Melhem, N J

Abstract Introduction Energy harvesters that convert biomechanical energy into electrical power could be used for implantable devices, providing a near-infinite energy solution. While various energy harvesters with piezoelectric or triboelectric elements have been designed and applied to the cardiac environment, none have been successfully integrated into leadless pacemakers due to their size constraints or insufficient energy generation. Purpose This study aimed to test the performance of a novel self-sustaining leadless pacemaker, which operates on a proprietary inertial piezoelectric energy harvester (PEH) capable of generating the energy required for VVI therapy from the beating of the heart. Method A novel autonomous Leadless Pacing System (ALPS), including a leadless implant, a customized delivery tool catheter, and a home monitor, was developed. The leadless implant was designed to operate on the energy generated by a specially designed PEH that could fit inside the implant. The harvester’s energy was used to charge a small rechargeable backup battery, which provided the energy for a VVI single-chamber therapy. The leadless device and its dedicated delivery tool were then tested in vivo in an ovine model, adhering to the principles of laboratory animal care and with local ethical approval. Results The heart contractility creates harmonic movement in the heart tissue, which is transmitted into the PEH, resulting in the PEH acceleration. The leadless PEH components transform these mechanical forces into electric energy. In pre-clinical testing on an AV block ovine model (n=7), the device was able to pace the animals for 3 months, at 100% pacing, with an average pacing capture threshold of 0.9 (+/-0.5)V, with a pulse width of 0.366 msec, an average impedance of 570 (+/- 115) Ohm, and daily communication with the home monitor device. Conclusion This work demonstrates that a novel leadless pacemaker that utilizes a piezoelectric element to harvest the heart's mechanical energy to generate electrical energy successfully sustains VVI therapy. This approach is able to produce enough energy to maintain device longevity and support additional functionality, such as daily wireless communication with a home monitor, overcoming major limitations of leadless cardiac devices.

Abstract Intro Energy harvesters that convert biomechanical energy into electrical power could be used for implantable devices, providing a near infinite energy solution. While various energy harvesters with piezoelectric or triboelectric elements have been designed and applied to the cardiac environment, none have been successfully integrated into leadless pacemakers due to their size constraints or insufficient energy generation. Purpose This study aimed to develop a proprietary inertial piezoelectric energy harvester (PEH) capable of generating the energy required for a self-sustaining leadless pacemaker from the beating of the heart. Method Human heart dynamics were tested using ultra-fast MRI scans of 20 patients, which were analyzed for displacement of the right ventricular (RV) apex, mid- to low septum, and the right atrial (RA) walls. The data was used to design the PEH, which was evaluated in thirteen (13) male swine. In addition, epicardial MEMS-based sensors recorded the acceleration, angular positions, and gravity in 3 directions. The sensors were placed at the apex of the RV, LV Apex, LV free wall, and the RA using adhesive means. The data collected from the animals was used to calculate the power produced by the PEH in the different regions of interests and to create a bench model to optimize the PEH design further. The PEH was then tested in-vivo in an ovine model. Results The heart contractility creates harmonic acceleration in the heart tissue, transmitting this vibration into the PEH, resulting in the harvester acceleration of 0.75 g (±0.25g). When the PEH is subject to vibrations, the PEH oscillates using kinetic forces exerted on the piezoelectric beam through a proof mass, transforming these mechanical forces into electric energy. The electrical energy produced using this PEH is 6µW (± 2µW), which is sufficient to power a leadless pacemaker, providing pacing therapy of 100% pacing, at 60 BPM, with heart impedance of 600 (±200), and a pacing voltage reaching 2V, with sufficient excess energy to maintain charge of a secondary battery used for communication and advanced pacemaker functions. This was then tested in a pre-clinical setup, using an ovine model (results to be presented in the future). Conclusion This work demonstrates that a proprietary inertial PEH can use the contraction energy of the heart to generate electrical energy. The design of the PEH was based on the analysis of human heart kinetics using MRI scans and in-vivo recordings from pigs’ hearts. This design of an effective energy harvester can produce enough energy to power a leadless pacemaker. The design can fit in a small capsule that can be used in a leadless pacemaker that will be implanted in the RV providing sensing and pacing as well as daily communication enabling advanced pacemaker functions. The PEH is currently being tested in an ovine model, demonstrating its safety and performance.