*qt-interval is the time from the start of q waves to the end of t waves.
*it represents the time taken for v.depolsraization&repolarazation.
*it is inversely propetoonal to the h.rate.
*abnormally prolonged qt-intrval is associated with increase risk of v.arryyhmia especially torsade de points.
*the corrected qt interval(qtc) estimates the qt-interval ay rate of 60 bpm.
*qtc is prolonged if more than440 ms. In men & if more than460 ms.in womens.
qtc is abnormally short if less than 350 ms.
CAUSES OF PROLONGED QTC INTERVAL;
*hypocalaemis. *hypocalcemia * hyponatraem.
hypomagnesaemiamyoc.ischemia
*post cardiac arrest *drugs
*congenital long qt- syndrome.