Above: a Thoratec HeartMate 2. Image courtesy of Thoratec Corp (now Abbott)

A Left Ventricular Assist Device, or LVAD, is a compact mechanical blood pump. It's designed to be implanted inside the human body, as is recommended for patients that have insufficient cardiac outputs (weak hearts). 

As the name indicates, it helps the left ventricle in pumping blood. In normal heart function, the left atrium supplies oxygenated blood to the left atrium via the mitral valve during diastole. Blood is then pumped by the left ventricle to the rest of the body during the systole. If the heart is weakened, not enough blood is pumped, in which case an assist device like an LVAD is needed. Normally, blood is piped from the left ventricle into the LVAD, which then pumps it into the aorta.

An LVAD can serve as a bridge to transplant: as in, if a patient is waiting for a matching donor heart, it can help keep the patient alive until such a heart is available. For patients not eligible for heart transplants, it may serve as a destination therapy. In rare cases, it may be used as a bridge to recovery. This may happen with a patient who has suffered from a heart injury and the heart needs a temporary respite from pumping at full capacity. The LVAD helps keep the patient alive while the heart regains its natural strength. 

Early generations of LVADs were designed for pulsatile flow, in accordance with natural bodily pulsatility. Such systems were however bulky and had short life cycles. Current generations of LVADs are continuous flow, which is not in accordance with natural bodily function, but they do have longer lifespans and are more compact. BRAHMA Labs is engaged in producing a compact, low-power device that is plugged downstream of the continuous flow LVAD, and can produce natural pulsatility in the blood flow. 

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