1. Cauterizing Conductive Catheter for Percutaneous and/or Vascular Intervention
Brad Wood, M.D.
Charles Blyth
Cristina Fernandez
Scott Hittinger
Cameron Jones
Brian McGee

2. National Institute of Health
NIH
“NIH is the steward of medical and behavioral research for the Nation. Its mission is science in pursuit of fundamental knowledge about the nature and behavior of living systems and the application of that knowledge to extend healthy life and reduce the burdens of illness and disability.” (

3. Our Project
Catheter material selection, design, and testing for nephrostomies, biliary tubes, and possibly the vascular tree.
Conductivity
Deliver RF pulse via catheter, not a needle
Dielectric Constants
Maxwell’s Equations
Biocompatibility
Maneuverable!
Practicality
Price
Ease of manufacture
Use in the OR

4. Past Attempts Biopsy Environment Only High RF Pulse
Cauterize after biopsy
Tissue damage
RF tip on a metal needle inserted through the catheter.
Collagen/Fibrin Plug
Pull Biopsy needle, inject compound
Impractical
Expensive

5. Biopsy Approach Fig. 2 – Left  no plug Right  with plug1
Fig. 1 – Fibrin Plug Injection1
Fig. 3 – High frequency RF ablation2
Paulson et al. “Use of Fibrin Sealant as a Hemostatic Agent after Liver Biopsy in Swine”. Hepatic Intervention 2000.
Pritchard et al. “Radiofrequency Cauterization with Biopsy Introducer Needle”. Journal of Vascular Interventional Radiology 2004.

6. Specifics
Current catheters are Polyparaxylylene (PPX) which cost approximately $13 a piece or more and is not a conductive material.
RF pulse upwards of 100 kHz
Testing for biopsy procedure uses 200W, 480 kHz RF generator (CCI Cosman coagulator system, Radonics, Burlington, MA)
“Radiofrequency cauterization with introducer needle”. JOURNAL OF VASCULAR INTERVENTIONAL RADIOLOGY :

7. Let’s Burn Someone
Cauterization of 1mm +/- 0.5mm outside of the catheter – assumes no cooking within the catheter
70˚C – 100˚C – this value is based on the cauterization temperature of tissue and the possible melting temperatures of many biocompatible materials.
“Radiofrequency cauterization with introducer needle”. JOURNAL OF VASCULAR INTERVENTIONAL RADIOLOGY :

8. Size Does Matter 5 French (5F) catheters - .038 inch diameter
1-2 mm in diameter
Currently using 2.0mm Tru-Cut needles or 1.6mm Jamshidi needles for biopsy procedures. (just a reference size)
Current biopsy RF pulse ablation
Animal testing with 14 gauge, 10cm coaxial introducer needle.

9. Our Turn
So lets find something with these properties that will make for a useful, practical, RF pulse generating catheter!
“Surgical glues and sealants are expected to significantly take over sutures and staples in the next 10 years.”
September 24, 1998 – “Marine Polymer Technologies”

10. Closure Devices/Companies
Epotek
AngioSeal
StarClose – produced by Abbott Vascular
Syvek
Kumpe Access Catheter – from Cook Urological

11. Timeline

12. Current Work
Looking into all companies and material properties of promising compounds for catheter manufacturing
Conducting Silicone based material
Conducting Polyurethane material
Focusing in on most important aspects of thermal properties, biocompatibility (toxicity, density, maneuverability), and in contact with Dr. Wood’s colleagues regarding thermal calculations regarding heat loss, and other colleagues regarding current volume loss of urine (nephrostomies) and blood (liver and vasculature).

13. Future Steps Obtain possible biomaterials for production of catheters.
Create prototype
TEST IN COW LIVER!!!
Approach VU individuals about biomaterials for possible solution.
Proof of Concept