ASD device closure as a modality is constantly improving . . . but the consensus is , it is yet to catch up with of good old surgical outcome . The key to success is not only in the device but hugely dependent on the technique and pre-procedure evaluation .In fact , the pre procedure TEE imaging technique is as important as the procedure itself.
There are lots of discussion about this particular issue. TEE is mandatory we know but now we realise it is still better to have a Real time 3dimensional (RT3D ) TEE . Rim size and ASD morphology estimation is the primary aim.
There are at least 6 named rims for ASD. For a circular orifice it may not be logical to have a fixed number of 6 rims . Ideally the entire circumference must have a rim .( This happens in central defects )In many, the complex anatomy of IAS does not allow this. So we are compelled to fix the number of rims to six.
- Aortic (Superoanterior),
- Mitral (AV valve/ Inferoaterior)
- SVC (Superoposterior),
- IVC (Inferoposterior),
- Posterior ( Atrial free wall ).
- Coronary sinus rim
One can realise how important these rims are , as they are the foundation tissues on which the device is going to be seated for the rest of the patients life.
When do you call a rim is adequate sized ?
5mm is considered suffice. But it varies depending upon the device and expertise.
Can we deploy an ASD device in patients with deficient rims?
Logically the answer is expected is “No” but , many have liberalized the criteria now , after realizing one may not have 5mm rim in all six sites in a given patient. If you follow this criteria strictly you can’t do more than few devices a year !
What is the resolution power of TEE can it miss a 3mm rim ?
TEE has a good resolution it should pickup any thing equal to 2mm or more.
Which is most important rim and which is the least important rim ?
What are the potential complications that can arise if ASD device is deployed with a critically low rim ?
Having discussed that every rim is equally vital , we need to answer this sort of questions often . I am waiting to get the practical tips for the above issue from my experienced colleagues . I shall post it soon .
It is sometimes assumed Aortic rim may not be that important .Here is a good discussion for ASD closure with deficient aortic rim from Saudi Arabia . http://www.rmsolutions.net/rmfiles/SHA21/028002.pdf
Meanwhile let us learn . . .
How to perform the “all important” pre- procedure TEE ?
The following article which also includes video clippings will be immensely useful for all those enthusiastic cardiologists.Thanks to JACC for making this link free .
Three cheers to AMRITA team from India
A stylish article on the topic