It’s common to hear someone say their heart is “racing” when they’re excited, nervous or recovering from strenuous exercise. But your rarely hear about a heart rate that is slower than normal — a condition called bradycardia. What causes a slow heart rate and is it a reason for concern?
In this video, San Diego Health host Susan Taylor talks with Poulina Uddin, MD, a cardiologist at Scripps Clinic Anderson Medical Pavilion in La Jolla, about bradycardia symptoms, causes and treatments.
In general, adults with bradycardia have a resting heart rate that falls below 60 beats per minute, but this can vary with fitness level, age and other factors. People who are very fit, such as some athletes, may have a low resting heart rate. Heart rate also tends to slow down a bit as part of the natural aging process, so bradycardia is more common among elderly people.
“The natural aging process of the heart’s electrical wiring can also cause people to skip some beats,” says Dr. Uddin. “So when we check the heart rate, it may actually be too slow or people are skipping beats, which is known as arrhythmia or irregular heartbeat.”
In addition, causes of a slow heart rate may include:
- Problems with the sinoatrial (SA) node, which acts as the heart’s pacemaker
- Problems with the heart’s conduction pathways, which allow electrical impulses to pass from the upper chamber to the lower chamber
- Problems with the metabolic system, which controls how the body uses energy (such as an underactive thyroid)
- Damage to the heart from heart disease or a heart attack
- Heart medications that cause slow heart rate
- People are rarely born with conditions that cause a slow heart rate
Dr. Uddin says that a slow heart rate usually is a concern only if it causes symptoms. Because a slow heart rate can disrupt the flow of blood to the brain, people with bradycardia may experience symptoms such as:
- Feeling weak
- Dizziness or lightheadedness
- Fainting or almost fainting
- Shortness of breath
- Difficulty exercising
Bradycardia is diagnosed with a heart rate test or electrocardiogram (EKG). If you do have a slow heart rate that is causing symptoms, your doctor may recommend monitoring your heart to determine if it is truly beating too slowly or if you are skipping beats due to arrythmia. There are several ways to track your heart’s activity.
“You can wear an external heart monitor for one or two weeks, up to 30 days, to let us know what your heart rate is doing over time,” Dr. Uddin says. “Depending on the situation, we also have longer-term monitors that are implanted under the skin and stay in for several years. They can send a notification to your doctor's office if the heart rate is too slow or too fast.”
If your bradycardia only happens occasionally or is mild, you may not need treatment. Instead, your doctor may monitor your condition to see if it changes. Bradycardia caused metabolic conditions may be treated with medication or hormone therapy.
Serious bradycardia is usually treated with a pacemaker. This tiny device is implanted into the chest to regulate the heart’s rhythm and correct it if necessary. The surgeon implants the device using minimally invasive techniques; most patients spend one night in the hospital followed by two weeks of modified activity during recovery.
“If you are feeling tired, have no energy or find yourself unable to exercise without getting unusually fatigued or out of breath, make an appointment with your doctor,” says Dr. Uddin. “Other conditions can cause similar symptoms, so it’s important to determine what is causing them. If fainting or other symptoms occur frequently or are severe, it’s a good idea to get checked out at an emergency room.”