Computer Modeling of Bending the Ascenda® Catheter
Intrathecal Catheters
® for Targeted Drug Delivery: Computer Modeling of Bending the Ascenda Catheter Elizabeth Kregel, BBME, Mike Walz, BBME, Amy Nelson, BBME, Tom Conway, PhD, MSME Medtronic, Minneapolis, MN
BACKGROUND Intrathecal catheters must be soft, pliable, and of small diameter, but also remain stable and patent to function as intended for targeted drug delivery in the intrathecal space.
Engineering Testing on the Benchtop
Physician Input
Due to complex implant and use conditions, a simulated bending load was chosen where the inner angle of the kinked catheter was evaluated numerically. This is illustrated in Figure 5.
Figure 3: Iterative Testing Methodology Polyurethane Outer Layers Silicone Inner Layer Polyester Braid Figure 1: Ascenda® Intrathecal Catheter Design Kinking of the pliable catheter tubing is a possible undesired consequence during clinical use conditions (catheter placement within the in vivo tissue environment). Observational analyses of a subset of returned intrathecal catheter products with possible kinks identified three primary locations along the catheter where potential kinks could be observed (Figure 2). DISTAL TO ANCHOR
Medtronic engineering, scientific, and medical staff began with formalized brainstorming activities followed by analysis of field complaints and returned products. These process inputs led to multiple, iterative benchtop tests to recreate the clinical environment. Physicians were also involved in the review of findings and results.
Replicating Clinical Scenarios on the Benchtop
PROXIMAL TO ANCHOR
Computer Modeling of Catheter Bending
CT Scanning of Catheter Kinks
Figure 5: DOE Output – Inner Angle at Kink Point Scanning Electron Microscope Analysis Data Mining and Trending
Design of Experiment (DOE) methods were used to analyze each treatment combination. A sharp change in the deflection of the curve indicated a kink as seen in Figure 6. The corresponding inner angle as well as reduction in the inner lumen cross-sectional area was recorded. Figure 7: Two Modes of Inner Lumen Cross Sectional Area Reduction using Simulated Modeling: General Reduction (left) and Buckling (right)
Figure 4: Various Methods to Understand Catheter Kinking
NEAR CATHETER TO CATHETER CONNECTOR
Figure 2: A Review of Returned Products Revealed that Kinking is Primarily Localized to Three Areas
Computer simulation showed that the angle at which the catheter kinks is easily determined as well as the reduction in inner lumen cross-sectional area. Significant factors, such as individual layer thicknesses, were determined to affect catheter kinking. In the computer simulated model, when the test segment length was reduced to one inch, the catheter layers were more likely to buckle, which was the intended outcome of the simulation. Figure 7 shows a general reduction in inner lumen area compared to a buckling of the inner lumen.
Various methods were used throughout the process, and this poster will focus specifically on computer modeling of catheter bending.
Ascenda Catheter Kinking
RESULTS
METHODS
CONCLUSIONS
A 3D finite element analysis (FEA) model was created to simulate bending of the Ascenda® catheter. Factors including individual catheter layer dimensions and material properties were examined to determine what types of variables may affect catheter kinking.
OBJECTIVE: Continue to build in-depth understanding of intrathecal catheter clinical performance, focusing on the potential occurrence of kinking via computer modeling.
Poster 99 | January 19-22, 2017 2017 Annual Meeting of the North American Neuromodulation Society, Las Vegas, Nevada, USA
Continued analysis of the potential for catheter kinking will occur through ongoing testing and SEM analysis. The goal of this study is to identify opportunities for best practices in implant technique and, if needed, further product enhancements. Figure 6: Determining when the Catheter Kink Occurs
® for Targeted Drug Delivery: Computer Modeling of Bending the Ascenda Catheter Elizabeth Kregel, BBME, Mike Walz, BBME, Amy Nelson, BBME, Tom Conway, PhD, MSME Medtronic, Minneapolis, MN
BACKGROUND Intrathecal catheters must be soft, pliable, and of small diameter, but also remain stable and patent to function as intended for targeted drug delivery in the intrathecal space.
Engineering Testing on the Benchtop
Physician Input
Due to complex implant and use conditions, a simulated bending load was chosen where the inner angle of the kinked catheter was evaluated numerically. This is illustrated in Figure 5.
Figure 3: Iterative Testing Methodology Polyurethane Outer Layers Silicone Inner Layer Polyester Braid Figure 1: Ascenda® Intrathecal Catheter Design Kinking of the pliable catheter tubing is a possible undesired consequence during clinical use conditions (catheter placement within the in vivo tissue environment). Observational analyses of a subset of returned intrathecal catheter products with possible kinks identified three primary locations along the catheter where potential kinks could be observed (Figure 2). DISTAL TO ANCHOR
Medtronic engineering, scientific, and medical staff began with formalized brainstorming activities followed by analysis of field complaints and returned products. These process inputs led to multiple, iterative benchtop tests to recreate the clinical environment. Physicians were also involved in the review of findings and results.
Replicating Clinical Scenarios on the Benchtop
PROXIMAL TO ANCHOR
Computer Modeling of Catheter Bending
CT Scanning of Catheter Kinks
Figure 5: DOE Output – Inner Angle at Kink Point Scanning Electron Microscope Analysis Data Mining and Trending
Design of Experiment (DOE) methods were used to analyze each treatment combination. A sharp change in the deflection of the curve indicated a kink as seen in Figure 6. The corresponding inner angle as well as reduction in the inner lumen cross-sectional area was recorded. Figure 7: Two Modes of Inner Lumen Cross Sectional Area Reduction using Simulated Modeling: General Reduction (left) and Buckling (right)
Figure 4: Various Methods to Understand Catheter Kinking
NEAR CATHETER TO CATHETER CONNECTOR
Figure 2: A Review of Returned Products Revealed that Kinking is Primarily Localized to Three Areas
Computer simulation showed that the angle at which the catheter kinks is easily determined as well as the reduction in inner lumen cross-sectional area. Significant factors, such as individual layer thicknesses, were determined to affect catheter kinking. In the computer simulated model, when the test segment length was reduced to one inch, the catheter layers were more likely to buckle, which was the intended outcome of the simulation. Figure 7 shows a general reduction in inner lumen area compared to a buckling of the inner lumen.
Various methods were used throughout the process, and this poster will focus specifically on computer modeling of catheter bending.
Ascenda Catheter Kinking
RESULTS
METHODS
CONCLUSIONS
A 3D finite element analysis (FEA) model was created to simulate bending of the Ascenda® catheter. Factors including individual catheter layer dimensions and material properties were examined to determine what types of variables may affect catheter kinking.
OBJECTIVE: Continue to build in-depth understanding of intrathecal catheter clinical performance, focusing on the potential occurrence of kinking via computer modeling.
Poster 99 | January 19-22, 2017 2017 Annual Meeting of the North American Neuromodulation Society, Las Vegas, Nevada, USA
Continued analysis of the potential for catheter kinking will occur through ongoing testing and SEM analysis. The goal of this study is to identify opportunities for best practices in implant technique and, if needed, further product enhancements. Figure 6: Determining when the Catheter Kink Occurs
