A mechanical heart is a medical device designed to either assist or completely replace the pumping function of a damaged heart. They sustain blood circulation when the natural heart fails. By taking over or augmenting the heart’s workload, they provide a life-sustaining intervention for individuals with severe cardiac conditions.
Why They Are Needed
Mechanical hearts become necessary when a heart is compromised and cannot pump enough blood, a condition known as heart failure. This occurs in end-stage heart disease when traditional treatments fail. Conditions like heart attack, cardiogenic shock, or severe cardiomyopathy can lead to this state.
For many patients, a mechanical heart serves as a temporary measure, providing support while they await a heart transplant. This “bridge to transplant” allows individuals to stabilize and improve health, making them better transplant candidates. They also offer a long-term solution for patients not eligible for transplant.
Types and Components
Mechanical hearts fall into two categories: Ventricular Assist Devices (VADs) and Total Artificial Hearts (TAHs). Each serves a distinct purpose. VADs are mechanical pumps that help the heart’s lower chambers, the ventricles, pump blood.
Left Ventricular Assist Devices (LVADs) are the most common type, assisting the left ventricle to circulate blood to the body. RVADs support the right ventricle’s pumping to the lungs, while BiVADs support both. These devices consist of an internal pump, an inflow cannula drawing blood from the heart, and an outflow cannula directing blood into main arteries. An external controller and battery pack connect via a driveline through the skin, managing operation and providing power.
In contrast, a Total Artificial Heart completely replaces the heart’s damaged lower chambers (ventricles) and valves. It includes artificial ventricles, made from durable materials like polyurethane, and mechanical valves regulating blood flow. The TAH connects to the heart’s upper chambers and major arteries. A portable external driver powers and controls the TAH through drivelines exiting the body.
How They Function
Mechanical hearts move blood through the circulatory system, replicating the heart’s pumping action. For VADs, the pump draws blood from a failing ventricle via an inflow cannula. It then propels blood into the aorta or pulmonary artery, depending on the ventricle supported, via an outflow cannula. This flow circulates blood efficiently.
The external controller of a VAD monitors and adjusts the pump’s speed and function, ensuring adequate blood flow based on activity. The device can increase its pumping rate with activity. TAHs function by having artificial ventricles alternately pump blood to the lungs and body. An external driver pushes air or hydraulic fluid through tubes to power the heart, maintaining rhythm and ensuring circulation.
Life with a Mechanical Heart
Living with a mechanical heart involves adapting to external equipment and ongoing medical management. Patients carry an external controller and battery packs powering the implanted pump. These components are worn in a shoulder bag or belt for mobility.
Daily routines include charging batteries, managing the driveline exit site and performing care to prevent infection. Regular medical follow-ups are part of life, involving checkups, blood tests, and medication adherence. Patients need blood-thinning medications to prevent clots on the device.
For many, receiving a mechanical heart improves quality of life, allowing engagement in activities previously impossible due to severe heart failure. While adjustments are needed, these devices empower individuals to lead active, fulfilling lives. Patients can return to work and participate in physical activities, though strenuous actions may be restricted.