Flow-driven magnetic microcatheter for superselective arterial embolization.

Minimally invasive interventions performed inside brain vessels with the synergistic use of microcatheters pushed over guidewires have revolutionized the way aneurysms, strokes, arteriovenous malformations, brain tumors, and other cerebrovascular conditions are being treated. However, a substantial portion of the brain vasculature remains inaccessible because the conventional catheterization technique based on transmitting forces from the proximal to the distal end of the instruments imposes stringent constraints on their diameter and stiffness. Here, we overcame this mechanical barrier by microengineering ultraminiaturized magnetic microcatheters in the form of an inflatable flat tube, making them ultraflexible and capable of harnessing the kinetic energy of blood flow for endovascular navigation. We introduce a compact and versatile magnetic steering platform that is compatible with conventional biplane fluoroscope imaging and demonstrate safe and effortless navigation and tracking of hard-to-reach, distal, tortuous arteries that are as small as 180 micrometers in diameter with a curvature radius as small as 0.69 millimeters. Furthermore, we demonstrate the superselective infusion of contrast and embolic liquid agents, all in a porcine model. These results pave the way to reach, diagnose, and treat currently inaccessible distal arteries that may be at risk of bleeding or feeding a tumor. Our endovascular technology can also be used to selectively target tissues for drug or gene delivery from within the arteries, not only in the central and peripheral nervous systems but also in almost any other organ system, with improved accuracy, speed, and safety.