The sudden sinking sensation of the heart is mainly seen in the following cases: 1. Sudden arrhythmias, of which premature ventricular contractions are the most common. Ventricular premature contraction occurs when the heart muscle will appear irregular early contraction, traction around the tissue will appear sudden sinking feeling. Arrhythmias can be caused by a variety of factors, including sudden changes in body position, eating, etc. 2. Sudden nerve stimulation. The heart is innervated by both the sympathetic and parasympathetic nerves, and the sympathetic nerves have the effect of stimulating the heart. After a sudden mental stimulation, the excitement of the sympathetic nerves will lead to strong contraction of the heart, and the above symptoms will appear. 3, other factors, such as sudden exertion, etc., most of them occur in people with heart failure and other underlying conditions.