 | It has been suggested that this article be merged with Ganglionated plexi . ( Discuss ) Proposed since August 2025. |
The Intrinsic cardiac nervous system (ICNS), also known as the heart's "little brain," is a complex network of neurons and ganglia embedded within the heart tissue that regulates cardiac function independently of the central nervous system. It modulates heart rate, conduction, and cardiac contractility in response to local and external stimuli. [1] [2]
The ICNS consists of clusters of neurons, or ganglia, primarily located in the atrial and ventricular walls, with higher concentrations in the sinoatrial (SA) and atrioventricular (AV) nodes. [1] [3] These ganglia contain: [1] [4]
The distribution of ganglia varies across species, with larger mammals (e.g., humans, dogs) having more extensive networks than smaller mammals (e.g., mice, rats). [1]
The ICNS originates from neural crest cells (NCCs) during embryonic development: [1]
The ICNS integrates sensory information from the heart and coordinates local reflexes. [1] Key functions include: [1] [5]
The ICNS interacts with the autonomic nervous system (ANS), receiving input from sympathetic and parasympathetic pathways, but can operate autonomously during disruptions, such as in heart transplants. [1]
ICNS neurons release neurotransmitters like acetylcholine, norepinephrine, and neuropeptides (e.g., substance P, neuropeptide Y, vasoactive intestinal peptide (VIP)). [1] [8] These mediate local signaling and modulate ion channels in cardiac cells, affecting cardiac action potentials and contractility. The system exhibits plasticity, adapting to chronic conditions like heart failure or hypertension. [1] [9]
Dysfunction in the ICNS is implicated in arrhythmias (atrial fibrillation), sick sinus syndrome, heart failure, and sudden cardiac death. Its role in denervated hearts (e.g., post-transplant) highlights its capacity for independent function. Research explores ICNS-targeted therapies, such as neuromodulation, to treat cardiac disorders. [1]
The ICNS was first described in the 19th century through histological studies of cardiac tissue. Advances in electrophysiology and imaging in the 20th century elucidated its functional role. [1] [10]