Injectable ionic hydrogel conductors: Advancing material design to transform cardiac pacing

Gabriel J Rodriguez-Rivera; Allison Post; Mathews John; Derek Bashe; Fei Xu; Trace Larue; Abbey Nkansah; Megan Wancura; Malgorzata Chwatko; Christina Waldron; Nikhith Kalkunte; Janet Zoldan; Mathieu Arseneault; Abdou Elgalad; Manuel K Rausch; Mehdi Razavi; Elizabeth Cosgriff-Hernandez

doi:10.1016/j.biomaterials.2024.123071

Injectable ionic hydrogel conductors: Advancing material design to transform cardiac pacing

Biomaterials. 2025 Jan 6:317:123071. doi: 10.1016/j.biomaterials.2024.123071. Online ahead of print.

Authors

Gabriel J Rodriguez-Rivera¹, Allison Post², Mathews John², Derek Bashe³, Fei Xu³, Trace Larue³, Abbey Nkansah³, Megan Wancura⁴, Malgorzata Chwatko³, Christina Waldron³, Nikhith Kalkunte³, Janet Zoldan³, Mathieu Arseneault³, Abdou Elgalad², Manuel K Rausch⁵, Mehdi Razavi⁶, Elizabeth Cosgriff-Hernandez⁷

Affiliations

¹ McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX, 787212, USA.
² Electrophysiology Clinical Research and Innovations, Texas Heart Institute, Houston, TX, 77030, USA.
³ Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA.
⁴ Department of Chemistry, The University of Texas at Austin, Austin, TX, 78712, USA.
⁵ Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA; Department of Aerospace Engineering & Engineering Mechanics, The University of Texas at Austin, Austin, TX, 78712, USA; Walker Department of Mechanical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA.
⁶ Electrophysiology Clinical Research and Innovations, Texas Heart Institute, Houston, TX, 77030, USA; Division of Cardiology, Department of Medicine, Baylor College of Medicine, Houston, TX, 77030, USA.
⁷ Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, 78712, USA. Electronic address: cosgriff.hernandez@utexas.edu.

PMID: 39809077
DOI: 10.1016/j.biomaterials.2024.123071

Abstract

Direct pacing of the mid myocardium where re-entry originates can be used to prevent ventricular arrhythmias and circumvent the need for painful defibrillation or cardiac ablation. However, there are no pacing electrodes small enough to navigate the coronary veins that cross these culprit scar regions. To address this need, we have developed an injectable ionically conductive hydrogel electrode that can fill the epicardial coronary veins and transform them into flexible electrodes. A new hydrogel chemistry based on a polyether urethane diacrylamide macromer was developed that matches myocardial stiffness and is resistant to hydrolysis. Conductivity was imparted using ionic precursor solutions with values in the range of 2-3X of native myocardium that was retained after implantation. Ionic hydrogel electrodes provided stable electrical stimuli over many cycles and across a substantial length of the cardiac vein. Rapid in situ cure was achieved with redox initiation after injection from a double-barrel syringe with a mixing head. An ex vivo porcine model was used to identify the requisite viscosity and cure rate for hydrogel retention and homogeneity. Finally, successful in vivo deployment and pacing in a porcine model demonstrated that the ionic hydrogel electrode filled the anterior interventricular vein to depths far more distal and refined than current technologies. Collectively, these studies demonstrate the potential of this injectable ionic hydrogel electrode to pace previously inaccessible mid-myocardial tissue and pave the pathway for painless defibrillation.

Keywords: Arrhythmias; Biomaterials; Conductive; Hydrogels; Injectable; Pacing.