The cholecardiac reflex is a phenomenon characterized by a decrease in heart rate, a drop in blood pressure, or even cardiac arrest caused by surgical traction of the gallbladder or exploration of the biliary tract.
The heart is innervated by the T2–8 spinal nerves, while the gallbladder is innervated by the T4–9 spinal nerves, with an overlap occurring at the T4–5 spinal segments. This overlap coincides with a complete reflex arc formed by the vagus nerve. During surgery, stimulation of the gallbladder increases vagal tone and releases more acetylcholine. Acetylcholine travels along the reflex arc, affecting the coronary arteries, which may abnormally contract or even spasm. This results in insufficient myocardial blood supply, leading to ischemia, decreased heart rate, and potentially cardiac arrest.
To illustrate: the gallbladder and the heart both belong to a command center in the cervicothoracic region. Orders from this command center are simultaneously transmitted to the heart and gallbladder, creating a close connection between the two. This explains why patients with acute myocardial infarction may experience upper abdominal pain, and why patients with cholecystitis may also present with shoulder and back pain.