Power steering: A system for more capable catheters

Posted on 06. Oct, 2011 by in Academic Departments, Annual Report, Healthcare and Medicine, Issues, Mechanical Engineering, Research

Nicola Ferrier and Michael Zinn

Nicola Ferrier and Michael Zinn. Photo: David Nevala.

Atrial fibrillation is a condition where the upper chambers of a patient’s heart beat irregularly, which can cause blood to pool and increase the risk of stroke-causing clots. Treatment is difficult: A physician has to maneuver a catheter around a patient’s chest cavity to the diseased regions of the heart, which are then frozen or burned.

A robotic catheter is articulated and moves in and out. In theory, a clinician controls it by pulling on the cables that run along the outside of the catheter, but in reality, friction develops and robs the cables of tension. This is a particular problem when clinicians are trying to operate the catheter in an open body cavity rather than snaking the device through a vein or artery. “There isn’t a one-to-one relationship in how much you pull and the catheter’s response,” says Mechanical Engineering Assistant Professor Michael Zinn, (pictured, with Nicola Ferrier) who is investigating model-based control strategies to improve the performance and efficacy of these catheters.

Zinn is developing a closed-loop control system that will adjust a catheter electronically to go where a physician directs it and correct for errors. He is collaborating with Mechanical Engineering Professor Nicola Ferrier to develop better imaging of a catheter during a procedure. Current imaging is done via X-rays, which can’t be delivered continuously to patients, so physicians can only view the catheter intermittently. Zinn and Ferrier are merging the benefits of various computer- and radiation-based imaging technologies to develop more advanced techniques to determine where a catheter is at all times.

Along with developing the algorithms and sensing techniques and implementing them in hardware, Zinn’s team is modeling the new device and studying the underlying physics of how the catheter moves.

Improved catheter control has applications in any minimally invasive procedure that uses a flexible robotic device. Creating a more seamless and intuitive system may broadly expand the number of doctors who will use these technologies, Zinn says. “Current catheters are resigned to poor performance. If successful, this could significantly increase the capabilities of most types of flexible robotics and increase the effectiveness of procedures that use them,” he says.

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