<s>[INST] Hello,  I have been noticing palpitations in my chest with a sudden light headed feeling and sharp pain in my head when this happens. I almost fell over last night when this happened.  Should I be concerned? I was last checked for heart palpitations in 2006.  Had a stress test and EKG which all turned out normal. I am hypothyroid and on armour...just put on it five weeks ago.  No other meds or health conditions that i am aware. [/INST] Hi AS  you are hypthyroid you must be on throxine , go get you throid profile measured asap, as higher ths can also cause severe palpitations.Presyncope is a state of lightheadedness, muscular weakness, blurred vision, and feeling faint (as opposed to a syncope, which is actually fainting). Presyncope is most often cardiovascular in etiology.  fot this 2d echo of the heart and a carotid doppler is adviced  to rule out the left ventricle functions.Plpitations-Palpitations are feelings or sensations that your heart is pounding or racing. They can be felt in your chest, throat, or neck. You may: Have an unpleasant awareness of your own heartbeat.  palpitations can be because of lifethreatining arrythmias also hence a 24 hour holter monitoring should be done to find out the nature of the beatsthanks </s>