The heart beating right within your chest is a vital organ for keeping you alive. Traditionally, it was also believed to operate under the exclusive control of the autonomic nervous system, which sends signals from our brains.

The heart's own neural network, located within the outer layers of its walls, was thought to serve merely as a relay for these brain signals. Yet, according to a new study, this network may play a far more complex role.

Conducted by researchers at Sweden's Karolinska Institute, in close collaboration with researchers at Columbia University, the study revealed that the heart actually has its own intricate nervous system that's essential for regulating its rhythm.

"This 'little brain' has a key role in maintaining and controlling the heartbeat, similar to how the brain regulates rhythmic functions such as locomotion and breathing," detailed Konstantinos Ampatzis, the leader of the study.

Adult zebrafish were analyzed for this research. They're model organisms with cardiac function and heart rates that closely resemble those of humans.

By combining methods like single-cell RNA sequencing, electrophysiological techniques, and anatomical analysis, the team was able to map the organization, composition, and roles of neurons within the heart.

They ultimately identified multiple types of neurons within the organ, and each served distinct roles, including a small group with pacemaker-like functions.

This discovery is groundbreaking, as it questions the conventional understanding of heartbeat regulation and could lead to important clinical advancements.

"We were surprised to see how complex the nervous system within the heart is. Understanding this system better could lead to new insights into heart diseases and help develop new treatments for diseases such as arrhythmias," Ampatzis explained.

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According to the Centers for Disease Control and Prevention (CDC), heart disease is "the leading cause of death for men, women, and people of most racial and ethnic groups" in the United States. Cardiovascular disease results in the death of one person every 33 seconds.

In 2022, heart disease caused a total of 702,880 deaths in the U.S., which is the equivalent of one in every five deaths.

Arrhythmias, on the other hand, refer to abnormal heart rhythms, according to the Cleveland Clinic. They can originate in different parts of the organ and either be too slow, too fast, or simply irregular.

It's estimated that 1.5% to 5% of individuals have arrhythmias, most of which occur due to a problem with the heart's arteries, valves, or muscles.

Symptoms may include chest discomfort, heart palpitations, dizziness or lightheadedness, fainting episodes, shortness of breath, and weakness or fatigue. Still, some people don't exhibit any symptoms, which can make diagnosis difficult.

"We will now continue to investigate how the heart's brain interacts with the actual brain to regulate heart functions under different conditions such as exercise, stress, or disease," Ampatzis concluded.

"We aim to identify new therapeutic targets by examining how disruptions in the heart's neuronal network contribute to different heart disorders."