Selectively expandable operative element support structure and methods of use

A medical device for ablation of tissue at a target site in an esophagus, comprising:

• an expandable member adapted for coupling to a distal portion of an elongate member and sized to be positionable and expandable in the esophagus, the expandable member comprising:
• a first partially-circumferential curvilinear portion;
• and
• a second partially-circumferential curvilinear portion, the first portion having a smaller index of expansion than the second portion, and the first portion comprising an electrode support;
• and
• a plurality of RF electrodes on the electrode support, a width of each RF electrode and a spacing between adjacent RF electrodes selected to allow depth-controlled ablation at the target site.

A method of providing therapy to tissue in a body, comprising:

• positioning a device comprising an operative element supported on a first portion of an expandable support member in proximity to a target tissue site in a body;
• expanding another portion of the expandable support member to place the operative element in an operating position adjacent to tissue at the target site;
• and
• providing therapy to the target tissue site using the operative element.

A method of providing therapy to tissue in a body, comprising:

• positioning an operative element in proximity to a target tissue site in a body, the operative element supported by an expandable support member comprising a first portion and a second portion, the first portion being adapted to have a smaller expansion index than that of the second portion, the operative element supported by the first portion;
• expanding the expandable support member until the operative element is in an effective operating position relative to the target tissue site;
• and
• providing therapy to the target tissue site using the operative element.

A method of delivering energy at a substantially constant delivery density from an ablational structure arranged on an expandable support member comprising:

• arranging the ablational structure on a first portion of an expandable support member comprising a first partially-circumferential portion and a second partially-circumferential portion, the first portion being substantially non-distensible;
• positioning the ablational structure in proximity to a target tissue site;
• expanding the expandable support member until the ablational structure is in a therapeutically effective operating position relative to the target tissue site;
• and
• delivering energy to the target tissue site using the ablational structure.

A method for treating tissue in a luminal organ, the method comprising:

• inserting an electrode deployment apparatus into the luminal organ, the electrode deployment apparatus comprising an array of electrodes arranged on a non-distensible and partially-circumferential portion of an exterior surface of an expandable support;
• expanding the expandable support to engage electrodes with a target site on a wall of the luminal organ while maintaining the electrode density of the engaged electrodes;
• and
• delivering energy from the electrodes to the target site.