What Are the Causes of Heart Rate Bradycardia?

Bradycardia is a common disease in middle-aged and elderly people, mainly occurring in those engaged in physical labor or athletes. It is caused by excessive physical exertion leading to slow heartbeat. In middle-aged and elderly people, bradycardia is mostly related to increased blood pressure, excessive potassium levels, and heart diseases. Therefore, for those with a heart rate below 60 beats per minute, it is essential to consider whether the cause of bradycardia is related to organic heart disease.

Physiological sinus bradycardia is a normal phenomenon, commonly seen in individuals who engage in physical labor, athletes, or young people who frequently participate in sports activities. It can also be observed in normal individuals during sleep.

Pathological sinus bradycardia is generally caused by two types of factors: extracardiac and intracardiac. Intracardiac factors include increased intracranial pressure, hyperkalemia, hypothyroidism, hypothermia, and the use of drugs such as digoxin, beta-blockers, reserpine, guanethidine, and methyldopa. Within organic heart diseases, sinus bradycardia can be seen in coronary heart disease, acute myocardial infarction, myocarditis, cardiomyopathy, and sick sinus syndrome.

Clinically, whether individuals with a heart rate below 60 beats per minute will experience symptoms depends on the frequency of bradycardia and the underlying cause. In a resting state, adults with a heart rate between 50 and 60 beats per minute generally do not exhibit obvious symptoms. Especially for well-trained athletes and individuals engaged in physical labor, even if their heart rate is around 40 beats per minute in a resting state, they may not experience significant symptoms. However, for the general population, if the heart rate falls between 40 and 50 beats per minute, symptoms such as chest tightness, fatigue, and dizziness may occur. If the heart rate drops to 35 to 40 beats per minute, hemodynamic changes may occur, affecting the blood supply to the heart and brain organs, leading to symptoms such as chest pain, fainting, and even sudden death.