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Year of Innovation

Fri, 09/30/2005 - 11:51am
One year ago this month, Medical Design Technology was relaunched as a feature-based publication with a new look, style, and size. Thanks to the support of both readers and leaders in the medical device field, the magazine has had a successful year delivering critical information about some of the most important trends in the industry. To celebrate this anniversary, this month’s cover article takes a look at how the technologies covered in these pages over the last 12 months are being put to use in the real world.


On the cover: The first product to employ Artelon material is the Artelon CMC-I Spacer from Small Bone Innovations. It’s used to cure arthritis in the base of the thumba condition that affects 30 percent of all women and 10 to 15 percent of men over 50.
AT A GLANCE
  • Medical device trends and issues
  • Latest product development news
  • Intravascular Implantable Defibrillator
  • The PillCam
  • Artelon CMC-I Spacer
  • Actipore porous metal technology
  • Embrace heart stabilizer
By Peter Cleaveland, West Coast Editor
It has been one year since Medical Design Technology adopted its new look, and since that time we have covered many new technologies, numerous advances in existing technologies, and scores of exciting medical device introductions. To celebrate this one-year anniversary, this month’s cover article provides an update on several of the technologies that were “in the news” this past year.
Speaking to Implants
The cover story in the October 2004 issue of Medical Design Technology, “Inside Implantable Devices” by Carl Falcon of AMI Semiconductor (AMIS), discussed the Medical Implant Communications Service (MICS) classification from the Federal Communications Commission. MICS allows radio communication between medical implants and control devices outside the body. It offers faster data transfer rates and a longer range than earlier magnetic-inductive-coupling techniques. MICS systems operate in the 402-405 MHz band, and the implantable devices use just a few microwatts of power, giving an overall communications range of a few feet. Very low power is used both to prevent interference with other equipment and to allow implant batteries to last for seven to 10 years.


Figure 1: AMI Semiconductor’s current MICS product is the AMIS-52100 Application Specific Transmit and Receive IC.
In October of 2004, the first MICS-enabled devices were still under development. Ed Goffin, communications manager, corporate communications at Zarlink Semiconductor, reports that the base station version of the company’s ZL70100 MICS chip is now in production and sampling with customers, while the implantable-grade version of the same chip is going through final stages of qualification and will be available later this year. “Following that development,” says Goffin, “we will be introducing a module that integrates the MICS chip with an antenna.”

These chips are currently in prototype designs with a number of medical device customers, Goffin continues. “The lead product is an ICD [implanted cardiac defibrillator] using the transceiver chip, and we expect that device will be on the market in roughly 12 months. Several other manufacturers are looking at the device for use applications that can take advantage of the MICS band and wireless monitoring or control, such as pacemakers, implanted drug infusion systems, and bladder control.”

In April, AMIS announced a technology design and supply partnership with specialist cardiology company Interventional Rhythm Management Inc. (IRM). Under the agreement, AMIS will provide custom low-power mixed-signal ASIC solutions that will be used in IRM’s cardiac electrophysiology devices such as implantable defibrillators and pacemakers. IRM’s initial product will be the Intravascular Implantable Defibrillator (IID) designed for the primary prevention of sudden cardiac death. Instead of being implanted under the collarbone, the device is inserted through the left femoral vein and secured into the inferior vena cava, without major surgery. “It’s a much simpler and faster procedure and the number of physicians who can do the implant may be increased five or six times versus the very limited number of cardiac electrophysiologists,” says Mike Rice, medical marketing and business development manager at AMIS.


Figure 2: The PillCam from Given Imaging takes a series of photographs or even streaming video as it moves through the gastrointestinal track.
AMIS’s current product is the AMIS-52100 Application Specific Transmit and Receive IC illustrated in Figure 1.Another device that uses MICS is the PillCam (Figure 2) from Given Imaging. The PillCam is a miniature camera system built into a capsule. The patient swallows the PillCam capsule, and its miniature camera system takes a series of photographs or even streaming video as it moves through the gastrointestinal track, sending the images by MICS RF link to an external data recorder.

The thought of communicating with a medical implant whose performance is life-critical might cause some people to wonder about possible problems with electromagnetic interference, but Rice points out that one of the best-publicized problems with an ICD occurred with an inductively coupled unit. In this particular device, he says, a magnetic switch intended to sense “when the magnetic or inductive coil is placed over the patient’s chest [in order to] start ... the data extraction or the programming mode” locked up. “Even though the number of incidents ... is very small,” says Rice, “just the amount of press related to that I think will drive an accelerated conversion to MICS and RF technology versus inductive.”
Conserving Energy
The batteries in an implanted device must last as long as possible, which makes it essential to reduce power consumption to the absolute minimum. The AMIS MICS chipset does this by spending most of its time in a so-called “sniff mode.” The receiver in the implant spends most of its time asleep. Every 0.5 to 16 seconds, it wakes up and listens to find out if it is being interrogated. If it detects no signal, it goes back to sleep. The entire process takes less than 100 s. Figure 3 illustrates this process.


Figure 3: The AMIS MICS chipset saves energy by spending most of its time in a “sniff mode.” Every 0.5 to 16 seconds, it wakes up and listens. If it detects no signal, it goes back to sleep.
The potential market for MICS-enabled devices is large, with about a million CRM (cardiac rhythm management) devices implanted every year, plus perhaps 125,000 to 150,000 neurostimulation devices and 80,000 to 90,000 PillCams. “There is really a whole evolution of devices from open or just basically blind stimulus to the closed-loop systems or sensor systems [that] will all require that devices be able to receive updated software and/or programming instructions by a physician,” says Rice. “And the devices are increasing in their memory capacity because now physicians want to take a look at more than just very small snapshots in time of patient data; they’d like to look at longer samples to observe trends and perhaps adjust the clinical diagnosis or treatment protocol.”
Sterilizing with VHP
The December 2004 issue of Medical Design Technology featured an article by David B. Vogel, director of validation and microbiological control at Smith & Nephew Orthopaedics Inc. “Bringing Sterilization Inside” discussed the use of a vaporous hydrogen peroxide (VHP) system, shown in Figure 4, from Steris Corp. for sterilization in place of ethylene oxide.


Figure 4: Steris Corp.’s VHP MD2000 is an example of a vaporous hydrogen peroxide sterilizer.
Ethylene oxide (EtO) is an effective sterilizing agent, but it’s a hazardous material, both flammable and highly reactive. “Acute exposures to EtO gas may result in respiratory irritation and lung injury, headache, nausea, vomiting, diarrhea, shortness of breath, and cyanosis. Chronic exposure has been associated with the occurrence of cancer, reproductive effects, mutagenic changes, neurotoxicity, and sensitization,” according to OSHA. EtO is also the active ingredient in the military’s thermobaric bomb (fuel-air explosive), which is useful in clearing land mines and killing enemy fighters hiding in caves. EtO’s toxicity requires a time-consuming neutralization process using special equipment after use, which is a pretty good reason to look for an alternative.

VHP produces no toxic substances (its end products are oxygen and water vapor) and thus requires no environmental controls. “We could put it in-house without all the environmental controls you need for ethylene oxide,” says Vogel. In addition, its cycle time can be less than three hours.

Concentrated hydrogen peroxide (H2O2) is a strong oxidizer and catalytically decomposes by contact with many substances, including many metals, to produce heat (steam) and oxygen. It is believed that the destruction of the Russian submarine Kursk began with leaks of high-test peroxide (HTP) used in the propulsion systems of torpedoes. Vogel admits that the company’s environmental staff had some early misgivings about it, thinking that the H2O2 would be delivered in 55-gallon drums. “But,” he says, “since it comes in its own self-contained bottle and the operators never even open the bottle, their concerns were limited after that.” The amount used per cycle is smallabout 30 gramsand what’s in the bottle is 35 percent H2O2, about the concentration found in a college chemistry lab, and not the 85 percent plus material used by the military. Smith & Nephew buys it in 950-ml bottles, six bottles to a case. “We’ve never had any more than one case in-house at any one time,” says Vogel.

Vogel reports that Smith & Nephew has had such success with the first unit they installed that they are installing a second, slightly larger unit. While they originally had planned for certification for parametric release, that hasn’t been done yet. “It’s one of those studies that got pushed to the back,” he says.
Flexible Circuits
One of the basic technologies for building medical devices is the flexible circuit. Using thin sheets of flexible plastic (generally polyimide), a circuit can be put together that takes less room and has more flexibility in packaging than is available from rigid PC boards. “The very thin makeup of flexible circuit layers gives them some extra room in places for other things,” says Merle Tinglestad, marketing manager for flexible circuits at Minco. “They can get all their circuit density that they need with the flexible circuits and not have to have the thickness that a rigid board would provide.”


Figure 5: Many heart pacers and defibrillators save space by using flexible circuits.
Smaller packages also are easier to implant. Many pacers and defibrillators, such as the one depicted in Figure 5, can be implanted in 30 minutes to an hour, often in a catheterization lab, on an outpatient basis. Tinglestad expects this trend to continue. “There will be more flexible circuits used as the main driver board within these implantable devices,” he says. “There are still a number of manufacturers, and particularly within the pacemaker device, that are still using rigid circuits. They’re using some flex for auxiliary and for things where they need to bend around, but their main motherboard in a lot of cases may be rigid circuits.”

Tinglestad also expects more manufacturers to adopt hybrid designs. “When flex manufacturers are replacing rigid circuits, normally they’re replacing them with a hybrid of rigid and flex material, so you don’t save all of the thickness of the FR4 but you save a few layers, and you eliminate some connections that they need to make. The primary advantage of the flex in these devices is that it can work in the 3D world, whereas the rigid circuits are confined to the two-dimensional world.”

More information on flexible circuits is available by reviewing this month’s Emphasis article titled “Technological Trends Influencing Electronic Medical Implant Devices”.
New Implant Material
One of the more interesting developments of the past year has been the introduction of Artelon, a biodegradable implant material developed by Artimplant AB. Artelon is a biodegradable polyurethane urea copolymer with a six-year biodegradation profile. The FDA cleared it in September 2004, and it was introduced to the market in 2005. The first product using the material is the Artelon CMC-I Spacer, shown in Figure 6, from Small Bone Innovations LLC, used to cure arthritis in the base of the thumba condition that affects 30 percent of all women and 10 to 15 percent of men over the age of 50. In basil joint arthritis, the ligaments that stabilize the carpometacarpal or basilar joint of the thumb (between the metacarpal and trapezium) loosen with time, allowing too much sliding of the joint surfaces and wearing down the joint cartilage.


Figure 6: The Artelon CMC-I Spacer from Small Bone Innovations LLC is used to treat basilar arthritis of the thumb. It is made of Artelon, a biodegradable implant material developed by Artimplant AB.
There are several artheroplasty procedures to deal with this condition. One is ligament reconstruction tendon interposition, also called the anchovy procedure. In this procedure, says Shawn Huxel, global vice president, tissue technology systems, Small Bone Innovations, “they’ll take a ligament to reconstruct the joint, to give it the support structure it needs, and then they will resect the trapezium, then roll up the tendon, and stuff it in there.” While this gives immediate relief from pain and restores mobility to the thumb, it has some drawbacks, he continues. “The patient has lower strength in her thumb, she has the morbidity associated with the harvest of the tissue, she has some thumb shortening and some thumb deformity that happens downstream.”

The Artelon CMC-I Spacer, which looks like a piece of fabric doubled in the middle with the loose ends splayed out, is used in stages 1 through 3 of the disease, in which some cartilage still remains in the joint. The wings, which provide support, are fastened to the adjacent bones of the jointthe first metacarpal and the trapeziumand the double-layer vertical portion goes into the joint space. The Artelon material provides a scaffold, and with time the wings are ingrown with bone and the vertical portion is ingrown with cartilage to resurface the joint.

At this point, the longest clinical trials have gone on for five years, and the results are encouraging. Small Bone Innovations is also looking to use the Artelon material in the distal joints of the fingers and toes, and Artimplant has gained FDA approval of Artelon sutures. The Artelon material is also available as a porous foam.

Small Bone Innovations has other plans that involve porous material, according to Chairman and CEO Anthony Viscogliosi. The company has acquired the worldwide license for the exclusive use of the Actipore porous metal technology from Biorthex Inc. Actipore is a porous titanium-nickel material that encourages “through-growth of bony tissue when used in apposition to bone and rapid ingrowth of bone tissue cells,” he says. “This kind of material can be widely applicable,” he continues, especially in places like fingers where damage can be extensive and there is not much bone to work with. In such cases, Viscogliosi says, “a material like the Biorthex porous metal technology can increase the surface area contact up to 10 times.”
Holding A Beating Heart

Figure 7: The Embrace heart stabilizer sold by CardioVations, a division of Ethicon Inc., involved two design companies: Strategix Vision and Herbst LaZar Bell.
The article “Products for Tomorrow,” contributed by Robert R. Andrews of Foster-Miller Inc. in the April 2005 issue, discussed the use of outside companies as design partners to speed the development of new products. A good example of this can be seen in the development of the Embrace heart stabilizer illustrated in Figure 7. This device, sold by CardioVations, a division of Ethicon Inc., a Johnson & Johnson company, is used to hold the heart in position during cardiac bypass surgery. Keeping the heart and the coronary artery in a fixed position makes it possible to perform bypass surgery without stopping the heart and maintaining the patient on a heart-lung machine. CardioVations quotes a May 2002 study by Medtech Insight that estimated that off-pump coronary artery bypass (OPCAB) is used in 25 percent of all coronary bypass surgeries.

Claimed advantages for OPCAB include quicker recovery, preservation of cognitive function, shorter hospital stays, and fewer major complications such as stroke and infection. Studies have found that survival rates for patients given OPCAB surgery were comparable to that of on-pump surgery, and that it was more cost-effective.

Two design companies were involved with the Embrace stabilizer: Strategix Vision and Herbst LaZar Bell Inc. “HLB provided Human Factors analysis of the revascularization process, performed observational research to understand high-value features and benefits, and developed configurations,” according to HLB Senior Vice President Charles Keane. In June of this year, the design won a gold Industrial Design Excellence Award presented by the Industrial Designers Society of America and co-sponsored by Business Week magazine.
Final Thoughts
Since October 2004, the editorial staff of Medical Design Technology has assembled a monthly review of some of the most fascinating technologies influencing the medical device manufacturing industry. By publishing articles written by authoritative sources as well as by interviewing key experts and writing reports on the latest technical developments and real-world applications, the editors are providing readers with an ever-growing “library” of need-to-know information. Much more is coming, so stay tuned.
ONLINE
For additional information on the technologies and products discussed in this article, see Medical Design Technology online at www.mdtmag.com and the following websites.
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