No abstract

PurposeThromboembolic complications remain a limitation of flow diverting stents. We hypothesize that phosphorilcholine surface modified flow diverters (Pipeline Flex with Shield Technology, sPED) would have less acute thrombus formation on the device surface compared with the classic Pipeline Embolization device (cPED).MethodsElastase-induced aneurysms were created in 40 rabbits and randomly assigned to receive cPED or sPED devices with and without dual antiplatelet therapy (DAPT) (four groups, n=10/group). Angioplasty was performed to enhance apposition and create intimal injury for a pro-thrombotic environment. Both before and after angioplasty, the flow diverter was imaged with intravascular optical coherence tomography. The outcome measure was the number of predefined segments along the implant relative to the location of the aneurysm with a minimum of 0 (no clot formation) and maximum of 3 (all segments with thrombus). Clot formation over the device at ostia of branch arteries was assessed as either present or absent.ResultsFollowing angioplasty, the number of flow diverter segments with clots was significantly associated with the flow diverter (p<0.0001), but not with DAPT (p=0.3872) or aneurysm neck size (p=0.8555). The incidence rate for clots with cPED was 1.72 times more than with sPED. The clots on the flow diverter at the location corresponding to side branch ostia was significantly lower with sPED than with cPED (OR 0.180; 95% CI 0.044 to 0.734; p=0.0168), but was not associated with DAPT (p=0.3198).ConclusionIn the rabbit model, phosphorilcholine surface modified flow diverters are associated with less thrombus formation on the surface of the device.

The use of OCT to assess CM of flow diverters has been shown to be predictive of the 30 day healing rate of an animal model of aneurysms.

Micelle formation in water and adsorbed film formation at the air/water interface were investigated by surface tension measurement of a mixed surfactant system: the combination of sodium salt of R-sulfonatomyristic acid methyl ester (R-SMy‚Me) with decanoyl-N-methylglucamide (MEGA-10). R-SMy‚ Me and MEGA-10 can form well-mixed micelles with the aid of a strong interaction between headgroups, and accordingly the critical micelle concentration (cmc) as a function of mole fraction of MEGA-10 in the surfactant mixture (XMEGA10) deviates negatively from ideal mixing. The micellar phase curve (cmc-YMEGA10 relation) was simulated by using the interaction parameter ωR ) -2.1; the curve indicated the existence of an azeotrope formed by a 3:2 mixture (at XMEGA10 ) YMEGA10 ) 0.4). Further, we derived equations related to the composition in the adsorbed film (Zi) equilibrated with monomers in bulk solution and to the interaction parameter (WA), and then constructed a phase diagram including two relations of cmc vs XMEGA10 and cmc vs ZMEGA10. From the diagram an azeotrope was found to be formed by the 1:1 mixture (at XMEGA10 ) ZMEGA10 ) 0.5), suggesting that the composition in micelles (Yi) differs from that in the adsorbed film (Zi). The surface tension (γ) vs logarithmic molality (ln m) curve at every 0.1 increment in XMEGA10 showed synergistically enhanced surface activity. From the slope of the γ vs ln m curve just below cmc, the surface excess (Γ) was determined and then the mean molecular area (Am) was calculated as a function of XMEGA10. By analysis of Am data, the partial molecular area (PMA) of each component was determined as a function of XMEGA10; this also showed a large deviation from ideal mixing (the additivity rule).