Miniaturized, leadless pacemakers are one of the most innovative cardiac devices to recently get implanted into human beings.
So how were medical device companies able to get the pacemakers small enough to implant directly inside the heart using a catheter?
In the case of Milpitas, CA-based Nanostim, acquired by St. Jude Medical this year for $123.5 million, better device communications played a major role in the miniaturization, according to Drew Hoffmann, the former Nanostim CEO who is now senior vice president and general manager of Nanostim at St. Jude.
Hoffmann's comments contrast with what Mark Phelps, senior program director, diagnostics and monitoring at Medtronic, says about the development of Medtronic's Micra, roughy a third smaller than Nanostim's pacemaker. Phelps says Medtronic had to concentrate on everything in order to make the Micra tiny because, "everything is connected to everything else."
Hoffmann, however, points to a key breakthrough in communications that brought Nanostim to a point where it has a European Union-approved pacemaker that does not need the wires, called leads by the designers, that have plagued such devices so much in the past.
By communications, Hoffmann means the ability to download information from the pacemaker and program it.
"I think the key thing we figured out was how to do communication with very low power. That is different from the general improvement in miniaturization of integrated circuits and batteries, etc. We have a very low power communication scheme that allows us to have fewer components and more compact components," Hoffmann says of the device, which won European Union approval this year.
|"I think our proprietary communication scheme and also the growing acceptance of catheters to do procedures in the heart involving devices like valves has opened the door to our approach," Drew Hoffmann, senior vice president and general manager of Nanostim at St. Jude, says of the company's tiny leadless pacemaker.|
So how did Nanostim achieve low-power communication?
"Our communication is conducted communication. It's kind of the way you measure an EKG. You measure the very strong signals emanating from a patient's heart to the surface of their body, with electrodes on the outside," Hoffmann says.
Medtronic took a more unusual approach to developing the Micra because it was a systematic, in-house effort. St. Jude meanwhile took a more usual approach of acquiring a younger company, Nanostim (run by Hoffmann, a former St. Jude executive), that had innovation technology. It will be fascinating to see which pacemaker turns out to be the better device in the long-run.
Hoffmann had plenty more to tell MPMN about the advances Nanostim was able to accomplish with its device. Here's more of what he said:
MPMN: What kind of functionality are you able to pack into the space?
Hoffmann: It does everything a conventional pacemaker does. I interviewed a lot of patients and clinicians at the beginning of the project to figure out what kind of features we had to provide to be a competitive adoptable product. Patients like their pacemakers because they feel so much better after they've gotten one, and they've told me, "I love my pacemaker, and I don't want to give up any of the function it has." And when I tell them what our pacemaker [does], ... and their response is, "Wow, I don't have to have surgery." It's put in with a catheter. And they say, "You mean I won't have a lump under my skin and my leads won't break?" They say, "If you could do those things and it does everything my pacemaker does, we'd really want that."
MPMN: What is everything?
Hoffmann: It's constantly listening to the heart and constantly providing stimulation to the heart to make sure the heart is beating as needed. It has a thing called rate response where it can sense when the patient's level of activity is increasing, and when it senses that, it speeds up the amount of stimulation so that it makes the heart beat faster to give them the oxygen, the profusion that they need. It stores data about the patient that can be retrieved at follow-up by interrogating the device.
MPMN: With the energy you need, how long does the battery last?
Hoffmann: This is a self-contained device that ... doesn't get recharged by an external device. It is freestanding, if you will. One of the things we learned when we talked to patients and doctors was they need to have the longevity. The device has to last as long as their current devices do. Say you're pacing about half the time, which is not unusual for a pacemaker patient, the device will last about 13 years. That's about as long or longer than a conventional pacemaker.
MPMN: How hard would it be to remove it after 13 years, or do you just shoot in a second one and not worry about the old one?
Hoffmann: That's a really important question. When we were doing our upstream market research, we asked people that. Some people said they'd rather we'd live it in and put in another device next to it. Half the clinicians said, "I'd like to be able to remove it." ... If there's something wrong, we need to take it out, and it needs to be done without open heart surgery. We decided it had to be retrieved using a catheter-based procedure. We have that. We've shown we can put devices in, turn off an existing device, put in another one next to it. But we've done a lot of work to show that with our retrieval system we can retrieve our device that's been implanted.
MPMN: The Micra is titanium-encased. Is your device titanium encased?
Hoffmann: It's a biocompatable metal. I think I'd be be happy saying that now. ... We're not using any exotic material. We're using known biocompatable materials.
MPMN: The big advantage is no more leads, right?
Hoffmann: A big advantage is it doesn't have a lead, so you don't have the lead complications. And the other advantage is that with a conventional pacemaker, the can, if you will, is put in a pocket that's formed under the skin of the patient. There are complications that can occur ... can get infected. You can have hematoma, excessive bleeding. You can have erosion. Some patients play with the device after it's healed. They'll spin it around, which is known as twiddler's syndrome. That tangles up the lead. Eliminating the lead and eliminating the pocket are the big advantages of this.
MPMN: How is it designed to make it easy for the implanting physicians?
Hoffmann: We put a lot of working into making the implanting procedure something that would be very familiar to cardiologists and electrophysiologists. It's a catheter-based procedure. And we made a catheter that is very easy to use, that's able to be inserted into the femoral vein and then navigated into the heart, into the right ventricle. And we have a number of features that give clinician flexibility in terms of where they put it in the heart and the ability to verify that it's working before they release it from the catheter.
MPMN: Anything else to sum up what kind of technological breakthroughs enabled you to do this now, to overcome challenges
Hoffmann: I think our proprietary communication scheme and also the growing acceptance of catheters to do procedures in the heart involving devices like valves has opened the door to our approach.