Tissue engagement devices, systems, and methods

1. A method comprising:

advancing a first arm and a second arm of a tissue engagement device through a lumen, the first arm and the second arm comprising:

a first engaging member, and

a second engaging member;

engaging a pericardium of a patient with the first and second engaging members of the first and second arms, wherein both the first and second engaging members and the first and second arms cross each other at a position that is distal to an actuation member of the tissue engagement device during said engaging:

tensioning a portion of the pericardium by advancing the actuation member relative to both the first and second engaging members and the first and second arms distally beyond the position at which both the first and second engaging members and the first and second arms crossed each other during said engaging, thereby uncrossing both the first and second engaging members and the first and second arms, separating the first and second engaging members from each other while the first and second engaging members continue to engage the pericardium; and

after said tensioning, advancing an access device through the actuation member and through the tensioned portion of the pericardium to introduce the access device into a pericardial space of the patient.

2. A method comprising:

engaging a pericardium of a patient with first and second engaging members of first and second arms at two engagement positions of the pericardium, wherein both the first and second engaging members and the first and second arms cover a distal opening of an actuation member during said engaging:

moving the two engagement positions of the pericardium away from each other to tension a portion of the pericardium by moving both the first and second engaging members and the first and second arms via the actuation member, thereby uncovering the distal opening of the actuation member, while the first and second arms via the first and second engaging members-continue to engage the pericardium; and

advancing an access device through the distal opening of the actuation member and through the tensioned portion of the pericardium to introduce the access device into a pericardial space of the patient.

3. The method of claim 2 , wherein the first and second arms are connected to a tubular structure within which the actuation member is positioned.

4. The method of claim 3 , wherein the first and second arms and the tubular structure are integrally formed from a unitary piece of material.

5. The method of claim 2 , wherein said moving the first and second arms via the actuation member deforms the first and second arms.

6. The method of claim 2 , wherein both the first and second engaging members and the first and second arms cross each other at a position distal to a distal end of the actuation member during said engaging, and wherein said moving the first and second arms via the actuation member uncrosses both the first and second engaging members and the first and second arms.

7. The method of claim 6 , wherein said moving both the first and second engaging members and the first and second arms via the actuation member comprises positioning the actuation member between both the first and second engaging members and the first and second arms.

8. The method of claim 2 , wherein the actuation member comprises a first tube, and wherein the first and second arms are connected to a second tube.

9. The method of claim 8 , wherein the first tube is positioned within the second tube.

10. The method of claim 2 , wherein the tensioned portion of the pericardium is a planar region between the first and second arms.

11. The method of claim 1 , wherein the first and second arms are connected to a tubular structure within which the actuation member is positioned.

12. The method of claim 11 , wherein the first and second arms and the tubular structure are integrally formed from a unitary piece of material.

13. The method of claim 1 , wherein said advancing the actuation member relative to the first and second arms deforms the first and second arms.

14. The method of claim 1 , wherein the first and second engaging members at which the first and second arms cross each other are positioned distal to a distal end of the actuation member during said engaging, and wherein said advancing the actuation member relative to the first and second arms comprises positioning the actuation member between the the first and second engaging members.

15. The method of claim 1 , wherein the actuation member comprises a first tube, and wherein the first and second arms are connected to a second tube.

16. The method of claim 15 , wherein the first tube is positioned within the second tube.

17. The method of claim 1 , wherein the first and second arms cover a distal end of the actuation member during said engaging, and wherein said advancing the actuation member relative to the first and second arms uncovers the distal end of the actuation member to provide an access pathway for the access device.

18. The method of claim 1 , wherein the actuation member comprises a distal opening, wherein the first and second arms cover the distal opening of the actuation member during said engaging, and wherein said uncrossing the first and second arms uncovers the distal opening of the actuation member.

19. The method of claim 18 , wherein said advancing the access device through the actuation member comprises advancing the access device through the distal opening of the actuation member.

20. The method of claim 1 , wherein the tensioned portion of the pericardium is a planar region between the first and second arms.