Here is the dialoge he gives when you turn in a kyv heart..
Vorskahn says ''Well done. For every kyv you bring down you save the life of one of my few remaining soldiers. Soon you will be hailed as a friend amongst the few dragorn that still resist the Muramites.''
This guy Wishes that you bring him Kyv hearts to show your loyalty and stuff. each heart gives you a Loyalist of Dranik Faction boost and Mata Muram hit.