he is not used to that type of exercise?  Does he have a follow up appointment to discuss the test results?  Sorry for all the questions, but it seems that he wasn't given much information.