Purpose: Pulmonary vein isolation using cryoballoon ablation is an established approach to treating atrial fibrillation. The procedure involves insertion of a 15-Fr sheath into the left atrium across the interatrial septum. This creates an iatrogenic atrial septal defect, which may have important long-term clinical relevance, especially in younger patients. We sought to determine the long-term incidence of these defects and determine the direction of shunt using contrast transesophageal echocardiography.
Methods: Individuals who had undergone a single pulmonary vein isolation procedure were invited to attend for transesophageal echocardiography (TOE). Patients who had undergone more than one procedure involving puncture of the interatrial septum were excluded. The interatrial septum was interrogated using two-dimensional imaging, color flow Doppler, and microbubble contrast study.
Results: A total of 27 patients were recruited with a median follow-up time of 553 days from pulmonary vein isolation to TOE. Seven patients had persistent iatrogenic atrial septal defects with three demonstrating right to left shunt either at rest or with Valsalva. There were no reported adverse events during the study period.
Conclusions: Persistent iatrogenic atrial septal defects are relatively common following cryoballoon ablation procedures. Right to left shunting can be observed using microbubble contrast in a subset of patients with iatrogenic atrial septal defect (iASD). Further studies that longitudinally assess shunt fraction, pulmonary artery pressure, and the incidence of paradoxical embolism are needed to better understand the clinical impacts of such defects.
Keywords: Atrial fibrillation; Atrial septal defect; Pulmonary vein isolation.