How Stereotaxis developed this first-of-its-kind EP mapping catheter

Stereotaxis recently reported the first commercial cases using its FDA-cleared for MAGiC Sweep, which the device developer says is the world’s first robotically navigated high-density electrophysiology (EP) mapping catheter.

The minimally invasive medtech developer also developed a CE-marked ablation catheter under the same MAGiC name, which is an abbreviation of magnetic interventional ablation catheter. Both MAGiC catheters are designed for use with Stereotaxis robotics systems.

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Stereotaxis said in FDA filings that the new MAGiC Sweep catheter has 19 electrodes and one tip electrode, with three different electrode spacings and 20 different magnet spacings for each electrode spacing configuration.

“The variety of configurations facilitate the navigation of the device to specific areas of the heart and facilitate recording of intracardiac signals and/or stimulation in the atrial and ventricular regions of the heart during electrophysiology studies,” Stereotaxis said in its FDA 510(k) submission.

Medical Design & Outsourcing asked Stereotaxis Director of Clinical Engineering and New Concepts Nathan Kastelein to discuss the new interventional catheter, including the components that make it possible, development challenges and solutions, and advice for other medical device designers and engineers.

The following has been lightly edited for space and clarity.

MDO: What’s the big advance that makes the MAGiC Sweep catheter possible?

Kastelein: “Utilizing small magnets in the design allowed us to manage how the shaft of the device responded to the guiding magnetic fields. This allows the shape of the shaft to be controlled and bend in such a way that the mapping electrodes can acquire the surface data effectively. All the other typical advantages of using magnetic fields — such as the consistent and steady application of an optimal amount of force when touching the heart — allows for stable signals, less physical distention of the heart wall, less ectopy, and a better risk profile compared with a manual device.”

What’s unique about neodymium magnets and why did you select them for this application?

Kastelein: “Cardiac catheters are small devices by design. They typically need to include design features such as location sensors, thermocouples, electrodes, wiring, and irrigation channels. When you add magnets to the list of required parts, you obviously need highly performing magnets in a small package. Rare earth magnets made with neodymium provide a strong magnetic moment in a small package that can be shaped into useful parts for inserting into the interior of a cardiac catheter. The strong response of these magnets is what enables precise shaping and placement of the MAGiC Sweep catheter without the need for pull wire mechanisms. The result is an atraumatic catheter design that avoids anatomic distention and delivers outstanding electrode-tissue contact as the catheter is essentially held against the tissue by the magnetic force.”

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How did Stereotaxis develop MAGiC Sweep and what were the biggest technical challenges and solutions along the way?

Kastelein: “Stereotaxis has had a great deal of success and excellent clinical outcomes with robotic magnetic therapeutic ablation catheters, along with an enviable safety record when compared with manual devices. The challenge in developing the MAGiC Sweep catheter was how to apply this skill and experience to a multi-polar diagnostic mapping catheter. While similar in materials and shape, the motions and maneuvers needed to create a high density electro-anatomical map are different than for a therapeutic ablation catheter.

“With an ablation catheter, the objective is to move the tip of the device to where the therapy needs to be delivered. With a multi-polar mapping device, the objective is to lay the shaft of the device along the endocardial surface so that the many electrodes along the shaft can capture the electrical data from many points on the heart’s surface. To do this, we used computer modeling and physical prototyping to assess various potential approaches to multi-polar mapping using the magnetic navigation system.”

Can you tell us more about that modeling and prototyping and applications for other devices or systems?

Kastelein: “The approach of using computer modeling to test design feasibility followed by evaluating a range of physical devices with different design characteristics is certainly a powerful way to converge on a functional design. The experience with the development of MAGiC Sweep just emphasizes that both modeling and physical prototyping work together to dial-in the characteristics of the design. Models are very useful especially in the early stages, but models often have missing elements or built-in assumptions that only become apparent when evaluating physical devices. Likewise physical devices provide a tremendous amount of practical knowledge, but building prototypes is costly and takes time so is not a great way to do early-stage evaluations. Finding this balance and recognizing the value of each step translates to many other types of device development efforts.

“The development of Sweep has definitely increased our technical knowledge and intellectual property. Increased experience with a broader range of robotically-steered interventional devices and is contributing to our continued robust pipeline of R&D efforts. We look forward to bringing many more catheter innovations to patients and physicians in the coming years.”

What advice would you offer to medical device designers and engineers based on what you’ve learned in your own career?

Kastelein: “One of the main things I’ve observed over years of device development is that the road from an idea to realizing a successful clinical tool is a long and challenging one. In addition to the many engineering decisions and design trade-offs, seeing success in devices requires a strong business sense, regulatory awareness, clinical experience, and physician relationships. Successful engineers in the medical device field need to have a broad understanding of this entire range of skills. Many innovative devices never make it, not always because of the design or technology, but because these other parts of the equation were not well managed. Engineers would benefit from spending time working with the business, regulatory and clinical parts of a company. Additionally, listening to and observing the physicians that are working to overcome clinical challenges is invaluable for device engineers. The work that engineers do and how that work is performed has a big impact on the clinical, regulatory, business and marketing aspects required for a successful product. To say their knowledge must be all-encompassing is an understatement, but it is so rewarding when it all comes together.”

Related: Why Stereotaxis says magnets are so attractive for minimally invasive medtech