During our lives, we have a one in three chance of developing a heart rhythm abnormality. In cardiology, the field of electrophysiology focuses on heart rhythm disturbances—or heart arrhythmias as they are called. While the heart muscle may not be damaged, a heart arrhythmia can cause serious functional problems.
Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy
With a normal range of 60 to 100 beats per minute, on any given day, our hearts beat an average of 100,000 times. For a person living to the age of 78, that is about 3.3 billion heartbeats in a lifetime. A change in this normal heart rate is referred to broadly as bradycardia or tachycardia.
When the heartbeat is too slow, the condition is called bradycardia. Tachycardia exists when the heartbeat is too fast. These two arrhythmia conditions have different causes, symptoms and treatments.
“If you feel an irregular heart beat and you’re experiencing symptoms of dizziness, palpitations or passing out, then it is most likely one type of arrhythmia,” says Cleveland Clinic Cardiologist Walid Saliba, MD. “When this happens, you need to be evaluated by a physician right away.”
About bradycardia, the slow beat
A slowed heart rate varies greatly from person to person. Bradycardia is defined as a heartbeat below 60 beats per minute, however, it does not necessarily need to be treated unless it is associated with symptoms. A rate that is too slow for a person will reduce the amount of blood and oxygen to vital organs, which results in various symptoms such as shortness of breath, a drop in blood pressure, extreme fatigue, decreased exercise capacity, dizziness and fainting.
Causes for bradycardia include:
- degenerative disease of the electrical system of the heart that comes with age
- electrolyte imbalances
- side effects from blood pressure medications
- coronary diseases that damage the electrical system of the heart
Treatments for bradycardia often focus on managing the underlying conditions that are causing the slow heart rate; sometimes a pacemaker will be implanted. “Many times a slow heart beat does not need to be treated,” says Dr. Saliba, “unless it is associated with ongoing symptoms.”
About tachycardia, the fast beat
Tachycardia is a rapid heart rate that is faster than 100 beats per minute, and it causes the heart to work too hard. This means that the heart does not have enough time to fill and that not enough blood is being pumped forward. This results in symptoms including palpitations, chest pain, dizziness and fainting. Sometimes patients have no symptoms aside from the rapid heart rate.
Causes for tachycardia can be:
- congenital abnormalities
- heart disease (such as weakness of the heart muscle, heart failure or heart attack)
- some types of lung diseases
It can also be caused by fever, dehydration, excessive caffeine (from energy drinks, etc.), substance abuse or a reaction to a medication.
Prior to any treatment, the doctor will look for underlying causes for the fast heart rate. Common treatments for tachycardia, include anti-arrhythmic medications to slow down the heart and cardioversion, which is an electric shock used to reset the normal rhythm of the heart.
Dr. Saliba stresses, “If you have fast or irregular heartbeats, you also will want to find out if you have a condition called atrial fibrillation—not just an arrhythmia. If so, you have a greater risk for a stroke and need to be treated.”