Bradycardia: Definition, Causes, Symptoms & Treatment Video

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  • 0:06 A Slow Heart Rate
  • 0:36 What Is Bradycardia?
  • 1:43 Causes of Bradycardia
  • 3:36 Signs, Symptoms, & Diagnostics
  • 5:13 Treatment Options
  • 5:50 Lesson Summary
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Lesson Transcript
Instructor: Artem Cheprasov
Being slow is usually not a very good thing, and frankly, it's usually not good when your heart is slow either. Therefore, we will discuss something known as bradycardia, why it occurs, and how it may be diagnosed in this lesson.

A Slow Heart Rate

Elite athletes are some of the strongest and fastest people on this planet. Their speed, be it on land or water, is in direct opposition to the speed of their heart at rest. Sure, everyone's heart slows down when they are relaxed and resting. But the speed of an athlete's heart oftentimes beats much slower than normal, but that's normal for them. However, sometimes an abnormally slow heart rate is an indicator of a health problem that needs to be looked into.

What Is Bradycardia?

An abnormally slow heart rate, less than 60 beats per minute, is more technically known as bradycardia. I use the word 'abnormally' a bit more loosely in this definition than I usually do because, again, while an elite athlete's heart is by typical standards abnormally slow, it's actually completely normal for them. Anyways, the suffix 'brady-' refers to something that is 'slow,' and 'cardia' I think obviously refers to the 'heart.'

If you're a fan of American football, then remembering my introductory example and the meaning of 'brady'cardia won't be difficult since Tom Brady is an elite athlete who probably has bradycardia at rest. Maybe one day he'll watch this video and confirm whether my assumption is correct or not. And if you're not a fan of Tom Brady (sorry Tom) or have no idea who he is, then think about the fact that 'brady' rhymes with 'old lady,' and no offense to old ladies, but they kind of move slower than normal.

Causes of Bradycardia

Bradycardia can occur for a wide variety of reasons. One potential cause is hypothyroidism. This is when your body doesn't produce enough thyroid hormone. This hormone is like an energy drink to an athlete - it helps them think and move faster. Without thyroid hormone, your heart doesn't get that shot of energy and doesn't beat as fast.

Sick sinus syndrome, a group of disorders where the sinoatrial node fails to generate an appropriate heart rate, is another cause of bradycardia. The sinoatrial node is the pacemaker of the heart that sets the pace (or plays) of the heart. It's like the star quarterback of the team. If it's sick and not working right, none of the plays will go off correctly during a game.

Another possibility for bradycardia is damage to the heart muscle from something such as a myocardial infarction, which is the death of heart tissue as a result of improper blood flow to it. More commonly, we just call this a heart attack. When the blood supply is cut off to the heart, the heart muscle doesn't receive oxygen, resulting in injury. So, just like an injured athlete slows down, so too does an injured heart.

Another cause of bradycardia is hypertension, or high blood pressure. High blood pressure makes it very difficult for your heart to push blood out into circulation and causes a reflex in your body (called reflex bradycardia) that slows down the heart in order to try and lower the blood pressure. Think about linebackers who come up against an opponent. As they do so, they slow down to almost a dead stop due to the other player's resistance to move. Well, if your heart is pushing hard against the resistance of high blood pressure, it may slow down as well.

Signs, Symptoms, and Diagnostics

Speaking of a dead stop, bradycardia could cause your death as a result of many other reasons, such as infection, electrolyte disorders, certain medications, and many more. That's why it's important to look out for signs associated with bradycardia. Signs and symptoms of pathologic bradycardia are usually seen only when the heart rate drops below 50 beats per minute. These important clues include:

  • Fainting, or syncope
  • Dizziness
  • Fatigue
  • Shortness of breath

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