Apparatus and methods are described, including apparatus for puncturing a fossa ovalis of a heart. The apparatus comprises a catheter shaped to define a catheter lumen. A puncturing element is slidably disposed within the catheter lumen, and is configured to be deployed from a distal portion of the catheter and to puncture the fossa ovalis. One or more flexible longitudinal members are configured to be deployed from the distal portion of the catheter, and upon being deployed, facilitate the puncturing of the fossa ovalis by the puncturing element, by contacting tissue at a perimeter of the fossa ovalis. Other applications are also described.
