Understanding Low Pulse Rate (Bradycardia)

Introduction

Bradycardia is a condition where the heart rate is slower than normal. A normal resting heart rate for adults typically ranges from 60 to 100 beats per minute (bpm) . If your heart rate is below 60 bpm, it may be considered bradycardia. A pulse rate of 48 bpm is on the lower end and may or may not be a cause for concern, depending on the individual and their symptoms.

Causes of a Low Pulse Rate

There are several reasons why your heart rate might be lower than usual:

1. Physiological Causes (Normal in Some Individuals)

• Athletes and physically active people often have a naturally lower heart rate due to a well-conditioned heart.
• Sleep and relaxation – Heart rate naturally slows down when you are asleep or completely relaxed.

2. Medical Conditions

• Heart block (conduction disturbances) – Impaired electrical signals in the heart.
• Sick sinus syndrome – A problem with the natural pacemaker of the heart.
• Hypothyroidism (Underactive thyroid) – A slow metabolism can lead to a slower pulse.
• Electrolyte imbalances – Low potassium or calcium can slow down the heart.
• Sleep apnea – Can cause episodes of bradycardia.

3. Medications That Can Lower Heart Rate

• Beta-blockers (e.g., Metoprolol, Atenolol)
• Calcium channel blockers (e.g., Diltiazem, Verapamil)
• Certain antiarrhythmic drugs

When is a Low Pulse Rate a Concern?

Bradycardia is usually only a problem if it leads to symptoms such as: - Dizziness or fainting - Shortness of breath - Chest pain - Fatigue and weakness - Confusion or difficulty concentrating

If you experience these symptoms, you should seek immediate medical attention .

Diagnosis and Treatment

To diagnose bradycardia, a doctor may recommend: - Electrocardiogram (ECG) – Measures the electrical activity of the heart. - Holter monitor – A 24-hour ECG recording to detect irregular rhythms. - Blood tests – To check thyroid function and electrolyte balance. - Exercise stress test – To analyze how the heart behaves under stress.

Treatment Options

• If no symptoms are present and the low heart rate is due to fitness or genetics, no treatment may be needed .
• If bradycardia is caused by medications, adjusting the dosage or changing the medication may be considered.
• For severe cases, a pacemaker may be required to maintain an adequate heart rate.

Conclusion

A pulse rate of 48 bpm may be normal in some people, particularly athletes, but can be concerning if accompanied by symptoms. If you're unsure about the cause of your low pulse, it's best to consult a doctor.

Source recommendations

1. 2023 American Heart Association Guidelines for Bradycardia Management

1. https://cpr.heart.org/en/resuscitation-science/cpr-and-ecc-guidelines/algorithms
2. https://www.ahajournals.org/doi/10.1161/CIR.0000000000000628
3. https://cpr.heart.org/-/media/cpr-files/cpr-guidelines-files/algorithms/algorithmacls_bradycardia_200612.pdf
4. https://www.ahajournals.org/doi/10.1161/CIR.0000000000001194
5. https://pubmed.ncbi.nlm.nih.gov/30412710/

2. 2021 European Society of Cardiology Guidelines on Cardiac Pacing and Resynchronization Therapy

1. https://www.escardio.org/Guidelines/Clinical-Practice-Guidelines/Cardiac-Pacing-and-Cardiac-Resynchronization-Therapy
2. https://pubmed.ncbi.nlm.nih.gov/34455430/
3. https://academic.oup.com/eurheartj/article/42/35/3427/6358547
4. https://pubmed.ncbi.nlm.nih.gov/34455427/
5. https://link.springer.com/article/10.1007/s12471-024-01927-y