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Background MRI-guidance for cardiovascular catheterization is appealing to reduce ionizing radiation exposure and to enable novel procedures. “Active” guidewire-antennas for MRI-guided procedures are often designed such that the tip and shaft have distinct signals [1] to improve navigation and to make it obvious when the tip moves out of plane. Here we present a method to isolate the signal from iron markers, and produce a two channel color overlay for visualizing the shaft and tip of a nitinol guidewire.

Background Transcatheter aortic valves have benefitted from device miniaturization and in-situ assembly to reduce delivery system caliber and enable trans-vascular delivery. In contrast, investigational transcatheter mitral prostheses are bulky devices that require large caliber access ports. Trans-apical delivery is undesirable because of increased morbidity associated with rib spreading, closure site bleeding and impact on left ventricle (LV) function. Trans-septal delivery is challenging because of the acute angle required to reach the mitral valve. A ‘straight shot’ to the mitral valve (Fig 1A) that does not violate the LV myocardium is preferable, both in terms of device engineering and patient outcome. We hypothesized that with realtime MR guidance and by deflating a lung, it is possible to access the left atrium (LA) directly through the posterior chest wall, and close the access port using off-the-shelf nitinol devices.