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Well dear if you could have told your age and gender it would be very easy for me to narrow diagnosis. In addition you said you are hypothyroid pateint i.e your thyroid hormones are less than normal people. In that case TSH
should not be normal but higher than normal individual.
If you are really hypothyroid and taking thyroid hormones for the problem then palpation means you are taking more drugs than your need. so adjust the dose by asking your physician.
if your are not taking thyroid drugs and your thyroid levels are normal then you might have some common rhythm disorders. we call these diseases arrhythmia
in which your heart beat rate and rhythm is disturb. If you were my patient with these complain i would have done Holter Monitoring for you. which is a device which take ECH record of your whole one day.. as these arrythmias attacks are transistional so they are very hard to catch on normal ECH which just check your rythm for few seconds. Holter monitios check your ECH for whole day so its a very big chance to not your arrhythmia on it.
If Holter monitors tell you you have SVT
( a type of arrhythmia) then you will take Metoprolol
medication which will lowers heart rate
. but for permanent solution of the problem EP/RFA is recommended which is minimal invasive procedure which burns down the part of heart which is causing this arrhythmia. we do this procedure alot in our Center and its quite effective procedure.