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Medical Product Manufacturing News, September/October 2015

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M E D I C A L P R O D U C T M A N U F A C T U R I N G N E W S Q M E D . C O M / M P M N 1 4 S E P T E M B E R / O C T O B E R 2 0 1 5 The Makings of an Implantable MEMS Cardio Sensor The sensing technology at the heart of the CardioMEMS HF system was inspired by a MEMS sensor designed to monitor jet engine pressure. Brian Buntz SPECIAL FEATURE: CARDIOLOGY A s is the case with many large medical device makers, St. Jude Medical appears to be seeking to not only provide devices but a whole toolbox of products and services to treat a specif c chronic disease, in this case heart failure. The implantable CardioMEMS device is proving to be an especially important tool in its cardiovascular device arsenal. About the size of a paper clip, it uses MEMS technology to remotely monitor a heart failure patient's pulmonary artery pressure. Financial analysts have been upbeat about CardioMEMS technology, which was acquired by St. Jude Medical in 2014. The analyst firm Zacks states that the technology is expected to generate $70 million in sales in 2015. And a report from EvaluateMedtech recently stated that the technology helped push up St. Jude Medical's share price in the first quarter of the year, and could ultimately top $1 billion in peak sales. CardioMEMS's roots go back a decade, when Jay Yadav, MD, former director of vascular intervention at the Cleveland Clinic, had the idea of taking MEMS technology designed for jet engines, and using it inside the pulmonary artery. Both were tubes, after all. "They could ping the sensor with radio- frequency energy and measure the pressure inside of the tube," Philip B. Adamson, MD, medical director and vice president of medical affairs at St. Jude Medical, said of the technology, which was developed at Georgia Tech. Yadav went on to found CardioMEMS in 2000 to commercialize the idea. In 2005, Yadav reached out to Adamson and Bill Abraham, now the associate dean for clinical research at the Ohio State University Wexner Medical Center, and asked the two to design a trial of hemodynamic monitoring of heart failure patients using MEMS technology. When the two first heard about the technology, they were intrigued by the potential advantages of MEMS technology, which has a much smaller form factor than the can-type design traditionally used in cardiac rhythm management devices. (The current version of the device is roughly the size of a paper clip.) "We thought: 'gosh, it should survive the confines of a jet engine, it can survive the environment within the human body,' and sure enough it did," Adamson says. Years later, when it was time to test the product clinically, the product was associated with a 38% reduction in heart failure-related hospitalizations. Based on the study results from 2011, St. Jude medical estimates the product could potentially save the U.S. healthcare system more than $8 billion annually by reducing such hospitalizations. The device's small size is one key to its efficacy. "There are some unique technologies that were encompassed in this little wafer disk that is implanted permanently in the pulmonary artery. The secret to being able to do this with minimal risk and significant benefit," Adamson adds.CardioMEMS was ultimately acquired by St. Jude Medical in 2014 for $450 million—the same year it achieved FDA approval. Developing a Device for an Evolving Cardiology Philosophy For Adamson, who helped design the clinical trial for the device, the CardioMEMS device is a culmination of a changing philosophy that began to emerge in the mid-1990s in cardiology. About two decades ago, the notion of using hemodynamic monitoring to treat heart failure patients was just starting to take hold, he says. "One of the most important things in the heart failure disease management program is frequent assessment of the patient," Adamson says. "You hope that by doing that, you are going to catch things that would lead to hospitalization, and by catching them early, you proactively manage them and keep them from decompensating." But decades ago, frequent assessment meant seeing a patient at a weekly interval. "Because the vast majority of the patient's time is spent at home, we always felt there should be some way to monitor them there that would be better than having them report just their daily weight." In the 1990s, electrophysiologists were beginning to become prominent in the management of heart failure, Adamson recounts. They began to think about new applications of the data gathered by the cardiac rhythm management (CRM) devices they were implanting. "We thought we might be able to harness some of that information to get a better handle on how patients with heart failure were doing," explains Adamson, who in 1995 founded the Heart Failure Treatment Program at the University of Oklahoma. He went on to found the Heart Failure and Pulmonary Hypertension Treatment Institute at Oklahoma Heart Hospital in 2005. Device makers tried leveraging CRM technologies to monitor aortic pressure in the late 1990s and early 2000s in clinical trials. In a number of trials, Medtronic tested combined cardiac resynchronization and implantable cardioversion defibrillation in their Chronicle device, which was an ICD that had the ability to monitor the pressure inside the heart as well as body temperature, patient activity, and heart rate. Adamson was the principal investigator of Medtronic's Reduce HF trial, which coupled the Chronicle device with a single chamber defibrillator. "Launched in 2006, that trial ended because that technology was kind of old and lead-based and pacemaker-like," he says. "All of the things that went with pacemakers went with that: lead dislodgement, pocket infections, and all of that stuff. Because the technology was less than optimal, the sponsor decided to abandon that project." Enter MEMS technology, which could theoretically monitor aortic pressure without leads or even a battery. But its clinical benefit was then unproven. At roughly the same time Medtronic was abandoning their Reduce HF trial, Yadav reached out to Adamson to help design a clinical trial for the MEMS technology, which ultimately persuaded FDA reviewers of its safety and efficacy. The benefits of the MEMS technology were considerable. "The risks of implantation are incredibly low. You don't have to replace the battery, you don't have to replace the device, and it lasts as long as the patient," Adamson says. "When you have the tremendous benefit that we found in the Champion trial, it really makes it pretty easy to accept as a technology to change the way we do things." The Challenge of Proving Clinical Utility It was initially difficult, however, to prove to FDA that the benefits of such a novel device

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