An ablation catheter for transvascular ablation of thoracic splanchnic nerves, particularly for ablating a greater splanchnic nerve or greater splanchnic nerve roots, comprising: an elongate shaft having a length such that a distal section of the elongate shaft is positionable in a T9, T10, or T11 intercostal vein; and an electrically conductive flexible ablation element carried by the elongate shaft distal section , wherein the electrically conductive flexible ablation element is connectable to an ablation energy source and wherein the electrically conductive flexible ablation element comprises a plurality of axially spaced ablation elements , characterized in that: the electrically conductive flexible ablation element has an axial length from 10 to 25 mm; each of the plurality of axially consecutive ablation elements forming the electrically conductive flexible ablation element has a length from 5 mm to 12 mm; the distal section is more flexible than the rest of the elongate shaft and is configured to take a radius of curvature as small as 5 mm, and angle up to 120 degrees, for flexibly traversing the bend from the azygos vein to a T9, T10, or T11 intercostal vein; the electrically conductive flexible ablation element is configured to deliver ablation energy circumferentially and/or deliver ablation energy that is radially symmetric around the ablation element , and each ablation element of the electrically conductive flexible ablation element has a coiled configuration. an elongate shaft having a length such that a distal section of the elongate shaft is positionable in a T9, T10, or T11 intercostal vein; and an electrically conductive flexible ablation element carried by the elongate shaft distal section , wherein the electrically conductive flexible ablation element is connectable to an ablation energy source and wherein the electrically conductive flexible ablation element comprises a plurality of axially spaced ablation elements , characterized in that: the electrically conductive flexible ablation element has an axial length from 10 to 25 mm; each of the plurality of axially consecutive ablation elements forming the electrically conductive flexible ablation element has a length from 5 mm to 12 mm; the distal section is more flexible than the rest of the elongate shaft and is configured to take a radius of curvature as small as 5 mm, and angle up to 120 degrees, for flexibly traversing the bend from the azygos vein to a T9, T10, or T11 intercostal vein; the electrically conductive flexible ablation element is configured to deliver ablation energy circumferentially and/or deliver ablation energy that is radially symmetric around the ablation element , and the electrically conductive flexible ablation element has an axial length from 10 to 25 mm; each of the plurality of axially consecutive ablation elements forming the electrically conductive flexible ablation element has a length from 5 mm to 12 mm; the distal section is more flexible than the rest of the elongate shaft and is configured to take a radius of curvature as small as 5 mm, and angle up to 120 degrees, for flexibly traversing the bend from the azygos vein to a T9, T10, or T11 intercostal vein; the electrically conductive flexible ablation element is configured to deliver ablation energy circumferentially and/or deliver ablation energy that is radially symmetric around the ablation element , and <EOS>