Can An Enlarged Heart Cause Shortness Of Breath?

I havd a shortness of breath problem when i lay on my back. On my sides isnt quiet as bad. Also when i inhale and exhale there is a flutter. I have no swelling of my feet anchles or anywhere else. This all of the sudden hit me about 3 weeks ago. I have had cat scan chest x ray. All i have been told is heart is slightly enlarged. Also when i run i feel my guts hinder my breathing when iam running