番茄社区app

Few innovations in surgery carry the same mix of promise, controversy, and urgency as the total artificial heart.

For more than 6 decades, surgeons and engineers have attempted to replace the failing human heart with mechanical substitutes鈥攐ften achieving short-term success, but repeatedly running into the same barriers, including hemolysis, infection, stroke, size constraints, and poor cyclic durability.

Today, however, a growing body of experimental and early clinical evidence suggests the field may be approaching a turning point. Rather than attempting to replicate the heart鈥檚 pulsatile mechanics, investigators are embracing continuous-flow designs built around dramatically simplified architectures鈥攎ost notably, total artificial hearts with a single, magnetically levitated rotor and no valves, membranes, or points of mechanical wear.

Early experience with these devices indicates they may be capable of doing what prior generations could not: providing stable biventricular support with sufficient durability and physiologic adaptability to move beyond short-term rescue and into the realm of longer-term鈥攁nd potentially permanent鈥攖herapy for end-stage heart failure.

For William E. Cohn, MD, F番茄社区app, a cardiothoracic surgeon at The Texas Heart Institute and Baylor College of Medicine in Houston, Texas, this moment represents the culmination of decades of work at the intersection of surgery, engineering, and translational science.

His professional lineage traces directly to the origins of artificial heart research itself. Dr. Cohn trained under Michael E. DeBakey, MD, F番茄社区app, and later joined the group led by Denton A. Cooley, MD, F番茄社区app鈥攖wo giants of cardiovascular surgery whose rivalry helped define Houston as the epicenter of heart surgery innovation.

In many ways, Dr. Cohn has inherited that mantle, working closely with longtime mentor O. H. 鈥淏ud鈥� Frazier, MD, F番茄社区app, and now collaborating with biomedical engineer Daniel Timms, PhD, to pursue a radically reimagined artificial heart.

Dr. Cohn framed the clinical imperative plainly. Heart failure is a global epidemic affecting at least 26 million people worldwide¹鈥�6.7 million adults in the US鈥攁nd remains a progressive, ultimately lethal condition for many. Conservative estimates show that more than 450,000 patients die from heart failure each year in the US alone.² Heart transplantation, while lifesaving, cannot meet that demand.

Annual transplant volumes have continued to steadily increase over the past several decades, with roughly 4,500 donor heart transplantations performed in 2024.³ Even among transplant recipients, though, long-term outcomes remain limited. Dr. Cohn explained that approximately half of patients are dead within 10 years, often from the downstream consequences of immune modulation, which fall into two main categories (over- or under-immunosuppression).

Against that backdrop, the appeal of a durable, shelf-ready artificial heart is obvious. 鈥淚f we had a permanent artificial heart that worked,鈥� Dr. Cohn said, 鈥渋t would become one of the most dramatic advances in modern medicine.鈥�

History Rooted in Houston

The modern history of artificial heart development is inseparable from Houston, where much of the earliest work unfolded in the 1960s. Those efforts were driven by bold personalities and an atmosphere that encouraged ambitious experimentation.

Dr. DeBakey, working with Argentinian engineer Domingo Liotta, pursued early artificial heart prototypes through extensive animal experimentation. The work was painstaking and technically limited by the era鈥檚 primitive cardiopulmonary bypass technology; the longest-surviving animal lived only about 24 hours.

Frustrated by the pace of progress, Liotta became convinced that clinical implantation was the only way forward. That conviction set the stage for one of the most dramatic episodes in surgical history. In April 1969, while Dr. DeBakey was in Washington, DC, seeking additional funding, Dr. Cooley implanted an artificial heart into a 46-year-old man with ischemic cardiomyopathy whose heart could not support separation from bypass. The patient and his wife consented to the procedure as a last resort.

The device was a marvel by the standards of its time鈥攁nd crude by today鈥檚. A large bedside console, roughly the size of a small appliance, delivered bursts of compressed air through hoses exiting the patient鈥檚 chest wall. Those air pulses inflated and deflated balloons inside two internal pumps. One propelled blood to the lungs and the other to the systemic circulation.

Hemodynamics were initially excellent. But the device caused severe hemolysis, rapidly destroying red blood cells and precipitating kidney failure. After 64 hours of support, the team performed an emergency heart transplant. In an era before modern immunosuppression, the patient died 32 hours later of sepsis and multisystem organ failure.

The case ignited fierce controversy. Dr. DeBakey returned to Houston furious, severing ties with Dr. Cooley and dismissing staff involved in the operation. The two men did not speak for decades, and the schism reshaped Houston鈥檚 institutional landscape.

The artificial heart used in that first human implant now sits in the Smithsonian Institution, a symbol of both extraordinary ambition and the field鈥檚 earliest limitations.

For Dr. Cohn, that moment was formative. He grew up in Houston during this era and remembers his mother tearing the newspaper article off the front page and placing it next to his cereal bowl. At 8 years old, he brought the article to school and attempted to explain artificial heart technology to his classmates.

鈥淚 emerged as the subject matter expert in my peer group,鈥� he joked. That moment of childhood awe foreshadowed a lifelong dedication to cardiac innovation.

Rethinking the Beating Heart

Despite decades of progress, nearly every total artificial heart developed over the ensuing 70 years shared a common design philosophy: mimic the native heart鈥檚 pulsatility.

According to Dr. Cohn, devices used pusher plates, flexible membranes, and mechanical valves to reproduce systole and diastole. Clinically, many of these systems achieved their intended purpose鈥攌eeping patients alive long enough to receive a transplant with a donor human heart. But mechanically, they all faced the same unsparing reality.

The arithmetic of cardiac motion is brutal. A heart beating 100 times per minute performs roughly 144,000 cycles per day鈥攎ore than 50 million per year. No manmade system with multiple moving parts undergoing cyclic deformation can reliably withstand that workload indefinitely. Mechanical fatigue, membrane failure, valve wear, and bearing degradation are inevitable over time. As a result, total artificial hearts remained, by necessity, temporary devices.

The clearest example is the CardioWest total artificial heart, a descendant of early Jarvik-7 era technology. Since its earliest iterations in the 1980s, nearly 2,000 patients, most on the brink of death, have received versions of this device. The most recent embodiment, the SynCardia temporary Total Artificial Heart, was approved by the US Food and Drug Administration (FDA) in 2004 for clinical use as a bridge to heart transplantation. To date, it remains the only artificial heart approved in the US.

A pivotal 10-year clinical study published in The New England Journal of Medicine found that 79% of patients who received the SynCardia device survived to transplantation, compared to only 46% in a control group.⁴ Yet the limitations are well-known.

Early versions required patients to remain tethered to a massive external console. Although a newer portable driver allows discharge from the hospital, the system still relies on a pair of pneumatic hoses traversing the chest wall鈥攎ajor liabilities for infection. Stroke risk remains high, and when key components fail, the outcome can be fatal. Average support duration remains measured in months, not years.

To Dr. Cohn and many others, the lesson was clear鈥攖he problem was not artificial hearts per se, but the insistence on copying nature too closely. 鈥淲e never built an airplane with flapping wings,鈥� he said. 鈥淢aybe we shouldn鈥檛 be trying to build a beating heart.鈥�

Continuous-Flow Revolution

That insight already had transformed another corner of the field. Beginning in the 1980s and accelerating in the 1990s and early 2000s, ventricular assist devices (VAD) evolved away from pulsatile designs toward continuous-flow pumps built around rapidly spinning impellers. Early concepts were unpolished and often impractical, but they proved a fundamental point: blood could be pumped effectively and safely using rotary flow.

The maturation of VAD technology changed everything. Devices such as the HeartMate II demonstrated that continuous-flow pumps could be small, quiet, energy efficient, and鈥攎ost importantly鈥攍onger lasting. Tens of thousands of patients worldwide received these devices, and long-term survivors began to accumulate. Some patients lived more than a decade or two on a single pump.

Nearly all pulsatile VADs disappeared from clinical use, replaced by newer generations of continuous-flow devices with magnetically or hydrodynamically levitated rotors.

The implications were unavoidable, Dr. Cohn shared. If continuous-flow pumps could support one ventricle for years, why not two?

Extending Continuous Flow to Total Heart Replacement

Early efforts to answer that question involved replacing the excised heart with two independent continuous-flow pumps鈥攐ne for the systemic circulation and one for the pulmonary circulation.

Over roughly 8.5 years, Dr. Cohn, Dr. Frazier, and a team of collaborators implanted such systems in 68 large-animal models. These experiments were technically demanding and often unforgiving. Only 30 animals survived longer than 1 week, and infections were common.

Yet the experiments yielded critical insights. Contrary to long-standing concern, balancing right- and left-sided flows was not the dominant challenge. Continuous-flow pumps exhibit intrinsic automaticity. As inflow pressure rises, flow increases without a change in revolutions per minute, mimicking a Starling-like response. Thus, many animals maintained stable hemodynamics without constant adjustment.

The major Achilles鈥� heel was ingested thrombus on the right side. Small venous clots鈥攕ubclinical pulmonary emboli that mammals generate routinely鈥攃ould lodge in tight-clearance turbines and abruptly halt flow. That observation drove the next design leap: reducing complexity even further.

Single Rotor, Levitated in Space

The pivotal shift came with the arrival of Dr. Timms from Australia. Motivated by his father鈥檚 death from heart failure, Dr. Timms had independently conceived of a titanium-constructed total artificial heart built around a single, double-sided impeller capable of pumping blood to both circulations. The rotor would be magnetically levitated鈥攈eld in space by electromagnets responding to high-frequency sensor feedback鈥攅liminating physical contact, bearings, and mechanical wear. In addition, the right-sided impeller was designed to allow thrombus to pass without affecting right pump function.

鈥淚t鈥檚 like science fiction,鈥� Dr. Cohn said. 鈥淭here鈥檚 no mechanical wear. The rotor never touches anything. There鈥檚 no reason it shouldn鈥檛 last indefinitely.鈥�

When Drs. Cohn and Frazier heard the concept articulated, they recognized its potential, and Dr. Timms, who is now the founder and chief technology officer of BiVACOR, arrived in Houston. They committed fully to the new architecture.

鈥淏ig projects have humble beginnings,鈥� shared Dr. Cohn, BiVACOR chief medical officer. 鈥淎nd when you meet someone brilliant who is working on something that excites you, don鈥檛 let them leave your side.鈥�

What followed was an intense period of digital design and rapid prototyping. Using computer modeling and 3D printing, the team produced dozens of impeller and volute geometries, testing each variant on the bench. Subtle changes in shape produced dramatic differences in flow efficiency, shear stress, and thrombogenic potential. Computational fluid dynamics informed the process, but bench testing with real blood remained the definitive arbiter. Models often failed to predict critical real-world behaviors.

Once geometry was optimized, the team transitioned to metal prototypes using additive manufacturing. Titanium pumps emerged layer by layer from laser sintering machines, then were polished and implanted in animals. Outcomes improved steadily.

After approximately 40 successful implants, regulators required five consecutive animals to survive 30 days. The team met that benchmark, clearing the way for first-in-human experience.

According to BiVACOR, the size of the total artificial heart is suitable for most men and women (body surface area >1.4 m²). Despite its small size, the total artificial heart can provide enough cardiac output for an adult male who is exercising. Using magnetic levitation technology, the same principle used in high-speed trains, the product features a unique pump design with a single moving part. A magnetically suspended dual-sided rotor with left and right vanes positioned within two separate pump chambers forms a double-sided centrifugal impeller that moves blood from the respective pump chambers to the pulmonary and systemic circulations.⁵

The total artificial heart has no valves or flexing ventricle chambers, with magnetic levitation and motor control making pulsatile outflow possible by rapidly modulating the rotor鈥檚 rotational speed once per second. The noncontact suspension of the rotor is designed to eliminate the potential for mechanical wear and provide large blood gaps that minimize blood trauma, offering a durable, reliable, and biocompatible heart replacement. A small external controller, combined with a rechargeable battery system, supports untethered operation from an AC power source to enhance patient mobility and freedom of movement.⁶

Early Clinical Experience鈥攁nd Hard Lessons

Under an FDA early feasibility framework, four US centers with deep artificial heart and transplant expertise were activated. The cohort of five patients all suffered from severe biventricular failure and faced imminent death. Several were supported preoperatively with temporary devices and were deteriorating from right-sided failure.

The first candidate in the study was a 58-year-old man who had suffered from end-stage heart failure. Surgeons at The Texas Heart Institute, including Drs. Cohn and Frazier, successfully implanted the total artificial heart in the patient. The device helped him maintain normal vital signs and organ function for 8 days鈥攗ntil he received a lifesaving heart transplant. The device was tested in four additional patients as well.⁷

Post-implantation, recovery was striking. Patients were mobilized early, walking in hallways within days. One patient walked nearly 2 miles per day. Cardiac output increased autonomously with exertion, without manual pump adjustments. By modulating pump speed, clinicians were able to generate a palpable arterial pulse鈥攕ometimes referred to as 鈥渄igital pulse鈥濃�攁llowing conventional blood pressure cuffs and pulse oximetry to function normally.

鈥淥ne patient told us, 鈥業 don鈥檛 have a heart, literally, and I have not felt this good in I don鈥檛 know how long,鈥欌�� Dr. Cohn said.

Because of trial design, US patients remained in the ICU and were rapidly relisted for transplant, resulting in relatively short support durations. While the study was originally designed to include five patients, an additional 15 patients were added in late 2024. Those patients are expected to receive their devices in the months ahead.

In mid-2025, the titanium total artificial heart received the FDA鈥檚 Breakthrough Device designation鈥攁 formal identification that a device in development should be expedited for patient access.

鈥淭his is more than a regulatory milestone. It鈥檚 a validation of a concept we鈥檝e spent decades proving that a fully implantable, total artificial heart isn鈥檛 just possible, it鈥檚 necessary,鈥� Dr. Timms said in a statement.⁸ 鈥淭he early results from our clinical trial show that we can give them a second chance, without the compromises of older technologies. The Breakthrough Device designation puts us on a faster track to deliver exactly that.鈥�

Parallel experience in Australia allowed discharge home; one patient lived more than 100 days with the device before transplantation.

Not all outcomes were favorable, though. Two later patients in Australia died from intracranial hemorrhage several weeks after implantation. Independent review determined the events were not device-related, implicating blood pressure and anticoagulation management, but the losses were devastating nonetheless. For Dr. Cohn, they underscored that novel devices demand not only engineering excellence, but also rigorous clinical protocols and constant refinement.

Toward Destination Therapy

Despite setbacks, momentum continues. Power requirements for the device are dramatically lower than prior total artificial hearts鈥攐n the order of one watt per liter per minute of flow鈥攎aking transcutaneous energy transfer via inductive coupling increasingly feasible. Ongoing miniaturization already has moved most computing capability into the device itself, with future generations aiming to eliminate external drivelines entirely.

The ultimate ambition is not simply to bridge patients to transplant, but to offer a viable alternative. For the hundreds of thousands of patients with end-stage heart failure who will never receive a donor heart, a small, durable, energy-efficient and blood-friendly artificial heart could redefine the standard of care.

鈥淥ur goal is not to be a bridge to transplant. We think this device could possibly be better than heart transplant and become the gold standard,鈥� said Dr. Cohn.

The journey also has carried symbolic weight for Dr. Cohn. Decades after the falling-out between Dr. DeBakey and Dr. Cooley, both men ultimately stood together at the bedside of an experimental implant, reconciled by the very technology that once divided them鈥攁 moment Dr. Cohn described as a reminder that high-stakes innovation can shape not only technology, but institutions and relationships as well, while also a signal that the long pursuit of a total artificial heart is finally approaching its most consequential chapter.

鈥淲ith breakthrough status in hand,鈥� said Dr. Cohn, 鈥渨e鈥檙e entering the next phase with the wind at our backs and real momentum to bring this to more patients.鈥�

Dr. Cohn delivered the I. S. Ravdin Lecture in the Basic and Surgical Sciences, 鈥淭he Past, Present, and Future of the Total Artificial Heart: A Very Houston-Centric Story,鈥� at the 2025 番茄社区app Clinical Congress in Chicago, Illinois. This presentation was featured in episode 68 of The House of Surgery^庐 podcast.

Listen to The House of Surgery episode.

Jennifer Bagley is Editor-in-Chief of the Bulletin and Senior Manager in the 番茄社区app Division of Integrated Communications in Chicago, IL.

References

1. Savarese G, Lund LH. Global public health burden of heart failure. Card Fail Rev. 2017;3(1):7-11.
2. Centers for Disease Control and Prevention. About Heart Failure. Updated May 15, 2024. Available at: . Accessed January 8, 2026.
3. US Department of Health and Human Services, Health Resources and Services Administration. Organ transplants exceeded 48,000 in 2024; a 3.3 percent increase from the transplants performed in 2023. January 15, 2025. Available at: . Accessed January 8, 2026.
4. Copeland JG, Smith RG, Arabia FA, et al. Cardiac replacement with a total artificial heart as a bridge to transplantation. N Engl J Med. 2004;351(9):859-867.
5. BiVACOR, Inc. Replacing Hearts. Restoring Lives. Available at: . Accessed January 8, 2026.
6. BiVACOR, Inc. BiVACOR Total Artificial Heart. Available at: . Accessed January 8, 2026.
7. The Texas Heart Institute. The Texas Heart Institute provides BiVACOR^庐 total artificial heart patient update. July 25, 2024. Available at: . Accessed January 8, 2026.
8. BiVACOR鈥檚 Total artificial heart receives FDA breakthrough device designation. Business Wire. May 29, 2025. Available at: . Accessed January 8, 2026.