The current invention concerns a catheterization system For performing an Interventional ablation procedure comprising: a flexible guiding catheter comprising a distal end for Insertion and a proximal end for manipulation, the distal end of the guiding catheter transformable from a substantially elongated shape for passage within the vasculature into a contact shape for contacting internal tissue along a continuous band, the flexible guiding catheter comprising a guiding Iumen, and a flexible ablation catheter comprising an ablation tip near a distal end, the ablation catheter Insertable or inserted into the guiding lumen of the guiding catheter, characterized In that the guiding catheter comprises a continuous slit at or near the distal end of the guiding catheter, said silt arranged such that, when the distal end of the guiding catheter is in said contact shape and contacts internal tissue along a continuous band, the silt defines a functional opening between the guiding Iumen and the internal tissue along said continuous band, through which slit said ablation tip is capable of ablating said internal tissue along said continuous band. The Invention further concerns a guiding catheter and an interventional ablation procedure.
