- Bradycardia is a medical condition characterized by an abnormally slow heart rate, typically defined as fewer than 60 beats per minute (bpm) in adults. While a normal resting heart rate ranges between 60 and 100 bpm, bradycardia does not always indicate a health problem.
- In certain individuals, such as well-trained athletes or people who sleep deeply, a low heart rate may be entirely normal and reflect efficient cardiovascular function. However, in others, especially when accompanied by symptoms, bradycardia may signal an underlying issue with the heart’s electrical conduction system or another medical condition.
- The heart’s rhythm is normally controlled by the sinoatrial (SA) node, which serves as the natural pacemaker. Bradycardia occurs when the SA node generates electrical impulses too slowly, or when those signals are delayed or blocked as they travel through the atrioventricular (AV) node or other parts of the conduction pathway. This can lead to sinus bradycardia (a consistently slow rhythm from the SA node), sick sinus syndrome (where the pacemaker function is erratic), or heart block (where electrical signals are partially or completely blocked between the atria and ventricles). These conduction problems may reduce the heart’s ability to pump blood effectively.
- The symptoms of bradycardia depend on how much the slow heart rate affects circulation. Some individuals may have no symptoms at all, while others may experience fatigue, dizziness, weakness, shortness of breath, chest discomfort, confusion, or fainting (syncope). Severe or untreated bradycardia can reduce oxygen supply to vital organs and, in extreme cases, may result in heart failure, cardiac arrest, or sudden death.
- Bradycardia can be caused by a variety of factors. Physiological bradycardia occurs naturally in athletes or during rest and sleep. Pathological causes include aging-related changes in the heart, ischemic heart disease, myocarditis, hypothyroidism, electrolyte imbalances (such as high potassium levels), certain infections, and medications such as beta-blockers, calcium channel blockers, and digoxin. In some cases, bradycardia is temporary, while in others it indicates chronic heart conduction abnormalities requiring long-term management.
- Diagnosis typically involves a physical examination, electrocardiogram (ECG), Holter monitoring, blood tests, and sometimes exercise stress tests or echocardiography to assess structural or functional heart problems. Treatment depends on the severity and underlying cause. If bradycardia is asymptomatic and not harmful, no treatment may be necessary. However, if symptoms are present or if the slow rate impairs cardiac output, management may include adjusting or discontinuing medications, treating contributing medical conditions, or implanting a pacemaker to regulate heart rhythm.
