I am pretty scared. About one year ago I started experiencing arrythmias that were very noticeable. When they occurred I would get light-headed, and I could feel the blood almost drain from my head and sense my heart skipping beats. He told me that qualifies as mildly dilated, but he said that my systolic function was well preserved.
Viral infections can do it.
High blood pressure can do it. Deformed heart valves can do it. Certain illicit drugs and alcohol can do it. Sometimes heart dilation runs in the family, that is it is inherited. Sometimes no reason is discovered, even after extensive tests.