An atrial septostomy system (100) with an improved ablation method, comprising an atrial septostomy device (20), an ostomy device control mechanism (50) for controlling the atrial septostomy device, and a radio frequency power source. The atrial septostomy device (20) comprises a support frame (21, 21a, 21b, 21c) for expanding a hole in the atrial septum. The atrial septostomy device (20) further comprises an ablation member (23) arranged on the support frame (21, 21a, 21b, 21c). The radio frequency power source is electrically connected to the atrial septostomy device (20) via the ostomy device control mechanism (50). The ablation member (23) comprises a first electrode (231, 231a, 231b, 231c, 231d, 231f) and a second electrode (233, 233a, 233b). One of the first electrode (231, 231a, 231b, 231c, 231d, 231f) and the second electrode (233, 233a, 233b) is electrically connected to an output end of the radio frequency power source, and the other electrode is connected to a loop end of the radio frequency power source to form a current loop to receive energy from the radio frequency power source to ablate the atrial septum. The present application further relates to an atrial septostomy device (20) for use in the atrial septostomy system (100).L'invention concerne un système de septostomie auriculaire (100) à méthode d'ablation améliorée, comprenant un dispositif de septostomie auriculaire (20), un mécanisme (50) de commande de dispositif de stomie permettant de commander le dispositif de septostomie auriculaire, et une source d'énergie radiofréquence. Le dispositif de septostomie auriculaire (20) comprend un cadre de support (21, 21a, 21b, 21c) permettant de dilater un trou dans le septum auriculaire. Le dispositif de septostomie auriculaire (20) comprend en outre un élément d'ablation (23) disposé sur le cadre de support (21, 21a, 21b, 21c). La source d'énergie radiofréquence est connectée électriquement au dispositif de septostomie auriculaire (20) par l'intermédiai
