Electrophysiology Paul Wang, MD Amin Al-Ahmad, MD ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos Power Steered Catheter.

Electrophysiology

Paul Wang, MDAmin Al-Ahmad, MD

ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos

Power Steered Catheter Control System

Karlin Bark, Marlo Dreissigacker, Gabriel Sanchez, Dan Santos

Electrophysiology and Arrhythmia

• Electro-physiologists detect abnormal electrical pathways in the heart by recording electrical activity within the heart chambers

ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos

Non-Surgical Procedure

Catheter insertion point

ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos

Current State of the ArtManual

ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos

• Multi-Degree of Freedom– Bi-directional – Torsion Control– Telescoping Tip

• Increased Mapping Area– Ring of Contacts– Balloon Catheter

Current State of the ArtRobotic

• Hansen Medical– Robotically Controlled

Catheter

ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos

Clinical Need Finding• Surgeon “wish-list”

– More comfortable and simple to use– Easier control of distal tip– Finer positioning resolution of distal tip– Larger range of motion of distal tip– Tactile feedback

• Statements– “uncomfortable”, “tiring”, “fingers hurt”, “not intuitive at all”

ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos

Current design problems• Simple mechanical designs:

– Manual positioning limits accuracy– Physically taxing user-interface– Uncomfortable user-interface

• Advanced robotic designs:– Not intuitive– No direct tactile feedback– Requires re-training

ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos

Design Specifications• Focus on manual input device that doctor uses• Specifications:

– Electromechanical - Smart Mechanical Drive– Bi-directional control– One-handed operation - familiar to doctors– In-line structure – Non-backdriveable

ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos

Smart Mechanical Drive

ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos

Internal motor actuates push-pull cables based on doctor’s input

Power Steering

Input Mechanism

ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos

• Linear Slide• Axially Symmetric• Low Friction

Electronics

ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos

µControllerPIC

MotorDriver

LinearSensor

LimitSwitches

PowerSupply

• Proportional Speed Control• Dead-band Throttle• Travel Limits

Demonstration

ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos

Design Improvements

• Decrease overall size• Manual override• Increase speed

smaller diametershorter length

manual overridelarger pitch

spring mechanism

ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos

• Advanced Control• Self-Centering Ring

Conclusions

• Less physical effort to use• Similar motion and interface: no additional training• Could transition into real-world market easily

– Minor change on existing, common device– Only a small increase in cost

• +$50 for a device that costs $600-$1000+

ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos

Acknowledgements

• Dr. Paul Wang, Dr. Amin Al-Ahmed, Bryant Lin• Craig Milroy and Raj Doshi• Laura Melton

ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos

Questions?

ME294: Medical Device Design Autumn 2005 Bark, Dreissigacker, Sanchez, Santos