Heart rhythm abnormalities

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.

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

hypothyroidism

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. 

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 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

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