OPTIMAL EXPANSION OF THE MULTILINK STENT - AN IN-VITRO STUDY USING DIRECT MAGNIFICATION RADIOGRAPHY

It has been speculated that high pressure implantation may improve the results of coronary stenting. However, this method bears the risk of peristent dissection and may increase late lumen loss. Presently, ther e is no consensus about the optimal stent implantation technique with the regard to balloon size and pressure. To elucidate this question an experimental study was performed in a coronary stenosis model. 3.5 mm Multi-Link (ML) stents were implanted in 3.3 mm silicone rubber tubes containing 50% concentric narrowings. Three implantation techniques w ere applied: 1. The standard technique using the conventional ML deliv ery system with a compliant balloon (ML-ST). 2. A new deployment metho d with a high pressure delivery system (ML-HP). 3. ''Focal postdilatio n'' using the ARC catheter, which has a special balloon with an inner compliant and an outer non-compliant section (ML-ARC). For comparison, the Palmaz-Schatz stent was implanted by using a high pressure balloo n. Stent expansion was imaged by magnification radiography. Minimal lu men diameter within the stent (MLD) and the lumen diameter outside the stent (BD) were measured after dilations with 6, 9, 12, 15, 18, and 2 1 atm. The relation of the ED to the MLD was used as an index of vesse l trauma. The results lead to following conclusions: 1. A complete app osition to the vessel wall for a balloon/vessel relation of 1.1:1 coul d not be reached with pressures below 9-15 atm. The increase of the pr essure beyond 15 atm resulted only in a minimal additional lumen. 2. C ompared to the Palmaz-Schatz stent the recoil of the ML stent was sign ificant lower. 3. For all three implantation techniques the ML-ARC sho wed the best results with the maximal dilatation of the stenotic vesse l-area and the minimal expansion of the vessel outside the stent.