The design and development of a continuous intravascular monitoring stent

Brooke Leigh Beier, Purdue University

Abstract

Continuous intravascular monitoring of blood pressure and glucose levels from a minimally invasive device can serve as a diagnostic and early-warning system for cardiac health and as a valuable disease management tool for diabetics. Heart failure (HF) is the number one cause of death among men and women in the developed world, affecting approximately 2 % of the adult population and 6-10 % of people over the age of 65. Catheterization of the right heart is routinely used to obtain the pulmonary pressures and cardiac output data in patients with severe heart failure in the acute setting. The invasive nature of the procedure and lack of a portable monitoring device has limited its application to chronic heart failure patients at the bedside and in the ambulatory setting. As a result, there is a need for a minimally invasive device that can continuously monitor pulmonary pressure without limiting a patient to a hospital setting. A link has been discovered between heart failure and diabetes, as the prevalence of diabetes in heart failure populations is close to 20 % compared with 4 to 6 % in control populations. Approximately 180,000 Americans die from diabetes each year and it is predicted that 366 million people will be affected worldwide in 2030. Continuous monitoring and tight control of blood glucose levels decreases the occurrence and severity of long-term complications associated with diabetes, but available devices suffer from patient non-compliance, limited device lifetime, and the time lag between the measured interstitial fluid glucose levels and blood glucose levels. A novel platform technology that piggybacks on an FDA-approved stent to support transcutaneous wireless telemetry of measurements taken from within the circulatory system has been developed. For blood pressure monitoring, the device is a miniaturized system, consisting of an application-specific integrated circuit and a MEMS pressure sensor, attached to the outer surface of a regular or drug-eluting stent. The same platform is explored for use as a continuous glucose monitoring system by incorporating a glucose-sensitive hydrogel, whose volume changes as a function of glucose concentration, into a MEMS sensor. One of the largest barriers in front of the development of such a miniaturized implantable device is the ability to reliably power the device post-implantation for the lifetime of the patient. Today, most electronic implantable devices, such as pacemakers, contain large onboard batteries that require surgery for replacement. To reduce size and eliminate the need for additional surgeries, the use of the stent as an antenna to wirelessly couple power from an external source to the device is evaluated. When expanded, the stent maintains a patent vessel lumen while allowing contact between the electronic sensors and the blood supply. Using the stent platform takes advantage of an FDA-approved device whose safety and surgical deployment procedures are well established. This work optimizes the RF-powering for the device, explores the packaging and deployment of the device, presents an algorithm to extract valuable parameters from a blood pressure waveform, and proposes a platform for a continuous glucose monitoring system.

Degree

Ph.D.

Advisors

Irazoqui, Purdue University.

Subject Area

Biomedical engineering|Electromagnetics

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