Originally Published MDDI August 2005
As cardiovascular technologies and the devices that incorporate them continue to improve, heart patients have a host of new options for treatment.
|Medtronic's InSync Sentry ICD
automatically monitors fluid status in the thoracic cavity, helping
doctors predict worsening heart failure.
Cardiovascular care has been revolutionized in the past few years, and medical devices have had no small part in that. Ten years ago, no one had even conceived of technologies such as implantable defibrillators, ventricular assist devices, and stents that deliver a drug in addition to keeping an artery open. Such advances have made the cardiovascular sector the fastest-growing and most watched segment of the device industry. More importantly, these advances have enabled patients with severe heart problems not only to recover, but also to resume relatively normal lives.
The innovations of 10–20 years ago may have enabled patients to keep living, but the innovations of recent years have allowed patients to resume a high quality of life. What is the next step? It appears that the next wave of innovations will focus on monitoring. A number of companies are developing devices, many of them implantable, that alert clinicians immediately when a patient is having a heart problem or even showing signs that a problem could be on the horizon.
The process of heart surgery and even the purpose of implanted devices may evolve, too. Much progress has been made in developing minimally invasive procedures that reduce patient trauma and hospital stays. These techniques should get further refined in the coming years. And more emphasis is likely to be given to devices being used as delivery systems for drugs, biologics, and other therapeutic agents.
What developments are making these things happen? Here is a sampling.
Changing the Pace of Heart Care
Implantable defibrillators and similar devices are changing the way clinicians think about heart care. These technologies are providing the day-to-day data that enable them to take a more-active role in their patients' cardiac care—in many cases, without even having to see the patients in person. Defibrillators have also helped shift focus to preventive care.
“Three years ago, we put in more pacemakers than defibrillators. Two years ago, it was about even. In the past year, we've put in defibrillators about three-quarters of the time,” says Bruce Wilkoff, MD, director of cardiac pacing and tachyarrhythmia devices at the Cleveland Clinic Foundation (Cleveland). “The improvement in defibrillators has profoundly affected us. We can now use them to protect against slow heart rhythms and arrhythmia-related deaths. Often, we will apply them for biventricular pacing as well. And that progress is based on the technology.”
A lot of the progress is owing to advances in sensors that enable improved monitoring and data collection.
|Advanced sensors in heart-assist devices enable improved monitoring and data collection. Photo courtesy of AMI Semiconductor.|
“Within implantable cardiac rhythm management devices, the next plane of innovation is additional ways to provide sensor-augmented therapy,” says Michael Rice, medical marketing and business development manager for AMI Semiconductor Inc. (Pocatello, ID). “These are patient-specific sensors that can track changes in real time. Within the pressure management arena, a lot of good is being done with this. It can enable you to customize the properties of the implant, change them on the fly, or adjust doses of medications.”
This has not only improved the quality of cardiovascular care, but also has potential for cost-effectiveness. And that has had a favorable effect on reimbursement. “There has been a dramatic change in the level of data available for analysis of technologies such as defibrillators,” says Wilkoff. “That has produced a number of fruitful clinical trials and affected the reimbursement environment. It has changed profoundly the way we practice arrhythmia therapy. It allows us to put in defibrillators in nonischemic patients for primary prevention. And we are still able to reduce total mortality. Prior to that, a patient had to have had cardiac arrest or coronary artery disease [to receive a defibrillator].”
A watershed moment was the completion of the SCD-HeFT trial, which showed that implantable cardioverter-defibrillators (ICDs) reduce death from heart failure by 23%. That finding prompted the Centers for Medicare and Medicaid Services (Baltimore) to increase reimbursement for ICDs.
Sensors and Algorithms
“Not only have there been significant advances in devices, but also in leads and implant tools,” says Wilkoff. “The use of sensors has been very valuable. We can now measure all sorts of intracardiac pressures. Everybody is moving toward collecting more information—and not just to have it, but to do something with it. Remote monitoring may be the most important technology in that regard. We can install these devices in people's homes and monitor their clinical status from there. In our system, the data come through the Internet and make it all the way to the electronic medical record. We are definitely ahead of the curve on this, but it's coming.”
Several companies, Rice says, are at the forefront of this movement, including Medtronic Inc. (Minneapolis). Its InSync Sentry ICD provides cardiac resynchronization. When approved in November 2004, it became the world's first device to automatically monitor fluid status in the thoracic cavity. Thoracic fluid accumulation is a significant indicator of worsening heart failure, so the device can help doctors predict when a patient will need to be hospitalized, rather than wait for a catastrophe.
Another firm using implantable devices for monitoring is Transoma Medical (St. Paul, MN), whose LVP-1000 product monitors left ventricular pressure. It has an extremely stable sensor that cuts down on pressure drift over extended periods of time.
Patients with other cardiovascular conditions are expected to benefit from remote monitoring soon. For example, CVRx Inc. (Maple Grove, MN) is developing an implantable device, the Rheos, to treat hypertension. When it senses a rise in blood pressure, it sends a signal to the central nervous system. The signal prompts the brain to dilate blood vessels and improve blood flow.
|The stable sensor in Transoma's implantable devices cuts down on pressure drift over extended periods of time.|
Likewise, CardioMEMS Inc. (Atlanta) is developing an implant to monitor aneurysm sac pressure in patients with abdominal aortic aneurysms. Until recently, major surgery was required to fix the condition. Now a less-invasive procedure called a stent graft is used to strengthen the aortal wall. The device is implanted during the stent-graft surgery. It measures the pressure of the aneurysm sac and alerts clinicians if the sac is in danger of rupturing.
Similar advances in sensing can be seen on external products. One, from CardioNet (San Diego), consists of a small sensor worn as a pendant or on a belt clip. It records two channels of ECG and communicates findings to a small monitor stored in the patient's pocket or purse. When the monitor detects arrhythmia, it sends the results to a service center. The people at the center analyze the data and report them to the patient's physician.
“The sensing technologies that drive products like these have a bright future,” says Rice, who worked for several device companies before joining AMI. “A lot of the biocompatibility issues related to them may be solved in the next couple of years, and then they could really take off.”
Advances in algorithms are also contributing to improved cardiovascular device technologies. One such device is the Atlas+ HF ICD from St. Jude Medical Inc. (St. Paul, MN). It has an algorithm that enables programmable timing of the left and right ventricular outputs. That allows clinicians to choose which ventricle to pace first and to decide how much of a delay is needed for the second ventricle. This can help patients who don't respond to simultaneous biventricular pacing.
Another case of innovative algorithms is the Audicor technology from Inovise Medical (Newberg, OR). It detects myocardial infarction, left ventricular hypertrophy, and other heart conditions in patients with nontraditional symptoms. It then integrates those findings into a standard ECG. Part of the system involves microphones to improve detection of abnormal heart sounds. The Audicor won a Medical Design Excellence Award in 2004.
But for sensor and remote monitoring technologies to be used to their full potential, a system must optimize tracking and follow-up. That's also in the works, says Wilkoff.
“We had been implanting hundreds of defibrillators a year, and now we do more than 1000,” he says. “Every year, the biggest problem is following all of the changes to all of the patients. Nobody could sustain that kind of growth with the old systems. We have to be able to manage it. Only the use of electronic medical records and remote monitoring can handle it. So we've had to change our whole system. You need a comprehensive patient management system and devices with sensors and long-distance telemetry. This allows comprehensive monitoring without being invasive to the patients' lives. It will take time to work out the kinks and for patients to get used to it. People do things the way they're used to doing them. But not having to go to the hospital for follow-up could make a huge difference in quality of life.”
|When CardioNet's external sensing monitor detects arrhythmia, the results get relayed to the patient's physician.|
Much has been written about the effect of drug-eluting stents on coronary artery disease. The two FDA-approved products, Cypher from Johnson & Johnson's Cordis Corp. (Miami) and Taxus from Boston Scientific Corp. (Natick, MA), reduce restenosis dramatically compared with bare-metal stents. With fewer patients needing a second intervention because of reblocked arteries, improvements in quality of life and long-term cost reductions have been dramatic.
But what's next on the stent development front? New designs could extend the reach of the treatment into patients previously considered too at-risk for the procedure. However, it's not clear when that will happen, or how significant the effect will be.
Thomas Gunderson, managing director and senior research analyst for Piper Jaffray (Minneapolis), sees slow growth in stent use, with drug-eluting stents going only to patients who would have received bare-metal stents in past times. Because the technology hasn't been around long, “it's been hard to get clinical data to show that it's an improvement” over anything other than bare-metal stents, he says. “It will take a long time to get more-definitive data out.”
Stents should continue to play a major role in cardiovascular treatment. But how they are used and the kinds of patients they are used in could evolve in the future.
“We are now investing in making drug-eluting stents reduce or eliminate the onset of thrombosis,” says Bruce Barclay, CEO of SurModics Inc. (Eden Prairie, MN), which developed the coating for Cypher. “It does not happen often, but when [thrombosis occurs], it can be catastrophic. So much work is going in to putting an antithrombotic agent on the stent. If you can eliminate or reduce the clots that form on the stent until it becomes endothelialized, then you ought to be able to reduce the onset of thrombus going forward. So that's an active area of interest.”
Michael Drues, PhD, president of Vascular Sciences (North Grafton, MA), sees more-radical applications down the road.
“The current drug-eluting stents are a stepping stone to better products in the future,” he says. “I can see the day when they evolve into multiple combination products. There could be a stent with multiple drugs and multiple biologics, all of which are designed to do different things. And if you look further down the road, the real future is tissue engineering. We will be able to do things we can't even dream of now to fix problems in the arteries and throughout the body. The whole function of medical devices will change. We might be able to use tissue-engineering biological products to encourage injured cells to regrow—and use a medical device to deliver the therapeutic to do that. Instead of delivering a stent into an artery to hold it open, we could use it as a local drug-delivery or biologic-delivery system. Most diseases are characterized by a loss of function. Medical devices alone don't restore function. But combined with other things, they can be used to help restore function, and possibly to treat some of the most insidious diseases affecting our society today, including diabetes, Alzheimer's, Parkinson's, and multiple sclerosis. Some may ask, ‘Does this mean we will be using fewer devices in the future?' On the contrary, I believe we will be using many more devices in the future than we do today; however, we will be using them in drastically different ways. In short, we must think biology, not just mechanics.”
These visions of more-complex implantable devices are giving rise to improvements in other areas.
One research goal is to design technologies that simplify and improve the less-invasive procedures that have come into vogue. For example, Access Scientific Inc. (New York City) is developing products to be used in a procedure that would replace the Seldinger technique. For 30 years, the Seldinger technique has been the standard method to deliver balloons, stents, chemotherapy drug infusions, and the like. Access Scientific's product would create a smaller access point, which would be less traumatic for the patient, says Janelle Anderson, general manager of Access. “It gives doctors the ability to go with a smaller needle, regardless of the size of the sheath,” she says. “It's a micropuncture.”
Research has also focused on the manufacturing of and material selection for catheters, guidewires, and other technologies that assist cardiologists and cardiac surgeons.
“We are seeing a significant increase in demand for components that facilitate less-invasive cardiovascular procedures of increased complexity,” says Ron Lowell, director of sales and marketing for Upchurch Medical (Oak Harbor, WA). “We are designing and manufacturing catheters in a wide variety of materials and configurations to serve as the conduit for intravascular therapeutic and diagnostic procedures. Things are not as simple as they used to be, and the challenges must be met through higher-performance materials and processing. Extrusion, molding, machining, and assembly of biocompatible materials like PEEK and other high-end engineering thermoplastics are now required.”
Thanks to improvements in medical devices, the cardiovascular care of today looks nothing like it did 10 years ago. With all the advances being made right now, and others in development that show great potential, it's more than reasonable to expect that the cardiovascular care of 10 years from now will look nothing like it does today. As with all progress, there will be false starts and adoption issues, but once those are overcome, patients with heart or coronary artery problems will be in better position to enjoy a long life span than ever before.
Copyright ©2005 Medical Device & Diagnostic Industry