What Is Bradycardia?

Bradycardia is a type of heart rhythm. It means that your heart is beating slower than normal. So what does this really mean? What causes it? How might this contribute to heart failure? Here’s all you need to know.

Basic anatomy

Every heartbeat is started by an electrical impulse. This electrical impulse is created by specialized cells within your heart. They are inside the right atria of your heart and are called the Sino-Atrial (SA) Node. This is often referred to as your natural pacemaker. Each electrical impulse of your heart is created by your natural pacemaker. When your natural pacemaker is pacing your heart, this is called “sinus.”¹

What is bradycardia?

A normal heart rate is 60-100 beats per minute (BPM). Anything greater than 100 is considered tachycardia. This is a heart rhythm we can cover in a future post. Anything less than 60 is considered bradycardia. This is what we will define right here in this article.

Brady is a Greek term for slow. Cardio means “relating to the heart.” Put these two terms together, and you get “Brady-cardia” which of course means “slow heart rate.”^2-4

What causes bradycardia?

There are many causes, almost too many to list in a single post. Some include trauma, heart disease, heart attack, sick sinus syndrome (defined below), and surgery to repair congenital (you are born with it) heart disease. It may also be caused by sleep apnea, low oxygen levels, and various medicines. This is not even close to a complete list.²

What are the symptoms of bradycardia?

Most people with bradycardia experience no symptoms. However, sometimes the heart rate gets too slow, and this may result in symptoms. A good example is when your heart rate is less than 40 BPM. When this happens, it may not be pumping out enough oxygenated blood to adequately feed organs like your brain. This can cause you to feel lightheaded or dizzy. It may cause you to faint or pass out. A fancy term for fainting is syncope or having a syncopal episode.^2,5

Other symptoms include confusion, fatigue, shortness of breath at rest, and shortness of breath with exertion. In rare instances, If you already have angina (chest pain) or heart failure, it may cause these to become worse. If it is not treated, it may cause heart failure. It may cause your heart to stop (cardiac arrest).^2-5

However, the goal of treatment is to prevent heart failure and cardiac arrest from ever happening. This is why it is so important to seek medical attention if you experience any of the above-listed symptoms.

Types of bradycardia

There are different types of bradycardia and each may have different causes.

Sinus bradycardia

This means your heart is beating less than 60 BPM. Sinus bradycardia usually causes no symptoms and it may be perfectly normal. For instance, some people who exercise a lot may develop sinus bradycardia. This is because vigorous exercise makes your heart a stronger pump and fewer beats are required to pump the same amount of blood.^1,6-8

More symptoms

Sometimes it may cause symptoms, but this usually only happens if your heart rate is very low, such as less than 40 BPM. When this happens, your heart may not be pumping out enough blood fast enough to supply your brain with oxygen. In cases like this, medical treatment is necessary. I will discuss potential treatments below.1,6

More terms to know

Heart block

This is an interesting phenomenon. Your natural pacemaker sets off an electrical impulse, but this impulse is blocked which causes your heart to skip a beat or two or three. Because beats are skipped, your heart rate falls to less than 60BPM (bradycardia).¹

There are different types of heart blocks. Some are more severe than others. In a future post, I can go over the different types of blocks if you want. For the sake of this post, know that some heart blocks can cause bradycardia. This may sometimes cause symptoms and may require immediate treatment.^1,6

Sinus pause (sinus arrest)

Here the natural pacemaker fails to initiate a beat or two, so it causes a pause for 2 seconds or greater. This causes the heart rate to be too low. Sometimes it is just temporary and needs no further treatment. Sometimes it is prolonged and causes no symptoms. Although, in some cases, it may cause symptoms requiring treatment.^9-10

Sick sinus syndrome (sinus node dysfunction)

This is a dysfunction of the SA node. It may cause various abnormal heart rhythms and may cause your heart rate to not increase appropriately when you are exerting yourself. This can cause you to become winded with exertion. It may also cause other symptoms as described above. It usually only occurs in older people with a diagnosis of heart disease.^1,2,6,9

Tachy-Brady Syndrome

This occurs in some patients with sick sinus syndrome and is when the heart rhythm alternates between tachycardia and bradycardia. Sometimes the first reported symptom is fainting (syncope) which is often how it is diagnosed. That said, many symptoms develop gradually, and might be brushed off due to aging. In these cases, it may take longer to get a proper diagnosis.^6,9

How is bradycardia diagnosed?

The most common way is by having a simple test called an EKG. This is a quick test that only takes a few minutes. Similar tests are aZio Patch and Holter monitors. This is where your EKG is monitored for 2-14 days. Other tests can help diagnose bradycardia as well.^2,11

What is the treatment for bradycardia?

If you are feeling no symptoms, your doctor may decide no treatment is indicated. However, if you are experiencing symptoms, your doctor may recommend treatment. Initial treatment may involve tests to see what is causing the slow rate. Sometimes solving the problem will return your heart rate to normal. Treatment may also involve medicine to speed up your heart. A doctor may also recommend a pacemaker. These are neat little devices that keep your heart pacing at a healthy rate.^6,12