Conversation: The conversation between human and AI assistant.
[|Human|] During my 4mph walk on my treadmill after 50 minutes as I was going into my cool down I felt fluttering in my chest then a pounding with no pain but lightheadedness then rapid heartbeat. Lasted about 1 to 2 minutes My last stress test in Feb of this year was normal & so was my echo cardiagram I have be using a treadmill for at least 20 years. I do have a lot of silent mild belching & much flatulance
[|AI|]  Thanks for your question on ChatDoctor.in my opinion you are having nothing but palpitation. Fluttering dealing in chest is most commonly seen in palpitation. And after 50 minutes of treadmealeven normal person can have high heart rate. But worrisome symptom in your description is lightheadedness. These demands repeat stress test and stress echocardiography. As possibility of decrease blood supply to brain in stress which causes lightheadedness. So consult cardiologist and discuss all these.