The artificial heart is a mechanical device designed either to fully replace or to assist the function of a failing human heart. These sophisticated machines fall under the broader category of mechanical circulatory support (MCS) and represent a modern solution for patients with end-stage heart failure. The development of these devices has been a decades-long effort, driven by the shortage of donor hearts for transplantation. Understanding the artificial heart involves exploring both the complex history of its invention and the various medical roles it fulfills in contemporary cardiac care.
The Early Pioneers and Key Developments
The journey to an implantable artificial heart involved several pioneering figures who advanced the concept from theory to clinical reality. One of the earliest physical concepts was patented in the 1950s by Paul Winchell, an inventor who contributed early designs for a mechanical heart. The first clinical application came in 1969, driven by the work of Domingo Liotta and surgeon Denton Cooley. Cooley implanted Liotta’s device into a dying patient as a temporary measure to sustain life until a donor heart could be found.
This first total artificial heart (TAH) implant kept the patient alive for 64 hours before a human heart transplant was performed. The next major breakthrough centered around Robert Jarvik, who worked with his mentor Willem Kolff at the University of Utah. The resulting Jarvik-7 TAH was the first artificial heart intended for permanent use, implanted into Seattle dentist Barney Clark in 1982. Although Clark survived for 112 days, the early designs highlighted challenges like material compatibility, which led to blood clots, and the cumbersome external power source required for operation.
The Purpose of Cardiac Support Devices
The primary function of mechanical circulatory support devices is to take over the work of a heart that is too weak to pump enough blood to the body’s organs. This necessity arises from end-stage biventricular heart failure, where the heart’s lower chambers can no longer circulate blood effectively. Since the demand for heart transplants far outstrips the supply of donor organs, these devices offer a life-saving alternative.
The medical community defines the use of these devices based on three main indications. The most common indication is “Bridge to Transplant” (BTT), where the device temporarily supports a patient who is eligible for a donor heart but must wait for one to become available. A second role is “Destination Therapy” (DT), which involves the permanent implantation of the device in patients who are not candidates for a heart transplant due to other health issues.
The third purpose, “Bridge to Recovery” (BTR), is less frequent and applies to patients with acute heart failure. The device supports the heart long enough for the native organ to recover its function. In this scenario, the mechanical device can potentially be removed, allowing the patient to live without a replacement heart or long-term support.
Total Artificial Hearts Versus Ventricular Assist Devices
Mechanical circulatory support includes the Total Artificial Heart (TAH) and the Ventricular Assist Device (VAD). A TAH provides complete biventricular support by replacing the native heart’s ventricles entirely. It is attached directly to the patient’s atria, the pulmonary artery, and the aorta, taking over all pumping functions for both sides of the heart. The TAH is generally reserved for patients with severe failure of both ventricles or those whose native anatomy makes VAD placement impossible.
In contrast, a VAD is a partial support system that assists one or both ventricles while leaving the native heart in place. The most common version is the Left Ventricular Assist Device (LVAD), which helps the weakened left ventricle pump oxygenated blood. While earlier devices used a pulsatile flow to mimic a natural heartbeat, modern VADs often employ continuous flow technology, using a spinning rotor to move blood in a steady stream. These continuous-flow VADs are generally smaller, more durable, and are far more prevalent in current practice than the TAH.
Current Applications and Patient Eligibility
Modern mechanical circulatory support is offered to individuals with end-stage heart failure who have New York Heart Association Class III or IV symptoms despite optimal medical management. Patient selection is a rigorous process, involving a comprehensive evaluation of age, overall health, and the absence of other life-limiting organ dysfunction. Candidates for long-term support must have a high probability of survival and improved quality of life with the device.
Living with a modern device involves managing several practical aspects of daily life. Both TAH and VAD systems require an external power source, which connects to the implanted pump via a cable called a driveline that exits the body, usually through the abdomen. Patients must manage the external battery packs and controller, and they must also adhere to a strict regimen of anti-clotting medication to prevent blood clots. While these challenges exist, the technology offers a definitive treatment option, extending and improving the lives of individuals who would otherwise have no hope of survival.