What Determines the Three-Dimensional Trajectory of Chronic Total Occlusion (CTO) Guidewires? An Engineering Study of the Principles of CTO-guidewire Control.

PURPOSE: This study was performed to establish the equivalence between the differential-geometry osculating plane of the chronic total occlusion (CTO)-guidewire (GW-Although GW is typically used as an abbreviation for guidewire, in this paper it is used specifically as the abbreviation for CTO-guidewire) trajectory and the GW osculating plane-defined as the plane spanned by the direction vectors of the GW tip-shaft and the GW tip-and to clarify the operating principles of GW manipulation by demonstrating that the GW osculating plane prescribes the three-dimensional GW trajectory. METHODS: A GW was manually advanced into a CTO model through controlled rotation and pushing. At an arbitrary point A, the GW tip and tip-shaft were imaged using a cardiovascular X-ray system. Using vectors derived from two angiographic images taken at different view angles, the normalized direction vectors of the GW tip and tip-shaft were obtained to calculate the normalized normal vector of the GW osculating plane. The approximation function of the three-dimensional GW trajectory near point A was derived from X-ray images, and the tangent and principal normal vectors at A were calculated to determine the normalized normal vector of the differential-geometry osculating plane. Thirty experiments were conducted to statistically evaluate the equivalence of the normal vectors of both osculating planes. RESULTS: In all 30 experiments, the normals of the GW osculating plane and the differential-geometry osculating plane were statistically equivalent. CONCLUSION: These findings provide strong evidence that the GW osculating plane coincides with the differential-geometry osculating plane under the tested conditions, supporting their interchangeability for predicting the three-dimensional GW trajectory.