Percutaneous retrieval of the lattice-tip catheter entrapped in post-surgical atrioventricular valve apparatus: two case reports

Background: The novel lattice-tip catheter (Sphere-9, Medtronic) enables high-resolution mapping and the ability to switch between radiofrequency and pulsed electric field. Initial experience has shown promising results for treating complex ventricular tachycardias (VTs). However, safety data remain limited, particularly regarding catheter-valve interactions. Cases summary: We report two cases of mechanical entrapment of the lattice-tip catheter in the atrioventricular valves during VT ablation performed via a retrograde transaortic approach. In both cases, the catheter became entangled within the subvalvular apparatus-specifically, in the tricuspid valve of a patient with congenitally corrected transposition of the great arteries and in the mitral valve of a patient who had previously undergone mitral repair. Standard retrieval manoeuvres were unsuccessful, and resolution required percutaneous bailout strategies, specifically transseptal access with bioptomes or forceps. Both procedures were completed without long-term sequelae. These are the first reported cases of large-footprint catheter entrapment in the atrioventricular valve apparatus, highlighting potential mechanical risks associated with its employment in the ventricular setting. Discussion: Our experience emphasizes the importance of preferring transseptal access over retrograde access where feasible, due to its more favourable trajectory and the ability to support safer rescue techniques. Real-time imaging, particularly intracardiac echocardiography, proved essential both for navigation and complication management. While transaortic access remains a viable option, it should be approached with caution, necessitating a thorough understanding of device behaviour and a readiness to manage complications. These observations add important safety considerations for the expanded use of novel ablation platforms in patients with complex ventricular anatomy.