Discussion:
Patients with an ASD are at high risk of developing AF which remains considerable even after ASD closure3, mostly due to structural atrial remodeling generating a favorable substrate for macroreentry.4,5 Clinical evidence supports that long-standing volume overload, pulmonary hypertension, and prolonged atrial stretch significantly increase the risk of AF in patients with ASD. Catheter ablation has emerged as an effective treatment strategy for these patients, especially in those with drug-refractory and symptomatic AF. The ability to perform a targeted transseptal puncture is vital to the successful outcome of such a procedure, which may thereby influence therapeutic options.
Neo-endothelialization and fibrous incorporation of the ASD closure device are generally completed within 1 to 3 months, and as described in a swine model,6 100% of the ASDs are generally closed at 3 months, even though the atrial fibrosis aggravates with the passage of time. Our patient with a history of percutaneous ASD occluder of 34-mm diameter which was implanted 16 years creates a great challenge for access to the LA in the ablation. Many different studies (Santangeliet al.7 , Li et al.8 , and Sang et al.9 ) have demonstrated the feasibility, safety, and efficacy of catheter ablation in such patients. In these studies, the TSP through the native septum was mostly performed, while some patients underwent direct puncture of the atrial septal occluder. Of note, different strategies were used to achieve left atrial access into the left atrium through the septal occlude. Santangeli et al.7 reported on the technical feasibility of direct access through the device using an upsized dilator for AF ablation under intracardiac echocardiography (ICE) guidance. Liet al. 8and Sang et al.9advanced an angioplasty guidewire in the left superior pulmonary vein. After the withdrawal of the 8 Fr dilator, they performed the sequential dilatations using a 2.5-5.0 mm non-compliant balloon under the pressure of 12-18 atm to ease sheath manipulation. The median time from ASD closure to catheter ablation in the above cohorts was 46 (6-82), 16 (6-36), and 11 (6-72) months respectively. Consideration of the fibrotic and thickened occluder in our patient, we adopted the strategy of direct access through the occluder suggested by prior studies on AF ablation in patients with an ASD.
In this case study, we encountered two major operative considerations as follows: (1) With the help of ICE, we could visualize the landmarks of atrial septal anatomy to puncture accurately without any complications; (2) Dilatation at a site across the device using appropriate peripheral balloon could create just enough transseptal opening to allow subsequent passage of the 8.5F sheath. Finally, we could open up the blocked passage to the LA, and the AF was successfully ablated.