Injectable hydrogel electrodes as conduction highways to restore native pacing

There is an urgent clinical need for a preventative treatment regimen that addresses the underlying pathophysiology of ventricular arrhythmias, the leading cause of sudden cardiac death. The current report describes a new approach in cardiac rhythm management that leverages the native coronary anatomy for creation of flexible electrodes to directly and uniformly stimulate mid-myocardial tissues. Successful in vivo deployment of an injectable hydrogel electrode was achieved in a pig model via the rapid, in situ gelation of the two component hydrogel precursors to transform the vein into a flexible electrode with access far more refined than any current technologies allow. In addition to successful capture and pacing of the heart, analysis of surface ECG tracings and three-dimensional electroanatomic mapping revealed a QRS morphology comparable to native sinus rhythm, strongly suggesting the hydrogel electrode captures the deep septal bundle branches and Purkinje fibers. In an ablation model, electroanatomic mapping data demonstrated that the activation wavefront from the hydrogel reaches the mid-myocardium and endocardium much earlier than current single-point pacing modalities. Such uniform, controlled activation of broad swaths of tissue with wavefront propagation from the hydrogel electrode enables a unique opportunity to minimize the delayed myocardial conduction of heterogeneous tissue that underpins re-entry. Chronic studies using a pig model confirmed safety with absence of myocardial necrosis or retention of myocardial function. Collectively, these studies demonstrate the feasibility of a new pacing modality that most closely resembles native conduction with the potential to eliminate lethal re-entrant arrhythmias and provide painless defibrillation.