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.