We read with interest the report by Masura et al. [1] on the initial clinical results of transcatheter closure of secundum atrial septal defects, using the new self-centering Amplatzer septal occluder (ASO) device. The authors report closure of 30 atrial septal defects using the ASO device. After deployment of the device, assessment of device position and residual shunt was performed by transoesophageal echocardiography. The report includes a photograph of the final levophase pulmonary angiogram in one patient. However, there is no mention of whether angiography was performed in all patients and, if so, what the results were. The ASO prosthesis has a relatively ''open'' design and is constructed from nitinol wires woven into flat buttons with polyester material sewn in. An important mechanism of leakage-proof closure is the polyester augmented secondary thrombosis. Keeping these two facts in mind, and also that all patients were heparinized, it is likely that an immediate postprocedure pulmonary angiogram would show significant right atrial opacification. As the amount of blood passing through the woven nitinol fibers postdeployment would be relatively small and of low velocity, echocar-diographic techniques may not be sensitive enough to pick this up.
If pulmonary angiogram levophase studies were, in fact, done immediately after device deployment in all patients, it is important for future users of this device to know what they showed. If most studies showed right atrial opacification, this finding need not be considered to signify procedural failure, as almost all defects in this report had closed by the time of 3-month follow-up. On the other hand, if most studies did not show right atrial opacification, the presence or degree of right atrial opacification may be of significance and needs to be correlated with the follow-up results obtained.