Bradycardia is an unnaturally slow heart rate. This means that an adult heart beats less than 60 times per minute when resting. For some people this isn’t a problem. For others this means that the body, including the brain, isn’t receiving the necessary amount of oxygen and nutrients.
When bradycardia is a problem the symptoms can include fainting, dizziness, fatigue, difficulty catching the breath, pains in the chest, confusion and weakness. Bradycardia can have have a variety of causes. The heart can be damaged from aging, disease or a heart attack. The person might have been born with a heart defect that causes his or her heart to beat too slowly. High blood pressure, sleep apnea, rheumatic fever, an abnormal amount of iron in the body, medicines, infection in the heart, hypothyroidism or an electrolyte imbalance can all be causes of bradycardia.
A person who has dangerous bradycardia can be subject to repeated fainting, heart failure or sudden death.
Heart block can also cause bradycardia. The heart is an organ that runs on its own electricity. Sometimes the electrical signals in the upper chambers of the heart, the atria, don’t get through to the lower chambers in the heart, the ventricles. This is called a heart block. Heart blocks are classified by degrees.
In a first degree heart block, the ventricles do receive signals from the atria but they’re slowed down a very small amount. First degree heart block usually doesn’t need treatment nor does it cause symptoms.
In second degree heart block, the ventricles aren’t getting all the signals from the atria. This causes the heart to slow down or beat in an irregular manner.
In a third degree heart block, the ventricles aren’t receiving any signals from the atria, so other areas of the heart need to send their own signals to the ventricles to keep the heart going. But this is inefficient and results in bradycardia and an irregular heart beat.
Another type of heart block is the bundle branch block. There are right and left-handed bundle branches near the end of the heart’s electrical pathways and electrical impulses can also be blocked there as well. The severity of this sort of block is dependent on whether one or both of the bundle branches is blocked, if the patient is suffering from another type of heart block and if the heart is damaged.