What causes sinus bradycardia?

Sinus bradycardia refers to a slow heart rate originating from the sinus node. Sinus bradycardia occurs when the heart's pacemaker is located in the sinoatrial (SA) node, but the heart rate is abnormally slow. It may be caused by factors such as medication effects, electrolyte imbalances, excessive vagal tone, hypothyroidism, or acute myocardial infarction. Different underlying causes require specific interventions. It is recommended to seek timely medical evaluation to avoid delayed treatment. Detailed analysis is as follows:

1. Medication effects: Certain medications, such as beta-blockers and some antiarrhythmic drugs, can slow the heart rate. Long-term use may lead to sinus bradycardia, accompanied by symptoms such as fatigue, dizziness, and palpitations. It is advisable to adjust the dosage or switch medications under medical supervision.

2. Electrolyte imbalances: Imbalances such as low potassium or low magnesium levels can affect the heart's electrical activity, leading to a slowed heart rate and resulting in sinus bradycardia. Symptoms may include weakness, muscle fatigue, and arrhythmias. Daily supplementation of deficient electrolytes and dietary adjustments—such as consuming more bananas, sweet potatoes, and nuts—can help correct these imbalances.

3. Excessive vagal tone: Overactivity of the vagus nerve can suppress the function of the SA node, slowing the heart rate and causing sinus bradycardia. This may be accompanied by dizziness or fainting. Symptoms can be improved through lifestyle modifications, such as avoiding forceful coughing, neck massage, and ensuring adequate sleep.

4. Hypothyroidism: Low levels of thyroid hormones result in a reduced metabolic state, which slows the heart rate and leads to sinus bradycardia. Symptoms may include fatigue, dry skin, and cold intolerance. Treatment under medical guidance may include medications such as levothyroxine sodium tablets, Yikang capsules, or hydrocortisone tablets.

5. Acute myocardial infarction: Acute myocardial infarction occurs when atherosclerotic plaques in the coronary arteries rupture, causing vessel blockage. This can impair cardiac conduction and lead to sinus bradycardia, often accompanied by chest pain and shortness of breath. In emergencies, medications such as amlodipine atorvastatin calcium tablets, dicoumarol tablets, or metoprolol tartrate tablets may be prescribed to manage symptoms.

The treatment of sinus bradycardia depends on the specific cause and the severity of symptoms. If any cardiac symptoms occur, prompt medical attention is advised to obtain professional diagnosis and treatment. A physician will develop an appropriate treatment plan based on a comprehensive assessment.