Heart-shaped shields were mostly used in representations of the coats of arms of royalty. Following the union between Poland and Lithuania, and the creation of the elective monarchy, it became customary to place the coats of Poland and Lithuania diagonally, with the coat of arms of the specific monarch placed centrally on top. Research continues to find out what a "heart-shaped" shield is. Most likely, the coat of Poland was placed on the left-right diagonal (I & IV) and Lithuania on the right-left diagonal (II & III) as evidenced in the shield at the top of this page. The specific monarch crest then being placed in the "heart" position.T. Pietras, Z orłem białym przez wieki. Z dziejów polskiej symboliki państwowej, Uniwersytet Łódzki, 2013.
