An ablation catheter adapted for ablating a greater splanchnic nerve from within an intercostal vein, comprising: an elongate shaft having a length such that at least a portion of a linear distal section of the elongate shaft can be positioned in a T9, T10, or T11 intercostal vein; distal and proximal electrically conductive flexible and coiled ablation electrodes (132, 133) carried by the linear distal section, the distal and proximal electrically conductive flexible and coiled ablation electrodes (132, 133) together having an axial length from 5 mm - 25 mm and an axial spacing therebetween that is not more than 2.0 mm, a plurality of distal electrode irrigation ports; a plurality of proximal electrode irrigation ports; a plurality of central irrigation ports axially between the distal electrode and proximal electrode, characterized by the fact that the ablation catheter further comprises a plurality of distal irrigation ports distal to the distal electrode, the plurality of distal irrigation ports being axially aligned and equidistantly spaced circumferentially around the linear distal section, with: the plurality of distal electrode irrigation ports in a helical configuration disposed between windings in at least a central section of the distal electrode, the plurality of proximal electrode irrigation ports in a helical configuration disposed between windings in at least a central section of the proximal electrode, and the plurality of central irrigation ports axially aligned and equidistantly spaced circumferentially around the linear distal section. an elongate shaft having a length such that at least a portion of a linear distal section of the elongate shaft can be positioned in a T9, T10, or T11 intercostal vein; distal and proximal electrically conductive flexible and coiled ablation electrodes (132, 133) carried by the linear distal section, the distal and proximal electrically conductive flexible and coiled ablation electrodes (132, 133) together having an axial length from 5 mm - 25 mm and an axial spacing therebetween that is not more than 2.0 mm, a plurality of distal electrode irrigation ports; a plurality of proximal electrode irrigation ports; a plurality of central irrigation ports axially between the distal electrode and proximal electrode, characterized by the fact that the ablation catheter further comprises a plurality of distal irrigation ports distal to the distal electrode, the plurality of distal irrigation ports being axially aligned and equidistantly spaced circumferentially around the linear distal section, with: the plurality of distal electrode irrigation ports in a helical configuration disposed between windings in at least a central section of the distal electrode, the plurality of proximal electrode irrigation ports in a helical configuration disposed between windings in at least a central section of the proximal electrode, and the plurality of central irrigation ports axially aligned and equidistantly spaced circumferentially around the linear distal section. the plurality of distal electrode irrigation ports in a helical configuration disposed between windings in at least a central section of the distal electrode, the plurality of proximal electrode irrigation ports in a helical configuration disposed between windings in at least a central section of the proximal electrode, and the plurality of central irrigation ports axially aligned and equidistantly spaced circumferentially around the linear distal section.