Method of ligating hollow anatomical structures

A catheter includes a plurality of expandable primary leads to deliver energy to a fallopian tube, a vein such as a hemorrhoid or an esophageal varix, or another hollow anatomical structure requiring ligation or occlusion. Each of the primary leads includes an electrode located at the working end of the catheter. Separation is maintained between the primary leads such that the leads can receive power of selected polarity. The primary leads are constructed to expand outwardly to place the electrodes into apposition with a hollow anatomical structure. High frequency energy can be applied from the leads to create a heating effect in the surrounding tissue of the anatomical structure. The diameter of the hollow anatomical structure is reduced by the heating effect, and the electrodes of the primary leads are moved closer to one another.