PTT
PTT measures contact activation of the intrinsic coagulation
system by a foreign material ( e.g. device)
PTT reagent consists of lyophilized rabbit brain cephalin which supplies
the phospholipid required for plasma coagulation by way of the intrinsic pathway.
Test priciple:
PTT reagent is added to a standard plasma together with the tested device material.
Following the addition of Calcium the time is recorded until the formation of a clot.
Normally, when the device material is not causing activation of the coagulation cascade
the clotting time is very long ( 2-5 minutes at 370C) Contact activation will shorten the time.