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 (132, 133), 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 (132, 133) 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 (132, 133) 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 (132, 133), 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 (132, 133) 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 (132, 133) 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