I would check out the possibility of sleep apnea. Your waking up with a start is a sign that you may be stopping breathing. Right heart enlargement can be a sign of sleep apnea - if you get your sleep apnea treated (if you do have it) - your heart size will return to normal.
Thank you for your feedback!
pdberger,
thanks for the post.
It sounds like your heart was checked into. Certainly, a normal stress and echo would be somewhat reassuring to me as a cardiologist and steer me away from the heart as a cause of your symptoms.
It sounds like you are making great progress with your exercise program. I would continue to work with your physician on that path.
Anxiety can certainly play a big factor in our health. If these issues are detrimental to your overall health they should be treated.
good luck