Exploring Mechanical Circulatory Support and the BiVACOR Total Artificial Heart

On this episode of Inside the Texas Heart Institute Studio, Dr. Joseph G. Rogers sits down with Dr. William E. Cohn to discuss the latest advancements in mechanical circulatory support and the development of the BiVACOR Total Artificial Heart (TAH). Dr. Cohn, a leading expert in the field, sheds light on the potential benefits of the BiVACOR TAH for patients with severe heart failure.

The conversation explores:

• Limitations of current ventricular assist devices (LVADs)
• Patient populations that might benefit most from a TAH
• Potential applications of the BiVACOR TAH as a bridge to transplant or destination therapy
• The unique design features of the BiVACOR TAH and how it balances circulation
• The future of TAH technology and its potential impact on heart failure management

This episode offers valuable insights for healthcare professionals, patients with heart failure, and anyone interested in the future of cardiac care.

For more information on the BiVACOR Total Artificial Heart (TAH) visit texasheart.org/tag/bivacor

🔗Watch the Studio Interview on Texas Heart TV

🔗 Watch Dr. Cohn’s Grand Rounds

Disclaimer:
The views and opinions expressed by Inside the Studio guests do not necessarily reflect the views or positions of The Texas Heart Institute.
Disclosure:
The Texas Heart Institute has an equity ownership interest in BiVACOR.

Watch On Demand Videos on Texas Heart TV

Visit Our Website: texasheart.org

Chapters

• 0:36 Limitations of Current Treatments and Who Can Benefit from a TAH
• 2:20 Bridge to Transplant vs. Destination Therapy
• 5:33 Unveiling the BiVACOR TAH's Design
• 11:08 The potential impact of the BiVACOR TAH

Transcript

0:00

Hi, I'm Dr. Joe Rogers, president and CEO of the Texas Heart Institute, and I'm joined here in the studio today by Dr. Billy Cohen, who has just given a terrific grand rounds on the history and the future of mechanical circulatory support, particularly focused on the development of the total artificial heart. Billy, thanks for joining us to spend a few minutes just sort of expanding on the comments that you made during grand rounds today. Well, thanks for having me. You know, I'm really passionate about, uh, the whole field. I love talking about it. In fact, my wife got me a T-shirt that said Help. I'm talking and I can't shut up, so I'm, I'm delighted to Be here. Well, we're really happy to have you and it's great to have you back at, at T-H-I-I-I thought that, um, I'd like to just spend a little bit of time thinking with you about the patient populations that might be most, uh, or might be best served by a total artificial heart, and then think about how that could potentially evolve, uh, as we, as we we're able to demonstrate the efficacy of the therapy. And I think you highlighted the real important challenges with the currently available devices and the devices that have come in and out of clinical trials. But, but the biocore pump seems like it has some real potential advantages relative to those older pumps, including durability. And so wouldn't mind if you wouldn't, if you could expand on that, it'd be great. Sure. I mean, exactly what you said. We think there is a, a large population of patients that are poorly served by what's out there now, specifically patients with severe irreversible biventricular failure, and we can transplant them, but they're not all transplant candidates and even those that are transplant candidates, bridging them till we can find an acceptable donor organ, there's nothing that really works well. And, uh, so the way we've crafted with the FDA, this first, uh, EFS trial, early feasibility study that we're doing, we're gonna take patients that are transplant candidates, put the device in, bridge them to transplant, just to show that we're in the ballpark. And for all the reasons you just said, we think they're, uh, it's quite possible that this is a, uh, maybe the best technology for those patients. One moving part magnetic levitation, so there's no mechanical wear, provides great flow, really low filling pressures, easy to put in. We'll see, that's what the EFS study's designed to Look at. What are you guys thinking about now in terms of the pivotal trial? Uh, are you thinking it's really still gonna be tested as a bridge to transplant? Are you gonna take more of a momentum three kind of approach where you're gonna look at a short term cohort and a longer term cohort? Exactly. Correct. That kind of align with bridge to transplant or destination therapy? What, what, what, what does that look like? Exactly what you just said, short and long term. And we think the opportunity for a technology like this is for patients that aren't transplant candidates. We think of destination therapy, uh, for, for the, uh, 150, 160,000 Americans that die every year of severe biventricular heart failure. And so if we had something we could take off the shelf, no, uh, Lear Jets and helicopters in the middle of the night after a team has been operating all day. Uh, but an elective procedure with a fresh team and a off the shelf device, we think that's gonna be transformative for the management of heart failure. And in terms of the relative advantages, so here's what I wanna explore with you for just a minute. A patient who is eligible for LVAD, can you imagine that those patients might be better served with a TAH kind of approach? And I'm, I guess what I want to sort of pick your brain about is, you know, we're seeing a lot of late heart failure in clinical trials and in registries after LVAD mm-Hmm. And it's not entirely clear whether that's left ventricular failure from not running the pump correctly, or whether we're not getting sufficient unloading of the left ventricle by the LVA DS or whether we're seeing late right. Heart failure. And it's probably, the reality is it's a combination of both combination. Yeah. So, And progressive aortic insufficiency and Yeah. So all that, some patients are incredibly well-served by LVA ds, uh, um, uh, there's a patient out in, uh, that Walt Demsky has in San Diego who's had a single HeartMate two for 19 years. But a lot of patients, maybe as many as a third, some people say 10%, I think it's closer to a third, never get restoration of exercise tolerance because of Right. Heart reserve. And as you just said, even when we unload them, there is a deterioration, no question about it. And, uh, for a variety of reasons, it's possible. It's possible that replacing the whole heart might be the answer to all that. We'll have to see. Uh, I can tell you, uh, we've done at the Texas Heart Institute, the GLP Good Lab practice, uh, studies for a lot of these pumps, including the HeartMate three, it was all done at the Texas Heart Institute. Texas Heart Institute has played just a, a, a a, a fundamental role in the development of this field and all the BiVACOR studies as well. But, uh, um, I can tell you that the way these animals go after a BiVACOR implant is in, they are standing an hour or two after surgery and get immediately extubated. Uh, we've never seen an artificial heart like that. Can an artificial heart ever compete with an LVAD? The right one can. Is this the right one? We'll see. Yeah. The other thing, I think it would be interesting for you to talk about a little bit more, and, and you and I have had conversations about how the pump balances circulation and, and, and, and I, I wonder if you wouldn't mind walking us through that again. Sure. 'cause it's, it's complicated. You've got one spinning rotor and, and, and, and you've, I think, highlighted the, the different kind of design on each side of the rotor for the right and the left. But maybe you could talk a little bit more about how that rotor's actually bouncing the pulmonary and the, and the systemic circulation. Absolutely. And that's the fundamental brilliance of the technology. That's something that Daniel Tims conceived of during his PhD thesis. It would nick great tricks and Mattea Klein higher, uh, were able to distill to practice. So you have one disc spinning in an electromagnetic field, so it's not touching anything. And that's not new. The HeartMate three does that. There are other devices out there that do that. So it's spinning around and on one surface is a very flat pinwheel looking, uh, impeller. And on the other surface is this big thing that looks like Stonehenge, a bunch of blades sticking up. Why so different? Well, because your pulmonary circulation is so different from your systemic, uh, circulation as far as resistance, but they both have to flow about the same Mm-Hmm. And now, since they're co-located on a single rotating element, they have to turn at the same speed. So figuring out what the geometry of those two, uh, elements had to be was not a trivial task and just brilliantly performed by the Bible court team under Daniel, uh, Tim's leadership. But it's more subtle than that. The, uh, impeller as it's floating in this space in the vol, the inflows and outflows, it can translate, it can move a little to the left. It can move a little to the right. And when I say a little, the whole magnitude of motion is 700 microns, about three fourths of a millimeter. And you think, well, why would that matter? It turns out that left pinwheel, if it is 10 microns or 20 microns away from a flat surface, it's a ferocious pump. Mm-Hmm. If you move it 700 microns away from it, it's less ferocious. It's constantly deciding how aggressive does the left pump need to be for what the pulmonary vascular resistance is right now for what the systemic vascular resistance is right now. And you and I, our pulmonary vascular resistance is changing every three or four seconds when we inhale and exhale, when we exercise, when we cough, when we strain to go to the bathroom, sensors are seen exactly where the rotor is 20,000 times a second. And communicating that to the controller that looks at the last fraction of a second and a thousand times a second, maybe 2000 times a second, repositions the rotor for what's going on at that instant. So it reacts much faster than a sneeze. Mm-Hmm. Much faster than a cough. And we see that in the animals as they're on the treadmill, they'll cough and the rotor will immediately move. I mean, it's like magic. I, I mean, it's actually, I agree. It's the brilliance of this pump is that it's actually becoming a smart pump, which, which many of us have have advocated for in the LVA space, which, uh, they're, they're very simple di device devices. And I think that some of the exercise limitations that our patients experience are re are, are as a result of Right. The pump not responding to physiologic demand. Exactly. And I, and my sense is in having done this with you now downstairs with, uh, you know, with some of the animals, the, those, the cows actually increase their cardiac output fairly significantly when they start to Walk substantially. And we've seen cows, uh, walking at a brisk rate on a motorized treadmill and have their cardiac output be, uh, 11, 11 and a half liters when they were lying down. And they get up and start walking. It goes up to 1920 liters a minute. Yeah. Yeah. So autonomy is a great thing. The another brilliant design feature is, um, there's been some enthusiasm for patients with severe bi biventricular failure to put two LVA Ds Mm-Hmm. One in the left and one sort of, uh, rigged to perform on the right. All the LVA Ds are very clot intolerant. Mm-Hmm. If you take thrombus and throw a little in them, they will fail. They'll, uh, and it's a common, uh, waterloo for patients that have a, a durable pump on the right. Uh, when we all, when we sit down and watch the planet of the Apes marathon and get up to go get an orange juice, we liberate clot from our veins. How do we know autopsies And people that have died in wars, young healthy people, they all have little pulmonary infarcts. You can't have clot going through one of these rotary pumps. The impeller on the BiVACOR looks more like the paddle wheel on a riverboat. The reason they made riverboats that way is because rivers have submerged bushes and sand dunes, and you can't foul a paddle wheel. You can't foul the right rotor. We've in flow loops thrown clot into it, and it'll whip it around and then throw to the pulmonary, uh, artery Mm-Hmm. And keep pumping. So there are so many features about this pump and the shunt over the outside of the rotor to keep it clean. Uh, the cyclic modulation of speed to make a pulse once a minute, dropping it to let backwards flow go, to keep the pump clean. Uh, in the last five animals, uh, we submitted to the FDA, they weren't on coumadin, aspirin, or any type of anticoagulants. So this was the last thing I wanted to talk to you about. And, and, uh, and that is what in the human trials, what are you thinking now about anticoagulation? Antiplatelet therapy? Therapy certainly has been an achilles heel for much of the LVAD, uh, technology and, you know, the recent Aries trial demonstrating that, um, maybe aspirin is less important than we thought it was. Correct. Yeah. With some of these newer generation maglev technologies. Tell us, what, what are you thinking about, um, anticoagulation antiplatelet therapy? Yeah, For our first, uh, these first five, we're gonna do what industry standard is with, with the new understanding of the non importance of aspirin. But, and we're gonna get tags and INR and, and manage that in platelet counts and manage them just like an LVAD. But it should be more tolerant than an LVAD, I think for the reasons we just described. Certainly on the right. Much more tolerant than anything we've ever put on the right for thrombus. And as we learn, uh, maybe there'll be an opportunity to back off on that. One of the things that we're keenly interested in is, uh, gastrointestinal hemorrhage. Yeah. Seems to be associated with lack of puls totality and the acquired von Willebrand syndrome, and some of the dynamics of how the molecule unfolds and things. And we have some people that are, uh, domain experts in that field. We've taken animals and sent their blood, uh, to to, yeah. To the various Von Willand assays. And there seems to be a very favorable signal. We'll see, we're making a pulse. We have wide gaps. You know, the HeartMate three, which is now the industry standard, beautiful, beautiful pump. And you talk about not being adaptive, the HeartMate four that Kevin Bork has shared with us some of the details Mm-Hmm. They're gonna put the MEMS device in it and have some sort of adaptive, uh, uh, uh, functionality. Yeah. Which is great that ABT is continuing to develop that technology. And that's wonderful for patients. It's wonderful for the field. Um, but, uh, the, the way the, uh, von Willebrand factor is broken down is high shear. High shear is a lot of different flow through a small gap. The HeartMate three has the biggest gap of any pump. It's 500 microns, one half of a millimeter, the BiVACOR, it's four millimeters over here, up to eight millimeters over here. Huge gaps. So the fact that our acquire von Willebrand profile seems to be very favorable. We'll see. Yeah. But, but that's, it's science. We'll figure it out. I think you and I probably could sit and talk about this for the next hour or two, but I think we probably should stop at this point. I, again, greatly appreciate you taking the time to the opportunity, come and spend with us, uh, talking about the pumps. Thanks very much for joining us here in the studio, Dr. Joe Rogers with Dr. Billy Cone. Thanks. Thank you.