A ventricular assist device, or VAD, is an electronic heart pump implanted in the chest to support the pumping of one or both ventricles. These devices were originally developed to temporarily support patients with worsening heart failure during the wait for a heart transplant donor. Although they are still utilized for this purpose, VADs are increasingly used in patients whose heart failure has progressed to the end stage but are not eligible for heart transplantation due to age or other medical problems. This technology is rapidly evolving and current generation VADs are compact devices that fit entirely within the chest. They are powered by batteries worn on a harness or hip belt that are connected via a thin power cable (the driveline) that exits the belly. Typically, VADs are available for patients with failure of the left ventricle only. Some devices may be configured to support patients with right ventricular failure or failure of both ventricles.
A ventricular assist device (VAD) helps a weakened ventricle pump blood. Most support the left ventricle and are known as LVADs; they receive blood from the left ventricle and deliver it to the aorta, as shown above. VADs consist of a pump, a control system, and an energy supply. The pump can be located inside or outside the body, while the control system and energy supply are outside the body.
The top panel, above, shows a traditional ventricular assist device. A newer model is shown in the lower panel.
Image Credit: New England Journal of Medicine
Implantation of these devices requires major heart surgery and is not without risk. Patients with implanted VADs require high doses of blood thinners to prevent blood clots, which can cause stroke, from forming in the device. Blood thinners increase risk for bleeding from the nose or in the stool. Because the driveline exits through the abdominal wall, infection is also a concern. Finally, these are mechanical devices, so pump failure requiring replacement can occur.
Despite these complications, patients with implantable VADs who successfully recover from the initial surgical implant can experience substantial improvements in quality and length of life over standard medical treatment. These devices have been transformative for many patients with end-stage heart failure, enabling a high quality of life outside the hospital for many years.