Intracardiac Turbines Suitable for Catheter-Based Implantation-An Approach to Power Battery and Leadless Cardiac Pacemakers?

OBJECTIVE: Cardiac pacemakers are powered by batteries, which become exhausted after a few years. This is a problem in particular for leadless pacemakers as they are difficult to explant. Thus, autonomous devices powered by energy harvesters are desired. METHODS: We developed an energy harvester for endocardial implantation. The device contains a microgenerator to convert a flexible turbine runner's rotation into electrical energy. The turbine runner is driven by the intracardiac blood flow; a magnetic coupling allows hermetical sealing. The energy harvester has a volume of 0.34 cm3 and a weight of 1.3 g. Computational simulations were performed to assess the hemodynamic impact of the implant. The device was studied on a mock circulation and an in vivo trial was performed in a domestic pig. RESULTS: In this article, we show that an energy harvester with a 2-bladed 14-mm-diameter turbine runner delivers 10.2 ± 4.8 µW under realistic conditions (heart rate 80/min, stroke volume 75 ml) on the bench. An increased output power (>80 µW) and power density (237.1 µW/cm3) can be achieved by higher stroke volumes, increased heart rates, or larger turbine runners. The device was successfully implanted in vivo. CONCLUSION: The device is the first flow-based energy harvester suitable for catheter-based implantation and provides enough energy to power a leadless pacemaker. SIGNIFICANCE: The high power density, the small volume, and the flexible turbine runner blades facilitate the integration of the energy harvester in a pacemaker. This would allow overcoming the need for batteries in leadless pacemakers.

An Intracardiac Flow Based Electromagnetic Energy Harvesting Mechanism for Cardiac Pacing.

Contemporary cardiac implantable electronic devices such as pacemakers or event recorders are powered by primary batteries. Device replacement due to battery depletion may cause complications and is costly. The goal of energy harvesting devices is to power the implant with energy from intracorporeal power sources such as vibrations and blood flow. By replacing primary batteries with energy harvesters, reinterventions can be avoided and the size of the total device might be reduced. This paper introduces a device with a lever, which is deflected by the blood stream within the right ventricular outflow tract (RVOT), an attractive site for cardiac pacing. The resulting torque is converted to electrical energy by an electromagnetic mechanism. The blood flow harvester weighs 6.4 g and has a volume of 2 cm3, making the harvester small enough for catheter implantation. It was tested in an experimental setup mimicking flow conditions in the RVOT. The blood flow harvester generated a mean power of 14.39 ± 8.38 µW at 60 bpm (1 Hz) and up to 82.64 ± 17.14 µW at 200 bpm (3.33 Hz) during bench experiments at 1 m/s peak flow velocity. Therefore, it presents a viable alternative to power batteryless and leadless cardiac pacemakers.