Objectives: We sought to determine the incidence, nature, and predisposing factors of atrioventricular block (AVB) associated with closure of atrial septal defects (ASDs) using the Amplatzer septal occluder (ASO).
Background: In our institution, 162 patients underwent ASD closure using ASO between December 1997 and December 2001. This includes small children with large defects.
Methods: Electrocardiographic tracings during ASO implantation and at follow-up visits were reviewed. Anatomic characteristics and device size were assessed as potential risk factors for AVB.
Results: Ten patients (6.2%) presented with new-onset (n = 9) or aggravation of preexisting (n = 1) AVB. Atrioventricular block occurred during the procedure (n = 3) or was first noted one day to one week later (n = 7). Patients had first-degree (n = 4), second-degree Wenckebach (n = 4), or third-degree (n = 2) AVB, with no symptoms or hemodynamic compromise. First-degree AVB persisted in two patients at 12 and 33 months of follow-up, whereas most recovered normal AV conduction within one (n = 7) or six months (n = 1). A larger shunt (Qp/Qs ratio 2.8 +/- 0.9 vs. 2.1 +/- 0.8, p < 0.01) and device size (24 +/- 5 vs. 19 +/- 6 mm, p < 0.01) were the only determinant factors for AVB. A device size > or =19 mm was used in 90% (9 of 10) of patients who developed AVB, as compared with 49% of those without AVB (p < 0.02).
Conclusions: Closure of ASDs using the large ASO can be associated with the development of AV block and mandate a closer follow-up. In our series, however, all AVBs resolved or improved spontaneously, with no recurrence at mid-term follow-up.