The heart, an essential organ for bloodBlood is composed of red blood cells, white blood cells, platelets, and plasma. Red blood cells are responsible for transporting oxygen and carbon dioxide. White blood cells make up our immune defense system. Platelets contribute to blood circulation, is equipped with a sophisticated electrical system that coordinates its contractions to ensure efficient bloodBlood is composed of red blood cells, white blood cells, platelets, and plasma. Red blood cells are responsible for transporting oxygen and carbon dioxide. White blood cells make up our immune defense system. Platelets contribute to blood distribution throughout the body.
Its command center, the sinoatrial node, located in the right atrium, serves as the natural pacemaker, initiating each heartbeat and determining its frequency.
Previous Chapter: The Heart’s Electrical System
Heart Rate Varies Throughout the Day
It is normal for heart rate to fluctuate during the day.
The heart beats more slowly when at rest and accelerates during physical activity or in response to stressful situations, for example.
Influenced by Internal and External Factors
Circulating hormones, emotional stress, brain responses, and various substances or medications can stimulate this system. These factors explain why the heart can speed up or slow down depending on the body’s needs.
Bradycardia
When the heart rate drops below 60 beats per minute, it is referred to as bradycardia. This slower rate can be a natural response or, in some cases, a sign of a rhythm disorder.
Sinus Bradycardia
At Rest and During Sleep: During rest or sleep, the heart naturally slows down.
In athletes or individuals who regularly engage in cardiovascular exercises such as running or cycling, a heart rate below 60 beats per minute is common and typically harmless.
Heart’s Adaptability
This slow heart rate at rest is not problematic and adjusts as needed.
When the individual becomes active, even during light activities like walking, the heart speeds up to meet the increased oxygen demands.
Impact of Medications
Certain medications, particularly beta-blockers, can slow the heart rate. These medications, often recognizable by their generic names ending in “lol” (e.g., atenolol, metoprolol, bisoprolol), are designed to deliberately reduce the heart’s workload by controlling its rhythm.
This controlled reduction in heart rate is intentional and beneficial for treating conditions such as coronary arteryThe two coronary arteries, the right and the left, form the blood network that supplies the heart with oxygen and nutrients. They are located directly on the surface of the heart and branch into smaller vessels that disease, heart failure, or specific types of arrhythmias.
Accuracy of Modern Technology
Heart rate readings from smartwatches, bloodBlood is composed of red blood cells, white blood cells, platelets, and plasma. Red blood cells are responsible for transporting oxygen and carbon dioxide. White blood cells make up our immune defense system. Platelets contribute to blood pressure monitors, or pulseThe pulse is the sensation of beating that one feels by applying slight pressure on an artery, usually at the wrist or neck. It corresponds to the blood flow pulsated by the heart through the arteries with oximeters can sometimes falsely indicate a lower rate.
These devices measure heart rate based on detected pulses, but premature heartbeats (extrasystoles) may not generate strong enough pulses to be recorded. Some individuals may not even notice these irregularities.
Learn More: Extrasystoles, A Medical Perspective
Symptoms Are Rare or Mild
Bradycardias often cause little to no symptoms.
In severe cases, patients may experience subjective symptoms such as weakness or dizziness. If these symptoms occur, a doctor may recommend the use of a long-term ambulatory recorder like a Holter monitor.
The Holter Monitor
This device records heart rate throughout the day, helping to determine the severity of bradycardia and its connection to the patient’s perceived symptoms.
Learn More: The Holter Monitor
Treatment
For secondary sinus bradycardia, treatment involves addressing the root cause of the symptomatic slow heart rate.
A thorough review of the patient’s medications is often the first step. The doctor may adjust dosages, replace, or discontinue specific medications contributing to the bradycardia.
Always Carry a Medication List
It is essential to have an up-to-date list of medications when visiting healthcare professionals. Do not assume they already have this information.
Request a “health booklet” from your pharmacist to carry with you at all times.
Pacemakers Are Rarely Needed
In the rare instances where the heart’s natural pacemaker fails to maintain an adequate rate, a pacemaker—commonly called a cardiac stimulator—may be required.
Conclusion
Sinus bradycardia is frequently a normal adaptation of the heart’s electrical system and often does not require medical intervention.
In cases where bradycardia is suspected—such as when detected by wearable technology—a Holter monitor can help accurately document heart rate over a full day.
For bradycardias linked to external factors like medication use, a simple review or adjustment by the treating physician is often sufficient to resolve the issue.
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