Medical Device Daily Associate

A potentially revolutionary new feature may soon be added to Medtronic s cardiac resynchronization therapy defibrillator (CRT-D) line if a new trial being conducted in the U.S. and other sites around the world proves successful.

The company reported the first implants in the U.S. of its Concerto CRT-D with atrial therapies (AT).

The clinical study, dubbed Concerto-AT, is a prospective, non-randomized, multi-center, global clinical trial involving up to 425 patients at up to 50 sites in Europe, the U.S and Japan. The purpose of the study is to assess the safety and efficacy of atrial defibrillation therapy in patients with a current indication for CRT and ICD.

The Concerto/Virtuoso line of implantable devices, which includes the Concerto CRT-D and Virtuoso implantable cardioverter-defibrillator (ICD), will be Medtronic s first cardiac rhythm management products with Conexus Wireless Tele-metry.

Conexus, which utilizes the medical implant communication service (MICS) radio frequency band, 402-405 MHz, is designed to enable communication between a patient s implanted device and home monitor or clinician programmer at a range of 6 feet to 16 feet.

According to George Crossley, MD, chief of electrophysiology at Baptist Hospital (Nashville, Tennessee), whose center is involved in the trial, the Conexus telemetry will enhance efficiencies at device implant and during in-office follow-up visits, as well as enable automatic, wireless data transmission from the patient s device to a home monitor.

The biggest advantage [of the Concerto CRT-D], other than just convenience for us, is when we start using remote telemetry at home, he told Medical Device Daily, adding that the device has an enormous amount of diagnostic capability.

He said one of the primary components of the device is a sensor that the company calls the OptiVol. He said this sensor is able to detect the amount of fluid in a congestive heart failure patient s lungs and chest.

Crossley said that when the new device finally gets the regulatory green light to perform remote transmission from a home monitor, doctors envision that patients will be able to come within range of their home monitor in the evening before bed-time and the system will scan their implanted CRT-D device, looking for any potential problems.

Their home monitor will look for flags or alarms in the device, [and] if it sees them it will do a full interrogation and send that to the doctor in a way that s totally transparent to the doctor and the patient, he said.

Specifically, the Optivol measures changes in impedance in the thoracic cavity. Using very low electrical pulses that travel across the thoracic cavity, the system can measure the level of resistance to the electrical pulses, which indicates the level of fluid in the thorax.

Since normal fluid levels may vary from patient to patient, and fluid accumulation can be either slow or rapid, OptiVol s ability to measure fluid status trends over time may provide important insights that are used in conjunction with ongoing monitoring of other patient symptoms.

Device data from the home monitor will then be transmitted to the clinician using the company s CareLink Network, an Internet-based system to help physicians and patients better manage chronic cardiovascular disease treated by implantable device therapy.

The early work on this fluid monitor would suggest that it s a good early warning system for congestive heart failure, said Crossley, adding that while we really need more data to prove that concept, it s a pretty darn simple concept . . .it s just [basic] physics.

The company sees the device as a key component of its plans for the future of healthcare management.

The Concerto AT device, with Conexus Wireless Telemetry, represents a technological turning point for Medtronic and our industry, said Steve Mahle, president of Medtronic Cardiac Rhythm Management. This system makes full use of the Medtronic CareLink Network as the cornerstone of our platform for wireless communication, and transforms CareLink from a device management tool to a disease management tool.

While the wireless component already is being utilized in a hospital setting, Crossley noted that the home monitoring devices have still not been activated for the trial, due to some pending regulatory and manufacturing issues with the home monitoring device.

Speaking from his experience in the hospital setting, he said the device had appeared to perform very well, especially considering that the hospital setting is an electronically noisy place.

That fear of noise interference led the company to incorporate another important differentiator into the Concerto product design, the MICS band.

The MICS band is a dedicated frequency designated by global telecommunications regulatory authorities, such as the Federal Communications Commission in the U.S., for implantable medical device communication. Use of the MICS band is intended to protect Medtronic wireless devices from interference caused by cell phones and other common electronic devices.

Crossley said that incorporating the MICS band into the Concerto products added time to the development. However, he predicted problems for a Medtronic competitor, which elected to save time in the development of its wireless telemetry system by using an off-the-shelf product that utilizes a 900 MHz frequency.

That s the same frequency that hand-held home phones, cell phones and some other telemetry systems use. I really think that Medtronic did the right thing even though it made the development cycle close to a year longer to use [the MICS] frequency.

Interestingly, Medtronic was not required to test any of the other devices in the Concerto/Virtuoso family of products that incorporate the same wireless telemetry.

The only device that FDA made them go through a full clinical trial is this combination device that has everything in it, said Crossley.

He noted that the wireless telemetry component has already been studied extensively on the bench, at hospitals all over the U.S. and Europe in incredibly challenging environments like next to a CT scanner or MRI machine and performed very well. We couldn t make it fail at all.

Crossley said he expects that the Concerto CRT-D with AT will be available in the near future, and that it could potentially change the way patients with CHF are managed.

When we get to the end of the road here and have remote telemetry at home, I really am convinced that we ll have something very special and that very much diminishes the cost of healthcare in the heart failure patient.

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