Percutaneous device occlusion of secundum atrial septal defects (ASDs) is becoming an accepted alternative to surgical closure. This method allows us to evaluate patients with complex conditions for treatment. From a total of 70 patients with ASD evaluated for percutaneous closure, we selected for analysis 28 who had complex conditions. The mean age was 36+/-23 yr (range, 4-72). Six had heart failure, and of these six, three had atrial fibrillation. At cardiac catheterization, the pulmonary pressure was 47+/-24 mm Hg, and the QP/QS was 1.7+/-0.4; two patients had bidirectional shunt and systemic pulmonary pressure. Two patients received a buttoned device and 26 an Amplatzer septal occluder. The groups of patients with complex conditions were separated into the following groups. Group I (n = 4) underwent combined treatment of associated anomalies. Two patients had pulmonary stenosis, one had mitral stenosis, and one had an aortic root-left atrium fistula. They were treated in or during with the same procedure by combined transcatheter techniques (balloon valvuloplasty and fistula occlusion) before ASD occlusion. Group II (n = 9) had multiple defects (cribiform or two separate holes). They were treated with a single device in five instances and with two separate devices in four cases. Group III (n = 14) had large (32+/-3 mm) single defects. Nine of them underwent successful implantation using a device 33+/-3 mm in diameter; in the remaining five patients the device was removed because of instability. Group IV (n = 3) had residual defects after previous partial device occlusion. All three defects were successfully occluded with a second device. No movement or interference with the first device was observed. Group V (n = 6) had severe pulmonary hypertension (86+/-16 mm Hg). Immediately after ASD occlusion we observed significant relief in these patients (67+/-14 mm Hg; P<0.01). There were no major complications; all 23 patients with successful implants were discharged without symptoms 2-7 days later; one patient with atrial fibrillation recovered sinus rhythm. The follow-up (8+/-5 mo) Doppler echo study showed complete ASD occlusion in 22 patients and a peak pulmonary pressure of 30+/-14 mm Hg. We conclude that transcatheter occlusion of ASDs is an effective and safe treatment for patients with complex anatomic or physiopathologic conditions, as evaluated by short-term follow-up.