Cardiac Assist Devices: Types, How They Work, and When They’re Used

Cardiac assist devices are mechanical systems that help the heart pump blood when it cannot circulate enough blood to meet the body’s needs. Some devices support the heart temporarily, while others can provide longer-term mechanical circulatory support. They are different from pacemakers and implantable cardioverter-defibrillators (ICDs), which primarily manage problems with the heart’s electrical rhythm rather than its pumping strength.

In this guide, we’ll break down the main types of cardiac assist devices, how they help blood move through the body, and when doctors may recommend them. We’ll also look at how devices such as ventricular assist devices, total artificial hearts, and temporary support systems fit into heart failure treatment, including their potential benefits, risks, and role as a bridge to heart transplant or longer-term therapy.

What Are Cardiac Assist Devices?

When the heart becomes too weak to pump enough blood for the body, cardiac assist devices can provide mechanical support for circulation. These devices, also called mechanical circulatory support devices, can help move blood when the heart’s pumping function is no longer keeping up with the body’s needs. The National Heart, Lung, and Blood Institute describes a ventricular assist device (VAD) as a mechanical pump that helps move blood through the body when the heart cannot pump enough on its own. Depending on the device, support can be provided to the left ventricle, right ventricle, or both.

That support can make a meaningful difference in someone with advanced heart failure. A VAD can take over some of the heart’s pumping workload, moving blood from a heart chamber into a major blood vessel so oxygen-rich blood can continue circulating through the body. The American Heart Association notes that mechanical circulatory support may be considered when optimal medical therapy is no longer enough, including for carefully selected patients with advanced heart failure.

The scale of the problem helps explain why these devices matter. The American Heart Association reported that more than 15,000 patients received mechanical circulatory support between June 2006 and December 2014, with more than 2,000 implants performed annually during that period. For patients supported by then-current continuous-flow devices, reported survival was about 80% at one year and 70% at two years. These figures reflect the technology and patient populations of that period, rather than a prediction for any individual patient today.

It is also important to understand what a cardiac assist device does not do. An assist device is not simply a way to restart a stopped heart or regulate an abnormal heartbeat. A pacemaker helps control the heart’s electrical rhythm, while an ICD can detect dangerous rhythms and deliver an electrical shock to reset the rhythm. A ventricular assist device serves a different purpose: it provides mechanical support for blood flow and heart function.

In practical terms, think of it as giving a damaged heart a helping hand rather than replacing its electrical system. Depending on the patient's condition, that support may be temporary while the heart recovers, a bridge to heart transplantation, or longer-term destination therapy when a donor heart is not an option.

What Are the Different Types of Cardiac Assist Devices?

Cardiac assist devices are not all designed to do the same job. Some provide support for hours or days during a critical illness or procedure, while others can support circulation for months or longer. The main differences come down to which part of the heart they support, how much assistance they provide, and how long the patient needs that support.

The table below gives you a better explanation:

How Does a Cardiac Assist Device Work?

An LVAD is one of the clearest examples of how a cardiac assist device works. The process begins when blood enters the device from the left ventricle through an inflow tube. Since the weakened ventricle cannot pump enough blood on its own, the device takes on part of that workload.

Once blood enters the pump, a mechanical rotor moves it forward. Many modern LVADs are continuous-flow devices, meaning they move blood steadily rather than creating the same pulsing action as a natural heartbeat. The pump then sends the blood through an outflow tube into the aorta, allowing it to continue through the body's circulation.

The LVAD needs an external power source to keep the pump running. A controller monitors the device and connects it to batteries, which patients typically carry with them. A driveline runs from the implanted pump through the skin and connects it to this external equipment. Since the driveline creates an opening through the skin, patients need regular care of the area to help prevent infection.

Once operating, the LVAD helps maintain blood flow throughout the body while reducing some of the work required from the weakened left ventricle. This support can help the body receive enough blood and oxygen to support organ function and, in some cases, allow patients to participate in rehabilitation and everyday activities.

The process is slightly different when the right ventricle needs support. A right ventricular assist device helps move blood from the right side of the heart toward the lungs, where it can pick up oxygen. When both lower chambers are unable to pump effectively, a biventricular assist device (BiVAD) can provide mechanical support to both sides of the heart.

So, while the exact setup depends on the type of device, the basic principle remains the same: the device helps move blood when the patient's heart cannot pump enough on its own. It does not simply restart a stopped heart or regulate its electrical rhythm. Instead, it provides mechanical circulatory support to keep blood moving through the body.

Does a Cardiac Assist Device Replace the Heart?

Usually, a cardiac assist device does not replace the heart. Cardiac assist devices support the heart rather than replace it. Most are designed to take over part of the heart's pumping workload when the patient's own heart cannot circulate enough blood. The heart generally remains in the body and may continue beating while the device provides additional mechanical support.

An LVAD is a good example. It does not remove the patient's heart or replace the entire organ. Instead, the device helps the weakened left ventricle move blood into the body's circulation. This means an LVAD can continue supporting blood flow even though the patient's own heart remains in place.

A total artificial heart is different. It is designed to replace the heart's two lower chambers, or ventricles, and take over their pumping function. Because it replaces a much larger part of the heart's work, it is used in very specific situations, often as a bridge to heart transplant while a patient waits for a suitable donor heart.

So, the difference is fairly simple: an assist device helps a damaged heart pump, while a total artificial heart replaces the ventricles' pumping function. Neither should be confused with a pacemaker or ICD, which primarily address the heart's electrical rhythm.

When Might Someone Need a Cardiac Assist Device?

A cardiac assist device may become an option when advanced or severe heart failure has progressed to the point where the heart cannot pump enough blood despite appropriate medical treatment. It may also be considered when someone experiences an episode of acute circulatory failure, such as cardiogenic shock, where the heart suddenly cannot maintain adequate blood flow to the body's organs. In these situations, mechanical circulatory support can temporarily or permanently take on part of the heart's pumping work.

The reason for using the device matters just as much as the severity of the heart condition. Doctors may recommend a device as a bridge to transplant for someone who is eligible for a heart transplant but is too sick to safely wait for a donor heart without additional support. An LVAD, for example, can maintain circulation while the patient waits for transplantation.

For some patients, transplantation is not possible or is not the preferred option. In these cases, an LVAD may be used as destination therapy, meaning it provides long-term support rather than serving as a temporary step toward a transplant. The goal is to help maintain circulation and improve a patient's ability to live outside the hospital.

There are also situations where doctors do not yet know whether the heart will recover or what the patient's longer-term treatment should be. A device can serve as a bridge to recovery or decision, giving the heart time to recover after a serious cardiac event or giving the healthcare team time to determine the most appropriate next step.

In an emergency, cardiac assist devices can provide support when the heart deteriorates rapidly. Depending on the situation, temporary devices such as an intra-aortic balloon pump or ECMO may be used during severe cardiogenic shock, cardiac arrest, or other forms of acute circulatory failure. These devices can help maintain blood flow while doctors treat the underlying problem.

The treatment goal therefore influences both which device is selected and how long it stays in use. Someone needing temporary support during a critical illness may use a device for days or weeks, while another patient may depend on an LVAD for months or years. The healthcare team considers the patient's heart function, overall condition, transplant eligibility, likelihood of recovery, and treatment goals before deciding which approach makes sense.

What Is It Like to Live With a Cardiac Assist Device?

Living with a cardiac assist device is not simply a matter of having a pump implanted and then getting back to normal. For someone with an LVAD, the device becomes part of how blood moves through the body every day. That changes some routines, but it can also give a person with advanced heart failure more stability, energy, and freedom than they had before treatment.

One of the biggest adjustments is learning to manage the controller and batteries. An LVAD depends on an external power source, so patients need to understand how much battery life remains, carry backup equipment, and know what to do if the power supply is interrupted. Over time, these tasks can become routine, but they still require planning. A trip outside the house, for example, means thinking about battery power and having the necessary backup equipment available.

The driveline requires another layer of attention. Since it passes through the skin, the area where it exits the body can become a potential entry point for bacteria. Patients and caregivers learn how to keep the site clean, secure the driveline, recognize signs of infection, and respond if the area changes. This is not just another postoperative precaution. Infection involving an implanted device can become serious and may require urgent treatment.

Regular follow-up also becomes part of life with mechanical circulatory support. The healthcare team monitors the device, heart function, medications, and the patient's overall condition. Patients may need regular blood tests, particularly when taking anticoagulant medication to reduce the risk of blood clots. The medication itself requires careful management because preventing clots has to be balanced against the increased risk of bleeding.

That balance is one of the realities that can get lost when LVAD treatment is described simply as a way to help the heart pump. The device can improve circulation and quality of life, but it does not eliminate the challenges of severe heart failure. Infection, stroke, bleeding, blood clots, and device malfunction are recognized complications that require ongoing attention. A patient may feel significantly better while still needing to remain vigilant about symptoms and device alarms.

Training is therefore important for both patients and caregivers. Before leaving the hospital, they generally need to understand how the equipment works, how to respond to alarms, how to care for the driveline, and what constitutes an emergency. Having someone else who understands the system can provide an added layer of safety, particularly during the early adjustment period.

Everyday independence can change, but it does not necessarily disappear. Some people on LVAD support are able to return home, participate in physical rehabilitation, resume many daily activities, and spend time with family. Others may need to modify certain activities or rely more heavily on caregivers. The difference often comes down to the patient's health, the type of device, recovery progress, and recommendations from the healthcare team.

What Are the Risks and Complications?

What Happens If an LVAD Stops Working?

Loss of power can be particularly dangerous. Many durable LVADs depend on external batteries, so patients need to keep the system connected to an appropriate power source and carry charged backup batteries. Patients and caregivers are trained to respond to alarms and power interruptions rather than assuming the device will continue operating indefinitely.

There is another detail that can surprise people unfamiliar with LVADs: a patient may not have a palpable pulse even when the device is working properly. Modern durable LVADs commonly use continuous-flow pumps, which move blood continuously rather than producing the same rhythmic pulses as a naturally beating heart. As a result, checking for a conventional pulse is not always a reliable way to determine whether an LVAD patient is receiving adequate circulation.

This is especially important during an emergency. Emergency responders need to know that the patient has an LVAD because standard approaches to assessing circulation, blood pressure, and cardiac status may need to be adapted. Patients should carry their LVAD identification card and emergency information, including details about their device and healthcare team, so responders can quickly understand what they are dealing with.

For an LVAD patient, the pump, controller, batteries, and identification information are not just accessories. Together, they form a system that supports circulation—and knowing how that system works can be critical when something goes wrong.

How Do Doctors Decide Which Cardiac Assist Device Is Appropriate?

There is no single “best” cardiac assist device for every patient. The right choice depends onwhat the heart needs help with, how urgently that help is needed, and what the patient hopes to achieve from treatment. A specialized multidisciplinary healthcare team may include heart failure specialists, surgeons, cardiologists, nurses, pharmacists, rehabilitation specialists, and other professionals who assess the patient's situation together.

The first question is often which ventricle needs support. If the left ventricle cannot pump enough blood into the body's circulation, an LVAD may be appropriate. If the right ventricle is failing, a right ventricular assist device may be considered. When both lower chambers are struggling, doctors may consider biventricular support or, in selected circumstances, a total artificial heart.

Doctors then consider whether the patient needs temporary or long-term support. Someone experiencing sudden circulatory collapse may need a temporary device while doctors treat the underlying problem. A patient with advanced heart failure that has not responded adequately to treatment may instead need durable mechanical circulatory support that can remain in place for a much longer period.

The possibility of a heart transplant also changes the decision. If a patient is eligible for transplantation but is too sick to safely wait for a donor heart, a VAD may be used as a bridge to transplantation. If transplantation is not appropriate, an LVAD may instead be considered as destination therapy, providing long-term support without an expectation of transplant.

The severity of circulatory failure is another major consideration. Doctors look at whether the heart is providing enough blood to the body's organs and how unstable the patient's condition has become. They also examine the function of other organs, including the kidneys, liver, lungs, and brain. A mechanical pump can improve blood flow, but it cannot automatically reverse damage that has already occurred elsewhere in the body.

Surgical risk matters, too. Previous heart surgery, bleeding risk, infection, blood vessel problems, frailty, and other medical conditions can affect whether a particular device can be safely implanted. The team has to consider not only whether the device can improve circulation, but whether the patient can safely undergo the procedure and manage its demands afterward.

Life after implantation is part of the decision as well. Durable VADs require patients and caregivers to understand the controller, batteries, driveline care, medications, alarms, and follow-up appointments. Doctors therefore consider whether the patient has the physical and cognitive ability to manage the system and whether adequate caregiver support is available at home.

Perhaps most importantly, the decision should reflect the patient's goals and quality of life. One person may prioritize staying alive long enough to receive a donor heart. Another may want long-term support that allows them to return home and participate in daily activities. Someone else may prefer a temporary approach if there is a reasonable chance of heart recovery.

That is why the most powerful device is not automatically the best device. Mechanical circulatory support is not about choosing the biggest or most advanced pump. It is about matching the type and duration of support to the patient's heart function, overall health, treatment options, and priorities. The best device is the one that provides appropriate support while fitting the patient's medical needs and life beyond the hospital.

Cardiac Assist Devices vs. Pacemakers and Defibrillators

It is easy to group all implanted heart devices together, but they do very different jobs. A cardiac assist device is primarily concerned with blood circulation. A pacemaker or defibrillator is primarily concerned with the heart's electrical system. The distinction matters because someone can have severe heart failure and need more than one type of device for different problems.

Do You Need To Talk To A Heart Specialist?

A cardiac assist device is a major treatment decision, but needing one is not something you can determine from symptoms alone. If heart failure has become difficult to control, symptoms are worsening despite treatment, or your cardiologist has mentioned an LVAD, VAD, mechanical circulatory support, or heart transplant, it may be time for a more specialized evaluation.

A heart specialist can look beyond the immediate symptoms and assess your heart function, blood flow, other organ function, treatment options, and long-term goals. In some cases, mechanical support may provide a bridge to recovery or transplantation. In others, an LVAD may offer longer-term support and help a patient return home and regain some independence.

Frequently Asked Questions

Cardiac assist devices can sound complicated, especially when you're trying to understand what they mean for everyday life. These answers cover some of the most common questions about LVADs, VADs, transplant, device use, and what patients can expect.