Bradycardia: Extremely Poor Blood Circulation Can Kill
The average person's resting heart rate typically ranges between 60-85 beats per minute. However, when someone's heart rate drops below 40 bpm the person is said to be suffering from bradycardia and the situation becomes a a medical issue that needs to be addressed. In practice, the actual cut-off varies by individual as even a heart rate of 60 bpm can be considered bradycardia for someone whose heart can't circulate blood adequately. That is why medical intervention is required if bradycardia is suspected.
Bradycardia is usually caused by some kind of illness or a malfunction of the heart's electrical system. When this occurs blood flow is reduced to vital organs, such as the brain, which can cause dizziness and fainting. Reduced blood flow can also have a compounding effect as a heart that doesn't receive enough blood flow can't work properly which can further reduce blood flow.
Not Always Bad
Usually a low resting heart rate is not a problem if it is the results of a very strong, efficient, and healthy heart. Professional endurance athletes, such as marathoners, triathletes, and decathletes typically have such hearts and can have a resting heart rate as low as 35-40 bpm. The reason for this 'healthy' low heart rate is the heart is able to pump the same amount of blood with fewer beats. Generally, the volume of each pump is higher when someone is fit. As an analogy, imagine your neighbor having a bigger snow shovel than you. They will be able to clear their driveway with fewer shovel-fulls. However, they must be fit and strong enough to push and lift that extra snow in their shovel.
Symptoms of bradycardia can include dizziness or fainting; feeling out of breath while resting; and getting tired easily from mild activity. If the brain is affected enough by the decreased blood and oxygen flow, brain impairment, such as memory problems, can also occur. If you have any of these symptoms you should seek medical help immediately. A quick and accurate diagnosis can prevent further, and possibly permanent, damage to the heart.
There are various possible causes of bradycardia:
- A heart attack. A mild one perhaps that went undiagnosed which has now resulted in damaged cardiac muscle.
- Some kind of infection which has damaged the heart muscle.
- Hypothyroidism, which is the unusually low production of hormones by the thyroid gland.
- Severe electrolyte imbalance. The heart requires certain nutrients to be able to function properly, e.g. potassium, sodium, etc. Without these the muscles cannot contract efficiently.
- Hypertension, also called high blood pressure. Although this may sound counter-intuitive, it can affect and result in low heart rate.
- Medications that have an unintended side-effect.
Diagnosis by a cardiologist can include:
- Heart rate measurement under different conditions.
- Measuring blood pressure.
- A blood test to investigate electrolyte imbalance.
- An ECG (Electrocardiogram) where the heart's electrical activity is monitored.
Bradycardia isn't a condition that is treatable with typical first aid techniques. If not treated, bradycardia can progress to the point where unconsciousness, respiratory difficulty, respiratory arrest, and eventually cardiac arrest will occur. Treatment usually includes medications and/or a pacemaker. A pacemaker is a small implanted electrical device which attaches to the heart muscle and helps maintain normal heart rate. It is usually implanted on the upper left chest area.
Bradycardia can also accompany a condition known as arrhythmia, which is an irregular heart beat. Meaning, sometimes it is too fast while at other times too slow.