Wireless monitoring: Medtronic's implanted defibrillators get FDA approval

Medtronic's implanted defibrillators, the Concerto cardiac resynchronization therapy-defibrillator (CRT-D) and Virtuoso implantable cardioverter defibrillator (ICD), utilize a WLAN to send their data to the patient's landline Internet service to relay this information to the clinician, as reported by Unstrung.

The two new devices are the first implantable cardic regulators that use Medtronic's Conexus wireless system, which runs over the 402-405MHz frequency, a band known as the Medical Implant Communications Service.

This alleviates the problem of interference with clinical monitoring devices that use the 900MHz band which could present a problem where many devices are in use, such as in a hospital setting.

Medtronic will also be performing a clinical trial over the next 18 months to test their devices in detecting fluid accumulations in the thorax which might lead to the ability to monitor both acute and chronic diseases including congestive heart failure or pericardial and pleural effusions. This indication has been approved in Europe.

Here's a section from the press release posted on their Web site (They list a Web site www.MedtronicConexus.com but it's not available at this time.):

The Virtuoso ICD and Concerto CRT-D help track and manage heart failure symptoms. They also will deliver a shock to terminate a dangerously abnormal heart rhythm. The Concerto CRT-D device also sends tiny electrical impulses to the heart muscle to resynchronize the contractions of the heart’s lower chambers, helping the heart pump blood throughout the body more efficiently. Other features include:

• Conexus Wireless Telemetry with SmartRadio™: Utilizing the MICS radio frequency band, Medtronic Conexus Telemetry enables reliable communication between the patient’s implanted device and home monitor or clinician programmer at a range of two to five meters (approximately six to 16 feet). The MICS band is a frequency designated by global telecommunications regulatory authorities, such as the Federal Communications Commission, for implantable medical device communication. Use of the MICS band protects Medtronic wireless devices from interference caused by cell phones and other common wireless devices, providing a level of protection that cannot be offered by systems that use other frequencies.

• OptiVol® Fluid Status Monitoring: OptiVol measures changes in impedance in the thoracic cavity, the chest area encompassing the lungs and heart. 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 can provide important insights used in conjunction with ongoing monitoring of other patient symptoms. Previously available on the Medtronic InSync Sentry™ CRT-D device, OptiVol is now available to Virtuoso ICD patients as well as Concerto CRT-D patients.

• Left Ventricular Capture Management: LVCM, available on the Concerto CRT-D, is intended to automatically sense and adjust impulses for optimal stimulation of the heart’s lower left chamber (ventricle) and ensure cardiac resynchronization therapy.

• ATP During Charging™: Automatically uses pacing pulses to painlessly stop fast, dangerous heartbeats, while concurrently preparing to deliver a shock if needed, with no delay. Medtronic PainFREE™ Therapy has been clinically proven to eliminate three out of four shocks with painless pacing therapy. ATP During Charging is now available for both CRT-D and ICD patients.

• Managed Ventricular Pacing: MVP™ Mode, available on the Virtuoso DR (dual chamber) ICD, promotes intrinsic conduction and reduces right ventricular pacing by 99 percent (median).

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