The human heart beats about 100,000 times a day. For the first time in history, machines are learning to do the same.
For centuries, the human heart has been recognized as the engine of life, a vital organ whose failure inevitably leads to death. The quest to create a machine that can replicate its function is one of medicine's most ambitious and dramatic endeavors. What began as a theoretical notion in the 19th century has today evolved into sophisticated devices that can completely replace the human heart, sustaining patients for months or even years. This is the story of the artificial heart—a tale of scientific brilliance, personal tragedy, and relentless innovation that is fundamentally reshaping the boundaries of life and death for patients with end-stage heart failure.
The conceptual foundation for the artificial heart was laid far earlier than most people realize. In 1812, French physician and physiologist César Julien Jean Legallois proposed a remarkably forward-thinking hypothesis. He suggested that the heart's pumping function could be substituted by a syringe continuously supplied with blood, aiming to sustain cerebral and end-organ perfusion1 . While his idea was not practically implemented, it planted a crucial seed.
The first practical steps began in the 20th century. In 1937, Russian scientist Vladimir Demikhov implanted the first biventricular support device in a canine subject, successfully maintaining its life for 5.5 hours1 . Just over a decade later, in 1949, physicians William Sewell and William Glenn constructed a heart pump from an Erector Set, glass cylinders, and rubber tubing, successfully implanting it in a dog with advanced heart failure, which survived for one hour1 .
The modern era of total artificial heart (TAH) development is widely credited to Willem Johan Kolff, a pioneer in artificial organs. On December 12, 1957, he and Dr. Tetsuzo Akutsu from the Cleveland Clinic successfully implanted the first TAH into a dog, which survived for 90 minutes1 . This event marked the birth of a new field of medical science.
The first artificial heart concepts emerged in the early 19th century, but practical implementation only became possible with 20th-century surgical and material science advances.
The leap from animal testing to human application was swift and dramatic. On April 4, 1969, a pivotal moment in medical history occurred at the Texas Heart Institute in Houston. Dr. Denton A. Cooley and Dr. Domingo Liotta replaced a dying man's heart with a TAH1 2 . This Liotta-Cooley heart, consisting of two external pneumatic pumps, supported the patient for approximately 64 hours until a donor heart was available for transplant1 6 . Although the patient ultimately passed away, the procedure proved that a machine could temporarily take over the function of the human heart.
Key Figure: César Legallois
First proposed that a machine could substitute the heart's function1 .
Key Figure: Vladimir Demikhov
First biventricular support device in a dog (5.5-hour survival)1 .
Key Figures: Willem Kolff & Tetsuzo Akutsu
First successful TAH implant in a dog (90-minute survival)1 .
Key Figures: Denton Cooley & Domingo Liotta
First TAH used in a human, bridging to transplant for 64 hours1 .
The most famous chapter in the story of the artificial heart began in 1982 with the work of Dr. Robert Jarvik. Surgeons at the University of Utah implanted the Jarvik-7—the first permanent artificial heart—into Barney Clark, a 61-year-old dentist1 6 . Dr. William DeVries, who performed the surgery, became the first surgeon authorized to implant a permanent artificial heart.
Days Barney Clark lived with the Jarvik-7
Days Bill Schroeder survived with the Jarvik-7 (longest survivor)
The Jarvik-7 was a pneumatic device equipped with two air pumps that simulated cardiac function. Polyurethane discs within each chamber propelled blood from the inflow valve through the device, connected to the patient's natural atria via cuffs1 . An external console, about the size of a refrigerator, supplied electricity and regulated pumping frequency and pressure.
Barney Clark lived for 112 days with the device. His journey was a public spectacle, marked by both hope and immense suffering, and he ultimately died from multiple organ failure1 . Despite the outcome, his experience provided invaluable data. The Jarvik-7 was implanted in several more patients, including Bill Schroeder, who lived for 620 days—the longest surviving patient of the early Jarvik-7 cohort1 .
"While these early implants were surgical successes, they were fraught with complications like strokes, infections, and bleeding, raising ethical questions1 . However, they were conducted on patients who had no other therapeutic options, representing a desperate hope for survival."
The Jarvik-7 would later evolve into the SynCardia temporary TAH, which is still in use today1 6 .
Today's artificial hearts are primarily used as a bridge to transplant, supporting patients with advanced biventricular heart failure until a donor heart becomes available1 6 . They have addressed many early limitations through reduced device size, improved hemocompatibility, and more portable external controllers1 .
Technology: Pneumatic
A groundbreaking study published in Nature Communications in June 2025 illustrates the future of artificial heart technology. An international team of researchers has developed a "Hybrid Heart" that combines soft robotics with advanced biomaterials3 8 . This innovation aims to overcome the poor biocompatibility and non-physiological pumping of previous devices.
The core design philosophy was to mimic the human heart's structure and function more closely than ever before.
The Hybrid Heart contains two artificial chambers separated by a soft pneumatic muscle that acts as a septum. The ventricles and septum are composed of nylon coated with thermoplastic polyurethane3 .
The key to its function is a system of multiple inextensible wires arranged in a closed loop around each ventricle. These wires function like the heart's own muscle fibers3 .
The heartbeat is generated by a clever pneumatic system. Positive air pressure inflates the septum for contraction, while negative pressure deflates it for relaxation3 .
Supramolecular coatings are applied to encourage the body's cells to colonize the device and form a functional inner lining, potentially eliminating the need for lifelong blood thinners3 .
The Hybrid Heart has undergone both laboratory and initial animal testing.
Cardiac output in lab tests (left ventricle)3
Cardiac output in animal testing3
In-Vitro Performance: Under simulated physiological conditions, the device's left ventricle pumped 5.7 liters of blood per minute at a heart rate of 60 beats per minute, which is a normal cardiac output3 .
In-Vivo Validation: In an acute animal test, the device was surgically implanted and was responsible for all blood flow for a 50-minute period. The cardiac output was lower (about 2.3 liters per minute) but demonstrated the device's functionality as a proof-of-concept3 .
Future Potential: The researchers have also developed a fully implantable, closed fluidic system powered by a transcutaneous energy transfer (TET) system. This would allow patients to detach from a power source temporarily, greatly improving quality of life by enabling activities like showering or swimming3 .
The Hybrid Heart experiment demonstrates significant reduction in platelet adhesion and thrombosis, promising potential to reduce blood clot formation and the need for anticoagulation therapy3 .
The journey of the artificial heart is far from over. The next great challenge is to develop a fully implantable, permanent TAH that does not require any external connections, thereby drastically reducing the risk of infection and dramatically improving patients' quality of life2 3 . Devices like the Bivacor and the concepts proven by the Hybrid Heart project are leading this charge.
"There's no mechanical wear. The rotor never touches anything. There's no reason it shouldn't last indefinitely."
The potential impact is staggering. Heart disease remains a leading cause of death worldwide. In the United States alone, end-stage heart failure kills more than 150,000 people annually, while only about 4,500 receive a donor heart transplant2 . A safe, permanent, and shelf-ready artificial heart could close this staggering gap, transforming the treatment of heart failure and becoming one of the most dramatic advances in modern medicine2 .
The story of the artificial heart is a powerful testament to human ingenuity and perseverance. From the theoretical musings of a 19th-century physician to the soft robotic and magnetically levitated pumps of today, this journey has been marked by both breathtaking leaps and sobering setbacks. For the millions of patients waiting for a second chance at life, the steady, silent hum of a machine that has learned to beat is the sound of hope itself.