Background: In recent years percutaneous, transcatheter closure of atrial septal defects (ASD) or patent foramen ovale (PFO) was introduced into clinical practice. Objective: To investigate the functional effects on heart valves caused by an interatrial closure device. Methods and results: Between 2001 and 2006, 240 consecutive patients underwent percutaneous closure of an ASD or a PFO. Heart valve functions were defined by transoesophageal echocardiography before implantation and 3, 6 and 12 months after defect closure. A successful implantation procedure was performed in 98% of patients. Sufficient closure without residual shunt was achieved in 89% of patients with ASD and in 92% of patients with PFO. An overall major complication rate of 0.8% was apparent during the observation time (mean (SD) 27 (15) months). Long-term follow-up disclosed newly developed or worsened aortic valve regurgitation (AR) in 9% of patients with ASD and in 10% of patients with PFO. A potential cause for developing AR may be overgrowth of the device by tissue, leading to changes in interatrial septal geometry and traction on the root of the non-coronary aortic cusp. Conclusion: AR occurred in 9% of patients with closed ASD and in 10% of patients with closed PFO. Indication for closure should consider this potential complication despite an otherwise safe interventional procedure.