Q&A: New class of total artificial heart implanted successfully for first time
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Key takeaways:
- The first implant of a novel total artificial heart was successfully completed at The Texas Heart Institute.
- The device fulfilled its role in serving as a bridge to transplant.
The first implantation of a new class of total artificial heart, a rotary pump with a single moving part, was successfully completed by a team at The Texas Heart Institute, the institution reported.
As part of an FDA early feasibility study, the device (BiVacor Total Artificial Heart) was implanted in a 57-year-old man with biventricular heart failure and cardiogenic shock who clinicians were unable to stabilize despite multiple therapies.
The total artificial heart replaced both ventricles and successfully served as a bridge to transplant, which occurred 8 days later. The patient celebrated his 58th birthday later in the month while he continues to recover in the hospital.
Healio spoke with Joseph G. Rogers, MD, president and CEO of The Texas Heart Institute and national principal investigator on the present total artificial heart research, about this novel device, the procedure and the patient’s recovery.
Healio: What was your involvement with the development and testing of this total artificial heart?
Rogers: The BiVacor Development Program has been at the Texas Heart Institute for 12 years. During those 12 years, we worked with BiVacor, particularly with BiVacor’s founder and chief technology officer, Daniel Timms, PhD, to refine the device and test it in a series of in vitro and in vivo experiments to get to the point that we were ready to implant the first patient here at the hospital.
Healio: Can you provide background about this implant and how it functions?
Rogers: I want to distinguish a couple of things. Most of the devices that are available for patients with HF support only the left ventricle. They are inserted in the apex of the left ventricle, draw blood from that chamber, and pump the blood back up to the aorta. They are left ventricular assist devices.
There is only one approved total artificial heart in the United States right now (SynCardia), and that device has been on the market for years. It’s a pulsatile device, so it functions like the native heart. It fills with blood; it’s actuated by a pneumatic driver that squeezes the bladders that contain the blood and pumps the blood out. That device is complicated. There are a lot of moving parts, and it has valves. Because it’s a complex machine, the durability is limited.
[Editor’s Note: On August 12, 2024, SynCardia emailed the following statement to Healio: “SynCardia has had a patient on the [SynCardia Total Artificial Heart] for over 5 years, showcasing its durability.”]
The novelty of the BiVacor [Total Artificial Heart] is that it replaces both ventricles of the heart and has only one moving part, a rotor that is suspended in a strong electromagnet. That rotor has no physical contact points because it is suspended perfectly inside the casing. As a result, there’s nothing to wear and there are no valves. We think that this will be a superior and durable device relative to predicate technology.
Healio: Could there be an increased risk for stroke as was seen with the SynCardia device, and how does this device compare with the Aeson total artificial heart, also in early feasibility study?
Rogers: Both of those devices are pulsatile devices. The technology here is completely different.
The fundamental difference is this idea that the BiVacor heart is a continuous flow device, where the other devices are pulsatile.
The engineers have been able been able to develop an artificial pulse by spinning that rotor at different speeds, so we can create a pulse pressure not dissimilar from the native heart. Alternatively, it can be run as a perfectly continuous flow pump where there’s no variability in BP.
Regarding stroke risk, the advantage that we perceive with this device is that there are no valves. Those are always the potential source for stroke, but the gaps inside the pump are very wide. So. the blood flow patterns inside the device are favorable and decrease the risk of forming clots.
In addition to that, the rotor speed slows down once per minute and then speeds up, which increases the washing on the inside of the pump. We believe that the stroke risk with this device will be very low.
Healio: What made this patient the ideal candidate for the total artificial heart implant?
Rogers: This patient was a 57-year-old man. He had been waiting for a heart transplant with severe biventricular HF. At the time we screened him for the study, he was being supported with a temporary catheter-based ventricular assist device and two intravenous medicines. Despite all of that, he was not stable. He was still in cardiogenic shock and was feeling poorly. We didn’t know how long it was going to take to find an organ for him in that condition. He was a good size fit for the device, and he is courageous man. We spent a lot of time explaining to him what we had done to get the device to the point where we were ready to implant it in a human, and he said, “I think that’s something that I’d like to do.”
Healio: What was the procedure itself like?
Rogers: The operation took around 6 hours and went very well. In fact, it was a more straightforward operation than when we were putting this device in calves. The device was designed to go in a human’s chest, so it fit very well.
During the procedure, the bottom two chambers of the heart, which were the diseased chambers, were removed and the artificial heart was attached to a small cuff of the native heart tissue. Then we connected the two cannulae that come off the top of the pump to the pulmonary artery and the aorta, and then tunneled a small electrical cord underneath the skin of the abdomen. That electrical cord delivers energy to the pump and allows a small computer that patients can carry to collect information from the device about its performance.
Healio: What were the 8 days of bridge time like for him?
Rogers: He remained on the ventilator for the first 3 days. We took the breathing tube out on the third day, and he sat up in a chair that day. By the seventh day, he was walking in the ICU. He walked one-tenth of a mile, and on the eighth day he was transplanted. During that time he was, sitting up in a chair, standing and eating. Before we had taken the breathing tube out, he asked if he could have a soda. The first thing that he said when we got the breathing tube out was that he felt great.
He was unable to sense any difference between the mechanical heart and his native heart. He didn’t feel anything different inside of his chest. He recovered the way we would expect following device implantation and the device performed as anticipated. We learned, along with him, about the different kinds of medicines that were most effective to make the pump work optimally.
For example, our hearts pump 5 L or 6 L of blood per minute, at rest. This device was pumping between 8 L and 9 L. When he walked, the device increased the output up to 12 L per minute, without changing any of the settings on the device. The increased output was based upon increased delivery of blood to the pump with exercise.
Healio: When it came time for his transplant, were there any complications during that procedure related to this device being implanted first?
Rogers: No. It was actually a very routine procedure to take out after 8 days. The operation was straightforward, and the transplant was uneventful.
Healio: What is the status of the next total artificial heart recipients? Have they been identified and enrolled?
Rogers: Right now, there are four hospitals in the country that are actively screening patients. We have not identified the next patient, but the early feasibility is a five-patient study for patients awaiting transplantation. It is designed to ensure that the device is safe and that the pump is functioning the way we predicted based on all of our preclinical work.
Once that study is completed, as long as we’re successful, the plan is to design a larger pivotal trial, which will include more centers and include patients who we intend to support for a relatively short amount of time, like people waiting for transplantation, but also patients who we anticipate will need support for longer periods of time and who may not be candidates for transplant. This could be a permanent solution for an individual with biventricular heart failure.
Healio: Are there any smaller implant sizes in development?
Rogers: The device is small. We’re just now beginning to explore the potential that this could satisfy the needs of adolescents. It’s not small enough to put in a child or an infant. At least at the outset, we’re going to focus on adults and potentially down to the adolescent-sized patient.
Healio: Is there anything else you would like to say about this device or the procedure?
Rogers: This was obviously a long development program. So many people in the Houston area supported the development of the device. This is a very unique environment here at the Texas Medical Center.
I would be remiss without calling out the patient and his family for their bravery and commitment to advancing this field. It takes an incredibly thoughtful, courageous person to say, “I’ll be the first to have my heart removed and have a mechanical device put in.”
He has our admiration for his willingness to listen to the story and take that first step. He’s opened the door for a lot of people across the world who may not have access to a viable potentially long-term option for a device.
Editor’s Note: This article was updated on August 13, 2024 to add a comment from SynCardia disputing a characterization of its device.
For more information:
Joseph G. Rogers, MD, can be reached at 6624 Fannin St., Suite 2600, Houston, TX 77030.
References:
- BiVacor. https://bivacor.com/. Accessed Aug. 1, 2024.
- The Texas Heart Institute implants BiVACOR total artificial heart. https://www.businesswire.com/news/home/20240725893070/en/The-Texas-Heart-Institute-Implants-BiVACOR%C2%AE-Total-Artificial-Heart. Published July 25, 2024. Accessed Aug. 1, 2024.
- The Texas Heart Institute provides BiVACOR total artificial heart patient update. https://www.texasheart.org/the-texas-heart-institute-provides-BiVACOR-total-artificial-heart-patient-update/. Published July 26, 2024. Accessed Aug. 1, 2024.
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