Mechanical support devices are medical technologies designed to assist a heart that is struggling to pump blood. These devices improve cardiac function by supplementing or completely replacing the pumping action of a weakened heart. They provide immediate or long-term support to patients with severe heart conditions, ensuring vital organs receive sufficient blood flow. These devices stabilize patients, alleviate symptoms, and enhance quality of life and survival. Advancements have made these technologies smaller, more efficient, and easier to implant, evolving cardiovascular care.
How Mechanical Support Devices Aid the Heart
Mechanical support devices assist or take over the heart’s pumping function, improving blood output and reducing workload. These devices are broadly categorized into temporary/short-term and durable/long-term support, with distinct goals. Temporary devices stabilize patients during acute cardiac crises, such as cardiogenic shock or severe heart failure, allowing time for recovery or further treatment.
Durable devices offer ongoing support for chronic conditions when the heart cannot recover. They can serve as a bridge to a heart transplant, keeping patients stable while awaiting a donor heart, or as “destination therapy” for individuals not eligible for a transplant. They work by bypassing specific heart chambers or directly assisting the heart’s pumping action, ensuring adequate blood flow to organs. This support restores organ perfusion, reduces symptoms like fatigue and shortness of breath, and improves patient well-being.
Types of Mechanical Support Devices
Mechanical circulatory support includes various devices, categorized by their intended duration of use. Short-term or temporary devices stabilize patients in acute situations.
Intra-Aortic Balloon Pump (IABP)
One common temporary device is the Intra-Aortic Balloon Pump (IABP), which uses counterpulsation. A balloon inflates in the aorta during the heart’s resting phase (diastole) to increase blood flow to the coronary arteries. It then rapidly deflates just before the heart pumps (systole) to reduce left ventricular workload and improve blood output. IABPs are inserted via a catheter, often through the femoral artery, and are available in various sizes to suit patient needs.
Impella Devices
Impella devices are percutaneous temporary circulatory support, functioning as microaxial pumps that draw blood from the left ventricle into the aorta. Models like Impella 2.5, Impella CP, Impella 5.5, and Impella RP offer varying levels of support based on patient needs. Impella 2.5 and CP are typically inserted percutaneously, while Impella 5.5 is often placed surgically for greater support, and Impella RP specifically supports the right ventricle.
Extracorporeal Membrane Oxygenation (ECMO)
ECMO provides comprehensive cardiopulmonary support by moving blood, adding oxygen, and removing carbon dioxide using an artificial lung. Two primary configurations exist: veno-venous (VV-ECMO) and veno-arterial (VA-ECMO). VV-ECMO is used for severe respiratory failure, supporting lung function. VA-ECMO supports both heart and lung function, suitable for cardiogenic shock or cardiac arrest. Cannulation involves placing large tubes (cannulas) into major veins and arteries to facilitate blood flow.
Other Temporary Devices
Other temporary devices include the TandemHeart, which diverts blood from the left atrium to the femoral artery, and CentriMag and Rotaflow pumps. These centrifugal pumps provide short-term support for either the left or right ventricle or both. They are used when high flow rates are needed quickly.
Ventricular Assist Devices (VADs)
For long-term support, Ventricular Assist Devices (VADs) have evolved significantly since their inception in the late 1950s. Early VADs were often large and less efficient. Modern VADs, such as the HeartMate II, Jarvik 2000, HeartMate 3, and HVAD, use continuous flow technology, making them smaller, more durable, and more efficient. These devices are surgically implanted and continuously pump blood from a heart chamber to the aorta, bypassing the weakened heart and providing consistent blood flow.
Total Artificial Heart (TAH)
The Total Artificial Heart (TAH) completely replaces both the left and right ventricles. This device is reserved for patients with end-stage heart failure affecting both sides, who are not candidates for other therapies. TAHs are designed to provide a high volume of blood flow, typically 7-9 liters per minute, ensuring adequate systemic perfusion. While offering complete cardiac replacement, the TAH is a complex device with specific indications and outcomes.
Who Benefits and How They Are Managed
Mechanical support devices are considered for patients with severe cardiac dysfunction, such as cardiogenic shock or advanced heart failure. These devices serve various purposes: as a “bridge to transplant,” sustaining patients while they await a donor heart; as a “bridge to recovery,” offering temporary support hoping the heart regains function; or as “destination therapy,” providing long-term support for individuals not eligible for a heart transplant.
Patient selection involves a thorough evaluation of overall health, potential for recovery, and life expectancy. Medical teams use classification systems like INTERMACS profiles to categorize patients based on their clinical stability and severity of heart failure, guiding treatment decisions.
Once implanted, patient management involves a dedicated care team and continuous monitoring to ensure optimal device function and address issues. Patients are observed for signs of infection at the implant site or driveline, or for bleeding complications from surgery or blood thinners. Teams also manage device-related issues, such as blood clots or mechanical malfunctions. Close collaboration between the patient and medical team ensures successful outcomes, with adjustments made as needed and challenges promptly addressed.
Innovations and the Future of Heart Support
The field of mechanical support devices is advancing through research and technological breakthroughs. Current trends focus on developing smaller, more efficient, and biocompatible devices. This includes fully implantable systems that eliminate external components, reducing infection risk and improving patient mobility and quality of life.
Improvements in battery technology aim for longer battery life and wireless charging, enhancing patient convenience. Researchers explore novel materials and designs to minimize complications like blood clots and infections, improving device safety and long-term outcomes. These innovations strive to make mechanical heart support more accessible, less intrusive, and effective for more patients with heart failure.