Method and apparatus for ablating target tissue adjacent pulmonary veins of a patient. The hub is connected to the base plate and the first blades are disposed on the base plate with respect to the hub as a center. A magnetized member is disposed within the fluid flow passage and is movable between a first position wherein fluid flow communication between the outlet and the inlet is blocked and a second position wherein fluid flow communication between the outlet and the inlet is open. The partition parts are formed of remaining parts of the sacrifice layer after the etching. The tissue removal member is rotatably disposed within the lumen of the elongate member.