Po-05-086 hydrogel electrode sub-acute safety in a porcine model

Our lab has developed a biostable, in-situ curing hydrogel with conductive properties enabling its use in electrotherapies. This hydrogel is formed by the reaction between two precursor solutions, enabling intravascular delivery via a catheter system. By virtue of its fluid nature prior to curing, this "liquid wire” can fill mid-myocardial venous tributaries, presenting significant advantages over standard pacing systems. The length of the liquid wire enables synchronization of pacing across scar regions. For this technology to be further developed, it must first demonstrate long-term safety as a chronic implant. Determine the initial safety of the hydrogel electrode in the anterior intraventricular vein (AIV) over four weeks and the middle cardiac vein (MCV) over two weeks. The hydrogel electrode was delivered into the AIV using a dual barrel syringe via an open chest procedure in 3 pigs. The pigs were recovered and observed for four weeks with weekly blood draws to assess troponins. A similar procedure was performed for the MCV in one pig and the animal was recovered and observed for two weeks. ECG tracings were recorded before injection and immediately before termination. Echocardiography was performed to assess EF. The lungs, liver, and brain were collected for gross examination for hydrogel particulates. The hearts were collected, fixed, and stained (Mason’s trichrome, hematoxylin, and eosin) to assess foreign body response and remodeling. Little change was observed in ECG tracings for all animals (Fig 1A). Troponins were high immediately after the procedure, likely due to the invasive surgery, but these values trended down towards normal levels (45-54 ng/L, Fig 1B). EF values remained in normal ranges (65-69%). Histological analysis (Fig 1C) shows a giant foreign body cell reaction immediately surrounding the vessel, along with some replacement fibrosis, likely due to the vessel dilation. The surrounding myocardium remains well preserved. The subacute implantation of the hydrogel electrode into cardiac veins has no deleterious effect on overall cardiac function. Future studies will explore the hydrogel electrode function and safety in diseased porcine hearts as well as the testing of the total endovascular delivery system that could potentially limit the dilation of the vessel.