What causes slow heart rate? 13 possible conditions
The heart rate is the number of beats (rhythmic contractions) per minute of the heart (the muscular organ in the center of the chest that maintains circulation of the blood) and is a measure of cardiac activity. Read more
What Is a “Slow” Heart Rate?
Your heart rate is the number of beats (rhythmic contractions) per minute of your heart. Your heart is the muscular organ, located in the chest, behind and to the left of the breastbone that maintains circulation of the blood. Heart rate is a measure of cardiac activity.
Heart rate is one of the vital signs. Vital signs like body temperature, pulse, breathing rate, and blood pressure provide information about a person’s state of health. Any abnormality of these signs can offer diagnostic clues.
A slow heart rate is considered anything slower than 50 beats per minute for an adult or child at rest.
Alternative names for this condition include:
- heart rate decreased
- heartbeats decreased
- low heart rate
- decreased heart rate
- pulse slow
- pulse rate decreased
- slow heartbeat
- slow pulse
Understanding Your Heart Rate by the Numbers
You can measure your heart rate. First, find your heart rate by holding a finger to the radial artery at the wrist. Other places it can be measured are at the neck (carotid artery), the groin (femoral artery), and the feet (dorsalis pedis and posterior tibial arteries). Then, count the number of beats per minute while you are resting.
Here are some numbers to keep in mind:
- The resting adult heart rate is normally 60 to 100 beats per minute.
- Athletes or people on certain medications may have a lower resting normal rate.
- The normal heart rate for children aged 1 to 8 years is 80 to 100 beats per minute.
- The normal heart rate for infants age 1 to 12 months is 100 to 120 beats per minute.
- The normal heart rate for newborns (under 1 month old) is 120 to 160 beats per minute.
Problems That Can Accompany a Slow Heart Rate
Your heart rate should be strong and regular without any missed beats. If it’s beating slower than the normal rate, it might indicate a medical problem. Fainting, dizziness, loss of consciousness, weakness, and fatigue can accompany a slow heart rate.
In some cases, a slow heart rate is an indication of an extremely healthy heart. Athletes, for instance, often have lower than normal resting heart rates because their heart is strong and doesn’t have to work as hard to pump blood throughout the body. However, when a slower heart rate is uncommon and/or accompanied by other symptoms, it could be a sign of something more serious.
Potential Underlying Causes of a Slow Heart Rate
A thorough medical evaluation is necessary to determine the cause of a slow heart rate. An electrocardiogram (EKG or ECG), laboratory tests, and other diagnostic studies may be done.
Potential medical causes of a slow heart rate include:
- abnormal heart rhythms
- anorexia nervosa
- autonomic dysreflexia
- autonomic neuropathy
- congestive cardiomyopathy
- heart attack
- elevated potassium
- intracerebral hemorrhage
- marine animal stings or bites
- side effects of medications
- subarachnoid hemorrhage
- sick sinus syndrome
- AV node damage
Treating the Cause of a Slow Heart Rate
Treatment depends on the underlying condition. If slow heart rate is due to the effect of medication or toxic exposure, this must be treated medically. An external device (pacemaker) implanted into the chest to stimulate heartbeats is the preferred treatment for certain types of bradycardia.
Because a low heart rate could indicate medical problems, make an appointment with your doctor if you notice any changes in your heart rate, especially if the changes are accompanied by other symptoms.
Recognizing a Potential Emergency Situation
In certain situations, a slow heart rate could indicate a medical emergency. The following symptoms can be serious:
- loss of consciousness
- chest pain
- passing out or fainting
- shortness of breath
- arm pain
- jaw pain
- severe headache
- blindness or visual change
- abdominal pain
- pallor (pale skin)
- cyanosis (bluish skin color)
If you have any of these symptoms and a change in your heart rate, call 911.
- All about heart rate (pulse). (2014, September 30). Retrieved from http://www.heart.org/HEARTORG/Conditions/More/MyHeartandStrokeNews/All-About-Heart-Rate-Pulse_UCM_438850_Article.jsp
- Laskowski, E. (2012, September 29). What’s a normal resting heart rate? Retrieved from http://www.mayoclinic.com/health/heart-rate/AN01906
- Slow heartbeat. (n.d.). Retrieved from http://www.hrsonline.org/Patient-Resources/Symptoms-Diagnosis/Slow-Heartbeat
- Target heart rates. (2015, January 8). Retrieved from http://www.heart.org/HEARTORG/GettingHealthy/PhysicalActivity/Target-Heart-Rates_UCM_434341_Article.jsp
See a list of possible causes in order from the most common to the least.
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