Navigating the heart – insights into human coronary artery innervation

The human heart possesses a complex innervation system of sympathetic and parasympathetic nerves mainly involved in regulating coronary blood flow, myocardial contractility, and overall cardiac function. The first systematic approach to understand the autonomic innervation of the human heart dates back to 1926, when Woollard and colleagues described the abundant autonomic innervation of the coronary circulation, emphasising its relevance for cardiac physiology1. In humans, it is known that proximal epicardial coronary arteries (internal diameter 0.8-2.0 mm) exhibit a relatively sparse distribution of nerve fibres, forming a loose network in the adventitia and at the adventitia-media border. Most nerve fibres represent sympathetic nerves, with only few parasympathetic and sensory nerves. In the distal coronary arteries (internal diameter <0.8 mm), nerve fibres are more densely distributed, and the number of sympathetic nerves increases with declining vessel diameter, while parasympathetic nerves remain sparsely distributed even in smaller-sized arteries.

In the current issue of EuroIntervention, Tokcan and colleagues aimed to quantitatively map the periarterial innervation of human coronary arteries to gain further insights into the detailed anatomy of their autonomic innervation2. They examined...