Sudden rapid heartbeat and panic may be due to physiological conditions such as shock, or pathological causes such as hypoglycemia, tachyarrhythmia, myocardial infarction, pheochromocytoma, and so on. 1. Physiological conditions: When you are frightened, stressed, emotionally nervous, or undergoing strenuous exercise, your heart will suddenly beat faster and panic due to sympathetic excitation, which stimulates the heart. 2. Pathological conditions (1) Hypoglycemia: The sudden decrease of blood sugar leads to the lack of energy supply to the heart muscle and other tissues of the whole body, which reflexively excites the sympathetic nerves and leads to sudden rapid heartbeat and panic. (2) Arrhythmia: such as atrial fibrillation, sinus/supraventricular/ventricular tachycardia, etc. The patient may be of unknown etiology, or it may be secondary to other organic heart disease. (3) Myocardial infarction: Coronary artery plaque dislodgement leads to distal vascular occlusion, the blood supply to cardiomyocytes decreases dramatically in a short period of time, resulting in ischemic necrosis of cardiomyocytes, reduced ventricular ejection, compensatory increase in heart rate and increased blood supply, so there will be a sudden acceleration of heartbeat and heartburn. (4) Pheochromocytoma: adrenal medullary chromophobe tissue intermittently secretes catecholamine hormones, which leads to intermittent increase of cardiac excitability and sudden symptoms such as panic and hypertension. Sudden rapid heartbeat and panic may be related to a variety of factors, and it is recommended to consult a doctor as soon as possible for a clear diagnosis to avoid delaying the condition.