PO-05-087 INCREASED MYOCARDIAL CAPTURE ACROSS AREAS OF SLOWED CONDUCTION BY PACING FROM A HYDROGEL ELECTRODE

Abstract

The efficacy of traditional lead-based systems is limited due to their size. Standard leads are too large to traverse beyond large epicardial vessels, particularly on the left side of the heart where endovascular placement is less practical. Our lab has developed an in-situ curing, biostable, conductive hydrogel, or “liquid wire”, capable of filling venous tributary branches and thus accessing mid-myocardial regions which cannot be captured by standard leads. Electrotherapies delivered via the hydrogel electrode may thus have far greater efficacy due to increased myocardial capture. Assess the extent to which the hydrogel electrode, injected into the AIV, can capture the myocardium compared to traditional point pacing. In acute open chest procedures in three pigs, four different pacing modalities were tested: metal electrode point pacing, a small blob of hydrogel, a pre-cured line of hydrogel on the epicardium, and pacing from the hydrogel electrode in the AIV. ECG tracings were recorded during each pacing modality and compared to baseline sinus rhythm. In another three pigs, acute point pacing and AIV liquid wire pacing were assessed before and after ablation around the AIV to mimic scar tissue using electroanatomical mapping of the epicardium and endocardium. In comparing the four pacing modalities, hydrogel AIV pacing very clearly mimics the baseline sinus tracing, while all others exhibit a typical inverted QRS morphology (Fig 1A). In the mapping comparison, we observe a delay in conduction before and after scar in point pacing (Fig 1B, scar depth in Fig 1C), as well as a dramatic increase in capture when pacing the hydrogel electrode in the AIV after scar formation. There is clear evidence that pacing the hydrogel electrode from the AIV mimics native rhythm and can capture across areas of slowed conduction. There is great potential for this pacing modality to eliminate re-entrant arrhythmias that is not possible in point pacing by virtue of pacing across areas of slow conduction and normalizing myocardial synchronization across those zones (Fig 1D).