Effects of vagal nerve excitation on the heart
Dec 03, 2022
Source: Cainiu Health
Dr. Tian Hongbo
Introduction
Excessive vagal activity may lead to impaired cardiac function, resulting in bradycardia and reduced cardiac output, which subsequently causes a drop in arterial pressure and manifests as hypotension. Vagal excitation may also shorten the effective refractory period of the myocardium and slow conduction velocity. Patients may experience symptoms such as palpitations, fatigue, sweating, heart palpitations, dizziness, and others.
Vagal nerve excitation generally affects the heart by reducing cardiac function, slowing conduction velocity, and causing respiratory responses.
1. Reduced cardiac function: Under normal conditions, the vagus nerve exerts an overall inhibitory effect on cardiac activity, decreasing myocardial contractility, slowing heart rate, and reducing conduction velocity. If vagal activity becomes excessive, it may lead to diminished cardiac function, resulting in bradycardia, reduced cardiac output, and consequently decreased arterial pressure, leading to hypotension.
2. Slowed conduction velocity: Following vagal nerve excitation, the effective refractory period of myocardial tissue may shorten, leading to slowed conduction. Patients may experience symptoms such as palpitations, fatigue, sweating, and dizziness. These symptoms are more likely to occur during intense physical exertion or after prolonged sleep deprivation.
3. Respiratory system responses: Vagal nerve excitation can affect the respiratory system, manifesting as slowed respiratory rhythm and increased depth of breathing.
In addition, vagal nerve excitation may also affect the digestive system, increasing gastrointestinal motility and enhancing secretion from the digestive tract.
