Srila Visvanatha Cakravarti Thakura remarks that when Lord Siva was offering obeisances unto Lord Visnu, Lord Visnu arose and embraced him. Therefore the word srivatsankena is used here - in SB 8.12.41

Expressions researched:
"Śrīla Viśvanātha Cakravartī Ṭhākura remarks that when Lord Śiva was offering obeisances unto Lord Viṣṇu, Lord Viṣṇu arose and embraced him. Therefore the word śrīvatsāṅkena is used here"

Srimad-Bhagavatam

SB Canto 8

Śrīla Viśvanātha Cakravartī Ṭhākura remarks that when Lord Śiva was offering obeisances unto Lord Viṣṇu, Lord Viṣṇu arose and embraced him. Therefore the word śrīvatsāṅkena is used here (SB 8.12.41). The mark of Śrīvatsa adorns the chest of Lord Viṣṇu, and therefore when Lord Viṣṇu embraced Lord Śiva while being circumambulated, the Śrīvatsa mark touched Lord Śiva's bosom.

SB 8.12.41, Translation and Purport

Śukadeva Gosvāmī said: O King, having thus been praised by the Supreme Personality, who bears the mark of Śrīvatsa on His chest, Lord Śiva circumambulated Him. Then, after taking permission from Him, Lord Śiva returned to his abode, Kailāsa, along with his associates.

Śrīla Viśvanātha Cakravartī Ṭhākura remarks that when Lord Śiva was offering obeisances unto Lord Viṣṇu, Lord Viṣṇu arose and embraced him. Therefore the word śrīvatsāṅkena is used here. The mark of Śrīvatsa adorns the chest of Lord Viṣṇu, and therefore when Lord Viṣṇu embraced Lord Śiva while being circumambulated, the Śrīvatsa mark touched Lord Śiva's bosom.