Optical mapping and optogenetics in cardiac electrophysiology research and therapy: a state-of-the-art review.

State-of-the-art innovations in optical cardiac electrophysiology are significantly enhancing cardiac research. A potential leap into patient care is now on the horizon. Optical mapping, using fluorescent probes and high-speed cameras, offers detailed insights into cardiac activity and arrhythmias by analysing electrical signals, calcium dynamics, and metabolism. Optogenetics utilizes light-sensitive ion channels and pumps to realize contactless, cell-selective cardiac actuation for modelling arrhythmia, restoring sinus rhythm, and probing complex cell-cell interactions. The merging of optogenetics and optical mapping techniques for 'all-optical' electrophysiology marks a significant step forward. This combination allows for the contactless actuation and sensing of cardiac electrophysiology, offering unprecedented spatial-temporal resolution and control. Recent studies have performed all-optical imaging ex vivo and achieved reliable optogenetic pacing in vivo, narrowing the gap for clinical use. Progress in optical electrophysiology continues at pace. Advances in motion tracking methods are removing the necessity of motion uncoupling, a key limitation of optical mapping. Innovations in optoelectronics, including miniaturized, biocompatible illumination and circuitry, are enabling the creation of implantable cardiac pacemakers and defibrillators with optoelectrical closed-loop systems. Computational modelling and machine learning are emerging as pivotal tools in enhancing optical techniques, offering new avenues for analysing complex data and optimizing therapeutic strategies. However, key challenges remain including opsin delivery, real-time data processing, longevity, and chronic effects of optoelectronic devices. This review provides a comprehensive overview of recent advances in optical mapping and optogenetics and outlines the promising future of optics in reshaping cardiac electrophysiology and therapeutic strategies.

The autonomic nervous system and cardiac arrhythmias: current concepts and emerging therapies.

Research into cardiac autonomic control has received great interest in the past 20 years, and we are now at a critical juncture with regard to the clinical translation of the experimental findings. A rush to develop clinical interventions and implant a range of devices aimed at cardiac neuromodulation therapy has occurred. This interest has been driven by research, superimposed on commercial opportunities and perhaps the more relaxed regulatory framework governing implantable devices and interventions compared with that for pharmacotherapy. However, many of the results of the clinical trials into these therapies have been disappointing or conflicting. This lack of positive results is partly attributable to a scramble to find simple solutions for complex problems that we do not yet fully understand. Are there reasons to be optimistic? In this Review, we highlight areas in the field of cardiac autonomic control that we feel show the most promise for clinical translation and areas in which our current range of blunt tools need to be refined to bring about long-term success in treating arrhythmias.