Pop-Up-Inspired Design of a Septal Anchor for a Ventricular Assist Device

Abstract

Heart failure (HF) is a serious condition in which the heart cannot pump sufficient blood to sustain the metabolic needs of the body. A common indication of failure is a low ejection fraction, or the volumetric proportion of blood ejected when the ventricle contracts. In end-stage HF, support from a ventricular assist device (VAD) can assume some or all of the heart’s pumping work, improving the ejection fraction and restoring normal circulation. VAD therapy options for end-stage right heart failure (RHF) are limited, with only a few FDA-approved devices available for mechanical circulatory support [1]. These devices are based on continuous flow impellers; and despite anticoagulation therapy, use of currently available VADs is associated with thrombogenic risk since the blood must contact artificial non-biologic surfaces. An implantable VAD for RHF based on soft robotic pulsatile assistance has previously been proposed [2]. This device is comprised of a contractile element that is anchored to the ventricular septum and the right ventricle (RV) free wall. The device is programmed to contract in synchrony with the native heart beat and assist in approximating the septum and free wall together in order to augment blood ejection (Fig. 1). Potential advantages of this approach include reduced risk of thrombosis, since there is no blood flow through the lumen of the device, and the possibility for minimally invasive deployment of the device under ultrasound guidance. A key component in this VAD concept is the anchoring mechanism that couples the contractile actuator to the ventricular septum. In this work, we report design, fabrication and testing of a new septal anchor design. We exploit the emerging technology of pop-up MEMS [3] in order to fabricate a collapsible anchoring mechanism. Origami-inspired engineering and pop-up MEMS manufacturing techniques have previously been used for developing disposable and low-cost medical tools and devices [4]. The pop-up anchor can be deployed into the left ventricle (LV) via a standard delivery sheath. We validate the load bearing ability of the anchor and demonstrate deployment in an ex vivo simulation.