The present invention relates to an apparatus for treatment of a blood vessel of a patient body, the vessel having a lumen and a vessel wall. The apparatus comprises a catheter body having a proximal end and a distal end with an axis therebetween as well as a radially expandable member supported by the distal end of the catheter body, the expandable member having a low profile insertion configuration and a larger profile configuration. The apparatus additionally comprises a plurality of bipolar electrode pairs carried by the expandable member so that expansion of the expandable member within the lumen urges each electrode pair against the vessel wall, wherein each bipolar electrode pair has an inner edge spacing between electrodes of x mm and each electrode has a length of L mm； and an electrical energy source configured to apply a power in Watts for a time of t seconds such that: power=b*x∧2*L*t∧0.59, wherein b is a parameter in a range of 0.2 to 0.6.
