Background: According to present knowledge, pulmonary vein isolation(PⅥ) bears a low interventional risk and has a high feasibility. For completion of PⅥ, left atrial access is achieved via single or double transseptal puncture. We sought to determine the incidence and echocardiographic characteristics of persistent iatrogenic atrial septal defect(iASD) after PⅥ. Further objectives were to define clinical and periprocedural risk factors for the development of iASD. Methods: Every patient admitted for PⅥ at our hospital was screened for eligibility for study participation. Exclusion criteria were inability for undergoing transesophageal echocardiography, preexisting atrial septal defect, open-heart surgery or another transseptal procedure during the follow-up period. Transesophageal echocardiography was performed before PⅥ and after 9 months. Interatrial shunt was characterized by echocardiographic parameters; right-to-left shunting(RLS) was quantified by contrast echocardiography. Results: Forty-two patients were included, 27 patients underwent PⅥ with single transseptal puncture and additional advancement of a second electrophysiologic catheter(group A), 15 patients underwent PⅥ with double transseptal puncture(group B). In 8 patients of group A, iASD persisted after the follow-up period, including 6 patients with distinct RLS. We saw no iASD in group B(P=.011, CI-0.79 to-0.11). Preprocedural pulmonary artery pressure was significantly higher in patients with iASD and accompanying RLS, compared with patients with iASD and no evidence of RLS(23.75±0.50 vs 17.59±5.82, P=.048, CI 0.048-12.27). Conclusion: This is the first study that demonstrates a high incidence of long-term persistent iatrogenic atrial septal defect with RLS after PⅥ. All interatrial shunts occurred after single transseptal puncture with passage of 2 electrophysiologic catheters into the left atrium. Increased preprocedural pulmonary artery pressure seems to promote the occurrence of RLS across iASD. Background: According to present knowledge, pulmonary vein isolation (PVI) bears a low interventional risk and has a high feasibility. For completion of PVI, left atrial access is achieved via single or double transseptal puncture. We sought to determine the incidence and echocardiographic characteristics Methods: Every patient admitted for PVI at our hospital was screened for eligibility for study participation. Exclusion criteria were inability (iASD) for undergoing transesophageal echocardiography, preexisting atrial septal defect, open-heart surgery or another transseptal procedure during the follow-up period. Transesophageal echocardiography was performed before PVI and after 9 months. Interatrial shunt was characterized by echocardiographic parameters; right-to-left shunting (RLS) was quantified by contrast echocardiogr Aphy. Results: Forty-two patients were included, 27 patients underwent PVI with single transseptal puncture and additional advancement of a second electrophysiologic catheter (group A), 15 patients underwent PVI with double transseptal puncture (group B). In 8 patients of group A, iASD persisted after the follow-up period, including 6 patients with distinct RLS. We saw no iASD in group B (P = .011, CI- 0.79 to-0.11). Preprocedural pulmonary artery pressure was significantly higher in patients with iASD and accompanying RLS, compared with patients with iASD and no evidence of RLS (23.75 ± 0.50 vs 17.59 ± 5.82, P = .048, CI 0.048-12.27). Conclusion: This is the first study that demonstrates a high incidence of long-term Persistent iatrogenic atrial septal defect with RLS after PⅥ. All interatrial shunts occurred after single transseptal puncture with passage of 2 electrophysiologic catheters into the left atrium. Increased preprocedural pulmonary artery pressure seems to promote the occurrence of RLS across iASD.