Her last name comes from the late 80's neoclassical heavy metal guitarist, Yngwie Malmsteen.
Her first name is derived from the 16th century Hungarian countess, Elizabeth Bathory; who behaved much like Malmsteen in using young women to maintain her youth. (Though in a more gorier fashion.)
Her Middle name is derived from the middle name of Dracula's main source of inspiration: Vlad Tepes Dracul.
The name of her homeland Petsylvania is a pet related spin on Transylvania.
The crystal she uses to drain essence is a direct inspiration from the Jim Henson movie The Dark Crystal.
The name given to Dudley 'Count Dud-ula' is obviously a pun of the name 'Count Dracula.'
'Count Dud-Ula' also is loosely based off the name of the cartoon vampire duck 'Count Duckula.'
Another source of inspiration behind Lady Malmsteen and Petsylvania came from the video game series Castlevania. The plot where she removes Dudley as a threat by making him one of the castle's rulers is similar to the plot of Symphony of the Night.
Another video game series inspiration was drawn from Darkstalkers; where Lady Malmsteen's seductive charms and some of her physical attributes are similar to that of Morrigan Aensland.