B-po04-044 conductive system capture via in-situ curing hydrogel electrode

The recruitment of large volumes of myocardium has been shown to improve outcomes in pacing therapies. Current lead systems are limited to placement in large vessels due to their size, limiting their recruitment potential. An injectable conductive hydrogel which cures in-situ to fill a venous branch may provide a more robust pacing response by enabling greater myocardial recruitment. To achieve pacing with an injected electrode and compare pacing outcomes to point pacing. Externally cured hydrogel was placed on the epicardium and attached to alligator clips for epicardial unipolar “point” pacing. In another experiment, using a custom catheter system deployed through an 18G sheath, two precursor solutions were injected into the anterior interventricular vein (AIV). The solutions mixed and cured in the AIV branches to form a continuous “line electrode”. A temporary pacing needle was inserted into the gel to supply stimuli. Successful deployment of hydrogel into the AIV was demonstrated by capture and confirmed by ECG. QRS morphologies obtained during IV pacing were narrower than those from epicardial pacing (64 ms vs 96 ms) and better mimicked native sinus morphologies (68 ms QRS) compared to recordings from epicardial point pacing, as shown in Figure 1. Pacing via IV also resulted in an isoelectric gap between the pacing spike and the QRS (Fig. 1B), indicative of bundle branch capture. No such gap was observed during point pacing. Pacing via an injectable electrode may provide a more optimized response compared to point pacing. Further studies will optimize hydrogel properties for long-term application.