Methods for preventing tissue migration

1. A method of inhibiting tissue migration during a procedure, comprising: positioning an open area of a non-inflatable hood against or adjacent to a tissue region, where the hood expands when unconstrained to a deployed configuration which defines the open area; displacing an opaque fluid with a transparent fluid from the open area through a distal opening in the hood defined by the hood and the tissue region; engaging a portion of the tissue region within the open area via an end effector advanced through the open area and which grasps onto the portion, the end effector including a tapered section through which a lumen extends, the tapered section being tapered along its entire length, the tapered section being tapered along a longitudinal axis of the end effector and including threads extending from a surface of the tapered section in a direction orthogonal to the longitudinal axis, wherein engaging comprises screwing the tapered and threaded section of the end effector into the portion of tissue region; and piercing the tissue region while displacing the opaque fluid with the transparent fluid through the distal opening of the hood and while maintaining engagement of the portion of the tissue region such that distal movement of the tissue is inhibited.

2. The method of claim 1 wherein piercing comprises piercing into or through an atrial septum towards a left atrial chamber.

3. The method of claim 1 wherein piercing comprises inserting a needle through the tissue region until an adjacent body lumen is entered by the needle.

4. The method of claim 1 further comprising directly visualizing the engaging and piercing of the tissue region within the open area.

5. The method of claim 1 further comprising visualizing a position of the non-inflatable hood with respect to the tissue region via a plurality of radiopaque elements positioned along the non-inflatable hood prior to piercing the tissue region.

6. The method of claim 1 further comprising advancing a flexible member having a radiopaque distal end within the open area such that the radiopaque distal end contacts the tissue region prior to piercing the tissue region.

7. A method of inhibiting tissue migration during a procedure, comprising: expanding a non-inflatable hood to a deployed configuration which defines an open area, the hood including a distal edge; positioning the distal edge of the hood adjacent to a tissue region; extending a counter-traction device through the open area and into engagement with the tissue region; deploying a piercing instrument through the open area and into the tissue region while the counter-traction device maintains engagement with the tissue region such that distal movement of the tissue region is inhibited, wherein the counter-traction device includes an end effector with threads extending from a tapered surface in a direction orthogonal to a longitudinal axis of the end effector, the tapered surface being tapered along its entire length, wherein the tapered surface is tapered along the longitudinal axis, and wherein extending the counter-traction device into engagement with the tissue region includes threading the tapered surface of the end effector into the tissue region; and flushing a transparent fluid through the open area and distally beyond the distal edge of the hood while the piercing instrument is deployed into the tissue region.

8. The method of claim 7 wherein deploying the piercing instrument includes extending the piercing instrument through a side opening in the tapered surface.