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Consciousness of Blood Pressure Is Rising as Details About Possible Remedies Continue to Evolve: First Patients Implanted With Wireless Pressure Sensor for Hypertension Monitoring


First Patients Implanted With Wireless Pressure Sensor for Hypertension Monitoring

A proprietary miniature wireless pressure sensor has been successfully surgically implanted into the wrists of 3 severely hypertensive patients, the first time such a device has been used to monitor blood pressure in the management of hypertension.[25] The procedure was carried out at the Hospital Dipreca (Santiago, Chile) by cardiothoracic surgeons Miguel Luis Berr, MD, and Michael Tuchek, DO.

The wireless hypertension sensor is a proprietary miniature device developed by CardioMEMS (Atlanta, Georgia) to be positioned just below the surface of the skin above the patient's radial artery using a minimally invasive procedure. The sensor is designed to allow for a precise and accurate measurement of systemic blood pressure using the CardioMEMS proprietary electronics module. Following the procedure, the sensor and electronics are designed to allow for additional blood pressure measurements to be taken by the patients at home and to transmit the data wirelessly to a secure database where it will become available for review on CardioMEMS' patient management Web site. The wireless hypertension sensor and the related electronics are being evaluated as part of a clinical trial and are not approved for marketing. Following the first implantations, Dr. Berr commented, "As with our previous experience with the CardioMEMS sensor, the device was simple to implant and we expect that the information provided will be very useful in the management of this disease."

Jay S. Yadav, MD, Chairman and CEO of CardioMEMS, says that precise home monitoring of blood pressure using this device should allow patients to have greater control over managing their own health and also provide additional information for physicians regarding treatment effectiveness." With colleagues Mark G. Allen, PhD, and David R. Stern, BS, ME, Dr. Yadav, formerly Chairman of Cleveland Clinic Innovations and Director of Vascular Intervention at the Cleveland Clinic (Cleveland, Ohio), and cofounder of CardioMEMS, has developed a proprietary wireless sensing and communication technology platform designed to improve the management of severe chronic cardiovascular diseases such as heart failure, aneurysms, and hypertension.

The monitoring technology is composed of 2 components: a miniaturized, wireless implantable sensor and an external electronics module. The external electronics module wirelessly communicates with the sensors to deliver vital patient data. The wireless sensors are powered by radiofrequency energy transmitted from an external electronics module and transmit real-time data without batteries. The sensors are designed and manufactured using microelectromechanical systems (MEMS) technology, which enables the fabrication of millimeter-scale devices with internal features in the nanometer to micrometer range.

The external electronics module consists of 3 parts: the internal signal processing electronics, or main unit; the antenna used to wirelessly communication with the sensor; and the graphical user interface that displays the patient information. During a reading, the antenna is placed near the implant site and communicates with the sensor by way of a radiofrequency signal that is generated and processed by the main unit. The graphical user interface allows for system operation and data entry and displays information generated from the sensor. This information includes a pressure waveform and readings, such as mean arterial pressure, systolic and diastolic blood pressures, heart rate, and cardiac output.

By comparing pressure waveforms before and after deployment of the stent graft, the system assists the physician in confirming traditional angiographic findings of successful stent graft placement. During the endovascular repair procedure, pre- and postexclusion pressure measurements demonstrate the difference between an aneurysm sac that is exposed to circulation and one that is excluded.

The first application of the technology to be cleared by the FDA was for the measurement of intrasac pressure during endovascular abdominal aortic aneurysm (AAA) repair, serving as an adjunctive tool in the detection of intraoperative leaks of the stent graft. In March 2007, the same system (EndoSure Wireless AAA Pressure Measurement System) was cleared by the FDA for measuring intrasac pressure during thoracic aortic aneurysm repair. In December 2006, the wireless pressure sensor for heart failure monitoring was successfully implanted in 2 patients at Oklahoma Heart Hospital (Oklahoma City, Oklahoma).

Supported by an independent educational grant from Pfizer

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