In this review, we describe the experience from 13 European centres using the CardioSEAL and Starflex double umbrella devices to close interatrial communications within the oval fossa (so-called 'secundum' defects). Between October 1996 and April 1999, the procedure was attempted in 334 patients with a mean age of 12 years and a mean weight of 44kg. The mean measured stretched diameter of the defect was 15 mm. In the overall group, the defect was solitary in 245 patients (73%), multiple in 21 (6%), associated with an aneurysm of the flap valve in 15 (5 %), was represented by patency of the oval foramen in 44 (13%), and was a fenestration in a Fontan repair in 9 (3%). In all patients, the devices were inserted under general anesthesia, using fluoroscopic and transesophageal echocardiographic control. Implantation was achieved in 325 (97,3%). The device embolized within either a few minutes or a few hours in 13 patients (4%). Of these, uncomplicated surgical repair was undertaken in 10, while the device was retrieved in 3 using catheters and a second device was successfully implanted. Residual shunting was detected immediately after the procedure in 41% of the patients, with the incidence decreasing to 31% at discharge, 24% at 1 month, 21% at 6 months, and 20.5% at one year. During the period of follow-up, elective surgical repair became necessary in two patients, due to malposition of the device in one, and late embolization in the other. Fractures of arms were seen in 6.1 %, most commonly with the largest devices. All those with fractured arms of the device were asymptomatic, and no clinical complications related to the fractures were observed. There were no arrhythmias, endocarditis, valvar distortion, thromboembolic events, or other complications. After one year of follow-up, clinical success, defined as complete closure of the defect or presence of only a trivial leak, had been obtained in 92.5% of the patients. We conclude, therefore, that these devices produce excellent results when used to close defects of small to moderate size. Results are less than optimal, or else complications ensure, when attempts are made to close very large defects.