Ventricular arrhythmia, a serious heart condition occurring in the lower chambers or ventricles, is a primary cause of sudden cardiac death. This condition involves a self-sustained heart rhythm abnormality known as re-entrant arrhythmia, which can be life-threatening. Currently, arrhythmias are treated with medications and procedures aimed at regulating irregular heartbeats. However, the available anti-arrhythmic drugs are not always effective and can sometimes exacerbate re-entrant arrhythmia by slowing conduction velocity. Additionally, these drugs can be toxic and may harm tissues near the heart's diseased areas. Interventional ablation therapies, though widely used, see arrhythmia recurrence in a significant number of patients and don't address the re-entry mechanism. Implanted cardiac defibrillators, designed to offset these limitations, can be painful when delivering electric shocks to normalize heart rhythm, impacting patient quality of life. Untreated, arrhythmia can harm the heart and other organs, potentially leading to stroke or cardiac arrest.

The need for an effective therapeutic regimen for ventricular arrhythmia encouraged researchers at the Texas Heart Institute (THI, Houston, TX, USA) to develop an innovative treatment approach specifically targeting the pathophysiology of re-entrant arrhythmia. In a breakthrough study, the researchers have demonstrated the design and feasibility of a new hydrogel-based pacing modality, setting the foundation for a ground-breaking treatment regimen for treating ventricular arrhythmia. The hydrogels, known for their biostability, biocompatibility, and tunable properties, are being investigated as potential electrodes that can be efficiently delivered into coronary veins while avoiding ischemia. Re-entrant arrhythmia often originates from delayed conduction in scarred heart tissues following coronary artery occlusion, typically during a heart attack. This can be remedied by pacing these areas.

The THI researchers have designed hydrogels that can reach scarred tissues, thus allowing direct pacing of heart regions that are otherwise hard to access. Once injected into targeted vessels, these conductive hydrogels adapt to the patient's vessel shape. Integrating these gels with a conventional pacemaker enables pacing that imitates the heart's natural electrical rhythm, effectively neutralizing the arrhythmia source and offering pain-free defibrillation. This innovative hydrogel technology was successfully tested through minimally invasive catheter delivery in a pig model. The study is the first to demonstrate the ability to directly electrically stimulate both native and scarred mid-myocardium using injectable hydrogel electrodes as a pacing modality. By combining this with standard pacemaker technology and minimally invasive delivery methods, the study demonstrates the viability of a new pacing approach that mimics the heart's natural electrical rhythm. This could potentially eliminate lethal re-entrant arrhythmias and provide painless defibrillation while integrating smoothly into clinical practice. This significant scientific breakthrough, particularly in terms of pain management for patients with heart, lung, and blood diseases, could transform the management of cardiac rhythms. 

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