In an embodiment a sheath allows one to simultaneously ablate tissue, using a catheter located in the sheath, and remove fluid from a patients pericardial space, via the same sheath, all without withdrawing the ablation catheter from the sheath. Applying pressure (positive or negative) to fenestrations in the sheath may allow one to withdraw fluid from the space, navigate the sheath within the space, and/or adhere the sheath to tissue in the space. Other embodiments are described herein.
