Have you heard of energy harvesting pacemakers?

When I was a student, I had a wrist watch which would run automatically without the need for a battery or daily winding of the clockwork. I think I still have it somewhere in my almirah as an antique item. There was a mechanism inside it which would keep it running by getting mechanical energy from hand movements. But if you keep in the shelf for over one day or so, it will stop functioning. Similar mechanisms for energy harvesting have been experimented for pacemakers. Currently the limiting factor for pacemakers is the battery life, which necessitates device replacement after a finite period of time. Though nuclear pacemakers were tried sometime back for very long battery life, we don’t hear of them any more. The picture shows the energy harvesting mechanism for an endocardial leadless pacemaker prototype which was tested in a porcine model.

One attempt to develop a heart beat driven lead and battery less pacemaker from Switzerland was published in 2017 [1]. Energy harvesting mechanism of an automatic clockwork was used, after removing the parts meant for indicating time and date. Myocardial contraction provided the energy source in the form of mechanical motion. Dedicated electronic system was developed to process and store the energy. Of the total 1.4W energy of the heart, only about 80 μW was processed and used to power the electronic circuitry of the pacemaker. The prototype pacemaker provided fixed rate pacing at 120/minute with a pulse width of 0.5ms and pacing amplitude of 3V. In a porcine model, the device was directly sutured over the left ventricle. The device had a diameter of 27 mm and height of 8 mm.

Another paper published in 2019 used an elastic skeleton and two piezoelectric composites which could generate high output current of 15 μA in a porcine model for powering a modern fully functional pacemaker [2]. That was also by harvesting the natural energy of the heartbeat, without using any external energy source.

Miniaturized endocardial electromagnetic energy harvester has also been tested for leadless pacemakers [3]. Movements of a mass translated heart’s vibrations into rotation as shown in the cover picture. Permanent magnets on the rotor induced an electric current in a coil placed on the stator, just as in a dynamo generator, though quite miniature.

The prototype was delivered into a 60 kg porcine mode by catheter. Pacing electrodes were placed in low right atrium for atrial pacing and in the right ventricular outflow tract for ventricular pacing.

CC BY 4.0 images of the X-rays in two projections are also illustrated in the paper [3]. Images resemble those from clinically implanted leadless pacemakers. Let us hope that this technology will improve rapidly enable regular clinical implantations of energy harvesting leadless pacemakers in the near future.

References

1. Zurbuchen A, Haeberlin A, Bereuter L, Wagner J, Pfenniger A, Omari S, Schaerer J, Jutzi F, Huber C, Fuhrer J, Vogel R. The Swiss approach for a heartbeat-driven lead- and batteryless pacemaker. Heart Rhythm. 2017 Feb;14(2):294-299. doi: 10.1016/j.hrthm.2016.10.016. Epub 2016 Oct 15. PMID: 27756706.
2. Li N, Yi Z, Ma Y, Xie F, Huang Y, Tian Y, Dong X, Liu Y, Shao X, Li Y, Jin L, Liu J, Xu Z, Yang B, Zhang H. Direct Powering a Real Cardiac Pacemaker by Natural Energy of a Heartbeat. ACS Nano. 2019 Mar 26;13(3):2822-2830. doi: 10.1021/acsnano.8b08567. Epub 2019 Feb 20. PMID: 30784259.
3. Franzina N, Zurbuchen A, Zumbrunnen A, Niederhauser T, Reichlin T, Burger J, Haeberlin A. A miniaturized endocardial electromagnetic energy harvester for leadless cardiac pacemakers. PLoS One. 2020 Sep 28;15(9):e0239667. doi: 10.1371/journal.pone.0239667. PMID: 32986751; PMCID: PMC7521684.