Restenosis or neointimal formation may occur following angioplasty or other trauma to an artery such as by-pass surgery. This presents a major clinical problem which narrows the artery. The invention provides a balloon catheter with a particular electrode configuration. Also provided is a method whereby vascular cells in the area of the artery subjected to the trauma are subjected to irreversible electroporation which is a non-thermal, non-pharmaceutical method of applying electrical pulses to the cells so that substantially all of the cells in the area are ablated while leaving the structure of the vessel in place and substantially unharmed due to the non-thermal nature of the procedure.