The couplet means that a festering wound (nasoor) in the heart can open up anywhere it wants, and every direction seems to require surgical intervention.

This couplet uses the powerful metaphor of a chronic, festering wound (nasoor). The pain described is not momentary; it is deep-seated and persistent. The second line, 'everywhere there is a street of surgical instruments,' suggests that the suffering is not confined to one place. It implies that the pain is so pervasive and inescapable that even the tools meant to heal or cut are part of the surrounding environment. It speaks to an agony that is constant and overwhelming.