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.