ASDs are classically oval, but devices are typically circular.(Exact Incidence of ovoid ASD is not known. but it easily exceed 50 % .(Recall, the embryologically ill-fated hole expands around the fossa ovalis not circularis )
Do we have Oval devices ?
I think, we don’t have one . Please check from this list , a good document on ASD device implantation from Poland
Why do we accept this shape mismatch ? What are the potential issues because of that ?
When closing non-circular ASD, the size of device should be considered according to the multiple diameters of the defect. One diameter of the circular device could be too large for the shortest diameter causing a deformity in residual rims. The cardiac erosion after successful implantation as one of the most important complications due to a larger device in the oval defect compared to the circular defect (This text was taken from (Ref 1)
Why the idea ovoid device was never popular ?
Technical issues in sizing the exact oval defects ,device company’s lack of interest. However, designer devices with perfect fit with the help of 3D printing is very much possible.
Is it true ,an Oval device might hold good even in the setting of deficient IVC or posterior rim ?
May be. Some truth in it. I am not an expert to comment.
Do we really require a perfect fit devices ?
When I discussed with an expert , he said there is no need for oval device . A large circular device 2mm larger than the long axis diameter of the oval orifice is not an issue at all . Some how, find it difficult to accept that. What about you readers ? Please respond if you have any comments.
Any study on this issue ?
Yes. one study specifically looked into this. It compared the effect of circular device on oval defects. It concluded there no difference in any adverse outcome , but oversizing is unavoidable with oval defect.. This study , though addressed a vital query ,is never meant to find the truth we want, as it has no oval vs circular device to compare the outcome.
Final message
It is strange ,cardiologists look for perfection and precision in every cardiac intervention, … while in case of ASD device closure, size is sacrosanct, but shapes, we are allowed to shrug off. May be things will change.
Reference
2.Roberson DA, Cui W, Patel D, Tsang W, Sugeng L, Weinert L, et al. Three-dimensional transesophageal echocardiography of atrial septal defect: a qualitative and quantitative anatomic study. J Am Soc Echocardiogr. 2011;24:600–610. [PubMed] [Google Scholar]
Dr.S.Venkatesan MD 