[First results with catheter and magnetically guided and detached polymerized ferromagnetic particle filaments and heat-induced particle release using the Stereotaxis Niobe system]

Abstract

Purpose: To develop a new technique for intravascular guidance and the release of magnetized ferromagnetic nanoparticles using a polymerized filament by means of an external magnetic field.

Materials and methods: Ferromagnetic nanoscaled beads were embedded in temperature-sensitive gels to form filaments after polymerization. Deflection of the filaments was assessed in a Stereotaxis Niobe magnetic navigation system (MNS) in comparison with dedicated guide wires. The curvature was measured as a surrogate parameter for deflection. In combination with commercially available catheters, the filaments were navigated in a perfused aneurysmatic vessel model and a perfused branched vessel model under the influence of two permanent magnets of the Niobe MNS. The magnetic field vector was varied in all three dimensions. After positioning, the magnetic colloid-containing filaments were exposed to an electromagnetic field of 45 kA/m, 200 kHz for a period of 5 minutes for non-invasive heating.

Results: The filaments showed superior deflectability compared to the dedicated guide wires (p = 0.0091). The curvature was 0.54 +/- 0.12 mm(-1) for the filaments and 0.33 +/- 0.21 mm(-1) for the guide wires. In combination with angiography catheters, magnetic guidance and accumulation of specially designed filaments were possible in the perfused vessel model. Inductive heating allowed non-invasive disintegration and releasing of the nanoparticles in all filaments.

Conclusion: This feasibility study shows that magnetic guidance and targeting of a specially designed magnetic colloid-containing filament and subsequent disintegration are feasible. This technique offers the potential for controlled local drug release.