Conventional long-term ventricular assist devices continue to be extremely problematic due to infections caused by percutaneous drivelines and thrombotic events associated with the use of blood-contacting surfaces. Here we describe a muscle-powered cardiac assist device that avoids both these problems by using an internal muscle energy converter to drive a non-blood-contacting extra-aortic balloon pump. The technology was developed previously in this lab and operates by converting the contractile energy of the latissimus dorsi muscle into hydraulic power that can be used, in principle, to drive any blood pump amenable to pulsatile actuation. The two main advantages of this implantable power source are that it 1) significantly reduces bacterial infection risk by avoiding a constant skin wound, and 2) improves patient quality-of-life by eliminating all external hardware components. The counterpulsatile balloon pumps, which compress the external surface of the ascending aorta during the diastolic phase of the cardiac cycle, offer another critical advantage in the setting of long-term circulatory support in that they increase cardiac output and improve coronary perfusion without touching the blood. The goal of this work is to combine these two technologies into a single circulatory support system by developing an intermediate volume amplification mechanism. The following seven key design aspects were used to guide the course of the volume amplification mechanism development: a) 4x volume amplification, b) anatomic fit, c) energy transfer efficiency, d) muscle force and speed requirements, e) work storage and delivery, f) material selection, and g) device durability. The muscle-powered counterpulsation system is expected to eliminate driveline complications and avoid surface-mediated thromboembolic events, thereby providing a safe, tether-free means to support the failing heart over extended – or even indefinite – periods of time.
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