Three-Degree-of-Freedom MR-Compatible Multisegment Cardiac Catheter Steering Mechanism.
This paper presents a novel MR-compatible 3-DOF cardiac catheter steering mechanism. The catheter's steerable structure is tendon driven and consists of miniature deflectable, helical segments created by a precise rapid prototyping technique. The created catheter prototype has an outer diameter of 9 Fr (3 mm) and a steerable distal end that can be deflected in a 3-D space via four braided high-tensile Spectra fiber tendons. Any longitudinal twist commonly observed in helical structures is compensated for by employing clockwise (CW) and counter clockwise (CCW) helical segments in an alternating fashion. A 280 μm flexible carbon fiber rod is used as a backbone in a central channel to improve the structure's steering and positioning repeatability. In addition to the backbone, a carbon fiber tube can be inserted into the structure to a varying amount capable of changing the structure's forcibility and, thus, providing a means to change the curvature and to modify the deflectable length of the catheter leading to an extension of reachable points in the catheter-tip workspace. A unique feature of this helical segment structure is that the stiffness can be further adjusted by appropriately tensioning tendons simultaneously. An experimental study has been conducted examining the catheter-tip trajectory in a 3-D space and its positioning repeatability using a 5-DOF magnetic coil tracking system. Furthermore, MRI experiments in a 1.5-T scanner confirmed the MR-compatibility of the catheter prototype. The study shows that the proposed concept for catheter steering has great potential to be employed for robotically steered and MR-guided cardiac catheterization.
Asghar
A
Ataollahi
Rashed
R
Karim
Arash Soleiman
AS
Fallah
Kawal
K
Rhode
Reza
R
Razavi
Lakmal D
LD
Seneviratne
Tobias
T
Schaeffter
Kaspar
K
Althoefer
D006328:Cardiac Catheterization / Q000295:instrumentation*; D062906:Cardiac Catheters; D004867:Equipment Design; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D019047:Phantoms, Imaging; D065287:Robotic Surgical Procedures / Q000295:instrumentation*