FEASIBILITY OF LEADLESS CARDIAC PACING USING INJECTABLE MAGNETIC MICROPARTICLES

Introduction: A noninvasive, painless and selective approach for immediate heart pacing would have invaluable implications in several clinical scenarios. We hypothesized that mechano-­electric feedback (MEF) can be utilized to provoke cardiac pacing using injectable magnetic microparticles. Such particles can be trapped in the right ventricle (RV) by an external electromagnet. Thereafter, banging the microparticles against the RV wall, in means of magnetic pulses, can initiate leadless electrical pacing.

Methods: Ex­-vivo, isolated rat and pig hearts were used to test the ability to provoke MEF-induced pacing by iron microparticles (IMPs) inserted directly to the RV cavity. In­-vivo, the localization of IV administered IMPs by an external electromagnet was evaluated by heart cryo­sections. To demonstrate MEF-induced pacing, IMPs were localized in the RV and subjected to magnetic pulses. Overdrive pacing was verified by comparing the arterial pressure waveforms to the magnetic pulses.

Results: Ex-vivo, we found that MEF induced overdrive pacing is consistently applied in isolated hearts. Overall, 5 consecutive hearts were continuously paced. In-­vivo, the electromagnet effectively captured IMPs in the RV; cryosections show large aggregates of IMPs when the electromagnet was used, while sham hearts were vacant (n=2). Moreover, MEF-induced overdrive pacing using IMPs could temporarily revert bradycardia (Fig. 1). Overdrive pacing of at least 4s was obtained in 13 out of 15 tested rats. Proof of concept of our novel methodology in one blood-perfused pig heart confirmed that MEF-induced overdrive pacing is effective in the large mammalian heart as well.

Conclusions: Our results demonstrate for the first time the application of external temporary pacing, in a selective, immediate and painless fashion. This finding may have tremendous clinical implications in the near future.