Case Study: Kodak EktaPro HS motion analyser 4540ra

Boston Scientific’s pioneering work in treatments to prevent heart attacks uses high speed digital camera technology to design...

Boston Scientific’s pioneering work in treatments to prevent heart attacks uses high speed digital camera technology to design minute surgical tools

Heart disease affects over 13 million Americans, killing almost 500,000 of them each year. While there are many causes, heart attacks, strokes and damaged tissue can all occur when arterial plaque build-up remains undetected. Thanks to today's medical advances, combined with sophisticated digital imaging tools to design life-saving products, excessive plaque build-up does not automatically translate into a death sentence.

Boston Scientific's Northwest Technology Centre in Redmond, Washington, manufactures a product, the Rotablator Rotational Atherectomy System, that is designed to remove plaque from arterial walls using a tiny football-shaped burr that spins its way through the plaque to disintegrate it. Each hand-made burr is 1.25-2.50mm in diameter, is coated with microscopic diamonds, and spins at speeds up to 200,000 revolutions per minute (rpm) to grind away plaque deposits.

Precise motion analysis is a key component of the research and development (R&D) process at Boston Scientific. Engineers use a high-speed motion analyser from Kodak to help design and enhance the company's plaque-eating Rotablator Rotational Atherectomy System. This analysis has been instrumental in developing multiple generations of increasingly effective burrs. Additionally, the use of a motion analyser has reduced development time and cut costs.

Engineers use the Kodak EktaPro HS motion analyser, model 4540 (the Kodak high-speed analyser) as an integral part of the R&D process at Boston Scientific. The camera is used to study the rotation of the burr and the motion of the drive shaft that connects the burr to the turbine in the device. R&D engineers also use the camera to analyse concepts for new shapes of burrs and rotating parts. By analysing the motion of the burrs, engineers can develop more effective ways of removing the plaque deposits.

The burr is connected to a turbine and bearing assembly, which rotates at speeds up to 200,000 rpm, giving the burr a surface speed of about 65 mph. The high-speed camera makes it possible to see aspects of the Rotablator's catheter motion at work, from proper spinning motion to damaging lateral motion or vibration, at a variety of slow motion speeds.

The Rotablator's catheter turbine can drive a cyclic oscillation that causes a wavy snake-like motion in the catheter driveshaft. This can't be monitored by the naked eye. The Kodak high-speed analyser, however, allows engineers to see how long a vibrational mode is on a drive shaft and watch the movement of the spinning burr.

At 40,500 frames per second, engineers can capture 15 images during every revolution of the burr. In this application, engineers can simulate an actual procedure, watching a specific spot on the burr come around and make contact with a simulated plaque deposit. This detailed movement of the burr can be viewed on a video monitor at a variety of playback speeds as slow as one picture per second, as well as freeze frame, to give engineers a detailed look at the burr's position.

The biggest enemy of the burr is lateral motion. It reduces the efficiency of the burr exponentially. Energy lost to vibration and lateral motion in the drive shaft does not reach the end of the burr. This lateral type of vibration will also irritate the inside of the patient's artery.

In one situation, a prototype burr underwent observation. To the naked eye, the burr and drive shaft seemed to operate perfectly. However, some unexplainable results occurred during the preliminary tests. Using the high-speed camera, engineers immediately discovered that the experimental shape of the burr was causing poor performance.

The design of this particular burr was immediately scrapped. Without the use of the Kodak high-speed camera, it could have taken up to a year for Boston Scientific engineers to assess the true nature of the problem. The time savings were worth up to $1 million in research costs, one of the reasons Boston Scientific purchased a high-speed motion analyser specifically for the R&D group.

Initial operator training takes around 30 minutes, and R&D engineers were using the motion analyser in the laboratory very quickly. Additionally, the model 4540-motion analyser has several useful features. Instant feedback is available from digital images stored in memory. These images can be reviewed on a monitor, downloaded to standard videotape for future reference or transferred to a PC for image analysis. The Boston Scientific set up consists of halogen fibre lights with the subject shot at a distance of one to two feet.

Currently, engineers use the camera on as many as 10 projects per day. Some projects require use of the camera for two to three days at a time, taking advantage of the instant feedback to change designs and check performance of the re-designed components.

This motion analysis system has become one of the mainstays of Boston Scientific's R&D department because it has helped the company save money, reduce production time and deliver a more efficient product. By combining a high-speed camera from Kodak with their design engineers' expertise, Boston Scientific has developed a tool to help reduce the risk of heart disease resulting from plaque build-up.

Compiled by Will Garside

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