Originally used in early 1990s, self expanding coronary stents (Wall stent from Boston scientific ) subsequently lost interest because of delivery related issues. Many feel , it makes cardiologist judgment tentative and delivery system prevail over our hand skills. It is possible stents can longitudinally jump with high radial force making a geographical miss more likely.While it could be true with any technique till we master it, one should recall ,most endo-vascular work other than coronary still involve self expandable techniques.
Balloon expandable stent is ruling the PCI field for more than 2 decades. There has been recent surge of interest in the self expanding technique and it could make a great difference in the PCI arena provided we take the proper cues.
Self expanding stents have some unique advantage
- It has high radial force.
- Approximation with lesion is best
- It tends to take the shape of the vessel than any other stent
- Since the mal-opposition and gap between stent and vessel wall is minimal stent thrombosis is theoretically is lower.
Where is self expanding stent useful ?
- Ectatic and very irregular lesions
- Bifurcation lesions where multi dimensional vessels with different shaped ostia converge.
- Eccentric lesions (Non calcified) may be benefited by self expanding stents
- Self expanding covered self (Is it available >) may be the best bet for perforations and for thrombus to be plastied against the wall.
- In some small vessels PCI
- Finally it may have a role in primary PCI (APPOSITION 1 to 5 )
What are the self expanding stents available ?
- Devax system ( 2003)
- Radius (Boston scientific)
- Capella Sideguard.
- Cardiomind Sparrow
- vProtect luminal shield.
For some reason , self expanding stents were not tested widely and large scale data is not available. However , they are unique modalities in metal delivery and must be mastered and many patient subsets will be benefited by it. They are not obsolete yet, APPOSITION 5 study will answer some of the issues.