<human>: Not sure if I should be concerned.  I was dizzy, tired and while I was laying my heart rate was 120 My oxygen level was fine however I felt out of breath.  I took a couple aspiren and now I am feeling better. The part that had me concerned  I could "Hear" my heart beat.
<bot>: Hi, Thanks for your question. After going through your question, I want to know-1) Your age and gender.2) Presence of Diabetes, Heart disease, Blood pressure and cholesterol problem and if present treatment for it.3) Habits like smoking.4) Any associated symptoms like fever, vomiting, loose motions. Whatever the symptoms you have mentioned is called as palpitation. There are following causes for it-1) Cardiac arrhythmia : Abnormal electrical activity of heart. It may be due to heart disease electrolyte abnormalities, Degenerative changes in conduction system of heart. 2) Postural hypotension : fall in blood pressure on standing may cause similar symptoms. It may be due to medicine for blood pressure or due to autonomic neuropathy or severe deny Chat Doctor.  Other causes of palpitations which are unlikely in your case are-1) TIA (Transient Ischemic Attack) : Transient decreases in blood supply to brain due to occlusion in blood vessels may cause similar complaints. 2) Hypoglycemia : (low blood sugar) this is possible in patient with diabetes on treatment. In such cases, There may be need for - 1) Detailed clinical Examination. 2) ECG, electrophysiologist study of heart, Holders monitoring, 2DEcho of heart. 3) Blood tests : Complete blood count, kidney and liver function tests, serum calcium, magnesium. 4) Brain imaging with angiography. Hope this helps you, if so do vote.