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We provide our users the most up-to-date and accurate information on the treatment and prevention of cardio pathologies in accordance with current American and European clinical guidelines.
The information provided on this website is for educational purposes only and should not be considered medical advice. Always consult a licensed physician for diagnosis and treatment.
Understanding the Causes of Bradycardia
Introduction
Bradycardia is a condition in which the heart rate is slower than normal—typically less than 60 beats per minute in adults. While a low heart rate can be normal in well-trained athletes, it can also indicate underlying medical conditions requiring attention.
Causes of Bradycardia
1. Physiological Causes (Normal Variations)
- Athletic Heart Syndrome: Well-trained athletes often have lower heart rates due to increased vagal tone and improved cardiac efficiency.
- Sleep-Related Bradycardia: During deep sleep, the heart rate naturally slows down due to decreased sympathetic nervous system activity.
2. Pathological Causes
A. Intrinsic Cardiac Causes (Heart-Related Issues)
- Sick Sinus Syndrome (SSS): A condition where the sinoatrial node (the heart’s natural pacemaker) malfunctions.
- Heart Block: A disruption in electrical impulses between the atria and ventricles, categorized into:
- First-degree heart block (mild slowing)
- Second-degree heart block (intermittent failure)
- Third-degree (complete) heart block (dangerous condition requiring a pacemaker)
- Myocardial Infarction (Heart Attack): Damage to cardiac tissue, especially of the inferior wall of the heart, affecting electrical conduction.
- Myocarditis: Inflammation of the heart muscle due to infections or autoimmune conditions.
B. Extrinsic Causes (Non-Heart-Related Factors)
- Medications:
- Beta-blockers
- Calcium channel blockers (e.g., diltiazem, verapamil)
- Digoxin (used in heart failure)
- Antiarrhythmic drugs (e.g., amiodarone)
- Electrolyte Imbalances:
- High potassium levels (hyperkalemia)
- Low thyroid hormone levels (hypothyroidism)
- Neurological Causes:
- Increased vagal tone (e.g., vasovagal syncope)
- Brain injuries affecting the autonomic nervous system
- Infections and Systemic Conditions:
- Lyme disease (can cause heart block)
- Hypothermia (low body temperature slows the heart rate)
When to Seek Medical Attention
Seek medical help if bradycardia is accompanied by: - Fainting (syncope) - Dizziness or lightheadedness - Severe fatigue - Chest pain - Shortness of breath
Conclusion
Bradycardia can be benign or a sign of an underlying condition requiring medical attention. If you experience symptoms, consult a cardiologist to determine the cause and appropriate treatment.
Source recommendations
1. 2023 American Heart Association Guidelines for the Evaluation and Management of Bradycardia
- https://www.ahajournals.org/doi/10.1161/CIR.0000000000000628
- https://pubmed.ncbi.nlm.nih.gov/30412710/
- https://www.ahajournals.org/doi/10.1161/cir.0000000000000499
- https://www.jacc.org/doi/10.1016/j.jacc.2018.10.043
- https://www.heartrhythmjournal.com/article/S1547-5271(23)02026-X/fulltext
2. 2021 European Society of Cardiology Guidelines on Cardiac Pacing and Cardiac Resynchronization Therapy
- https://www.escardio.org/Guidelines/Clinical-Practice-Guidelines/Cardiac-Pacing-and-Cardiac-Resynchronization-Therapy
- https://academic.oup.com/eurheartj/article/42/35/3427/6358547
- https://pubmed.ncbi.nlm.nih.gov/34455430/
- https://link.springer.com/article/10.1007/s12471-024-01927-y
- https://pubmed.ncbi.nlm.nih.gov/34455427/
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If you or your loved ones experience any of these symptoms, you should consult a doctor in time. Remember that self-medication can be dangerous, and timely diagnosis will preserve the quality and life expectancy.
The heart is an organ that does not know how to "keep silent" if something goes wrong. Chest pain, shortness of breath, swelling, dizziness, and rhythm disturbances are the symptoms that require our attention. The best prevention of heart disease is careful attention to your health, regular checkups with a doctor, and a healthy lifestyle. Take care of your heart, and it will serve you for many years!
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