An apparatus for at least partially cutting a tissue layer, the apparatus including an elongated body with a distal portion, a tissue-engaging surface at the distal portion, and a knife located proximate to the tissue-engaging surface. The knife may have an active state, where in the active state, the knife has a cutting portion extending a first distance away from the tissue-engaging surface, and where the first distance corresponds to a depth of a desired cut within the tissue layer.
