Extracardiac Electrophysiology: The Future of Cardiovascular Electrophysiology is Outside the Heart

Modern cardiac electrophysiology (EP) began with intracardiac His-bundle recordings and programmed electrical stimulation. These tools led to a better understanding of arrhythmia mechanisms, which led to more detailed intracardiac mapping, and ultimately to catheter ablation. Modern cardiac implantable electrical device therapy evolved from epicardial to transvenous lead systems, and from single to multisite pacing and defibrillation. Clearly, there continues to be advances in the field of intracardiac EP: better mapping and ablation tools, more accurate intracardiac imaging, and improvements in implantable transvenous lead quality and design, lead delivery systems, and extraction tools. However, an inspection of the recent EP literature would suggest that the future of EP is outside the heart. 

Modern EP that is outside of the heart currently involves not just vascular EP, as it has in the past, but also involves the pericardial space, the subcutaneous space, neural control of the heart and vasculature, and the body surface itself. In the table below are 14 examples of pursuits in a field that could be best described as “extracardiac EP.” The topics are categorized based on their primary location, and whether or not each pursuit would be considered either diagnostic or therapeutic. A recent reference that highlights the potential of the pursuit and emphasizes its current relevance is also provided for each. Some fields, such as body surface mapping, have been around for some time, but have recently been rejuvenated with new applications. Other fields, such as epicardial gene delivery to cardiac ganglia as a method of preventing atrial fibrillation, are novel concepts that are early in development. In most areas, there is evidence of not just technological advances, but also in added value and new indications.

Despite continued progress in intracardiac EP, the future in the field of EP appears to lie outside the heart. The examples provided here, and the pertinent recent references, highlight areas of extracardiac EP that appear to have great potential.

Acknowledgement. Dr. Knight would like to acknowledge Dr. Kenneth Stein, who gave him the idea for this editorial.

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