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

Area of Science:

• Biomaterials Science
• Cardiovascular Engineering
• Medical Devices

Background:

• Ventricular arrhythmias are often caused by re-entry circuits in the mid-myocardium.
• Current pacing methods struggle to reach these deep myocardial regions due to electrode size limitations.
• Existing treatments like defibrillation and ablation can be painful and invasive.

Purpose of the Study:

• To develop an injectable, conductive hydrogel electrode for pacing mid-myocardial tissue.
• To overcome the limitations of current electrodes in accessing coronary veins.
• To create a less invasive alternative to defibrillation and cardiac ablation.

Main Methods:

• Developed a novel polyether urethane diacrylamide macromer hydrogel matching myocardial stiffness.
• Imparted ionic conductivity to the hydrogel, achieving 2-3X native myocardial levels.
• Utilized a double-barrel syringe with a mixing head for rapid in situ redox-initiated curing.
• Evaluated hydrogel viscosity and cure rate in an ex vivo porcine model.
• Demonstrated in vivo deployment and pacing efficacy in a porcine model.

Main Results:

• The hydrogel electrode demonstrated conductivity comparable to native myocardium, retained post-implantation.
• Stable electrical stimulation was achieved over multiple cycles and significant lengths of cardiac veins.
• The injectable hydrogel successfully filled coronary veins in vivo, reaching deeper and more refined areas than current technology.
• The hydrogel exhibited appropriate viscosity and cure rate for homogeneous deployment.

Conclusions:

• The injectable ionic hydrogel electrode shows promise for pacing previously inaccessible mid-myocardial tissue.
• This technology offers a potential pathway for painless defibrillation and improved treatment of ventricular arrhythmias.
• The developed hydrogel material is stable, conductive, and suitable for minimally invasive cardiac interventions.