The alphabet soup of arrhythmias.

Over the last nine months, several friends have experienced unusual heart beats.  Maybe they felt like their hearts were beating too fast, or even missing a beat.  They did the smart thing and went to see the doctor.  They were instructed to wear event monitors for a while which would track their heart beats and enabled them to register any unusual feelings that they experienced during the time that they were wearing these monitors. 

So what was going on with them?  I’d like to be able to tell you in plain English.  But just like the legal profession, the medical profession uses peculiar terms that the lay person does not easily understand.  They tend to use short hand terms or acronyms to describe or define medical conditions.  As you may recall, a previous post covered how the short hand term “A Fib” is used to define a heart condition that indicates a racing heart.  
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I can certainly relate to the fact that it is sometimes easier to use these short hand terms rather than to continue to say atrial fibrillation, a term which doesn’t necessarily roll easily off the tongue.  But their use can sometimes result in perplexing conversations.  For example, what happens when the short hand term that is used also has a meaning that isn’t necessarily related to the heart?  It can lead to some real confusion or in some instances, anxiety when these peculiar terms start showing up in medical reports or in conversations with the doctors. 

Here are two examples to illustrate what I mean:  PVC and PAC.   Now, if you lived in the law enforcement world for any length of time, PVC could actually be a component in an improvised explosive device (IED) otherwise known as a bomb.  And if you watch CNN, Fox News, MSNBC and all the cable network news channels, you probably are more familiar with PAC being the term of art for a political action committee. 

Can you guess how these non-cardio short hand terms might impact your heart?  For example, maybe an explosive device or political debate might well cause a heart to beat abnormally.  But for the cardiologist, the term PVC means premature ventricular contractions, and the term PAC means premature atrial contraction.  When I first heard one of these terms, I wondered why doctors couldn’t just simplify the matter by referring to them as early heartbeats. 

But what I was missing was the fact that the term also defines the part of the heart that causes the early beat to occur.  The thing that makes a PAC different from a PVC is that this premature heartbeat occurs in the upper chamber of the heart, also referred to as the atria or the upper pumping chambers of the heart.  The PVC occurs in the ventricles, or the lower pumping chambers of the heart. 

It isn’t just the fact that the heartbeats are early that makes them similar.  PVCs and PACs share the distinction that they fall within the category of a heart arrhythmia.  And what does that term mean?  Well according to the National Heart, Lung and Blood Institute webpage of the National Institutes of Health website: 

• “An arrhythmia is a problem with the rate or rhythm of the heartbeat. During an arrhythmia, the heart can beat too fast, too slowly, or with an irregular rhythm. When a heart beats too fast, the condition is called tachycardia. When a heart beats too slowly, the condition is called bradycardia.   Arrhythmia is caused by changes in heart tissue and activity or in the electrical signals that control your heartbeat. These changes can be caused by damage from disease, injury, or genetics. Often there are no symptoms, but some people feel an irregular heartbeat. You may feel faint or dizzy or have difficulty breathing.”

I am of course familiar with Bradycardia, as a pacemaker now controls my heart beat to assure that it is not too slow.  I have also heard the term arrhythmia throughout the time that I have been diagnosed with heart failure.  But I never looked into the definition until I started to write this post.  Then I found not only the website listed above but also a website for the Texas Heart Institute.  They have an article that categorizes the various types of arrhythmias.  Trust me, there are a lot of them. 

The article seems to break the categories down into two main sections:  ventricular arrhythmias and superventricular arrhythmias.  When I read the definitions, I realized that superventricular actually means the area above the two ventricle chambers of the heart, which includes the two atrial chambers.  So this means that the Premature Atrial Contraction (or PAC) can also be referred to as the premature superventricular contraction.  Are you confused yet?

In addition to PVCs and PACs, here are some other arrhythmias listed in the Texas Heart Institute article. 
Superventricular tachycardia (SVT) is a rapid, regular heart rate where the heart beats anywhere from 150-250 times per minute in the atria.   Then there is the Wolff-Parkinson-White (WPW) syndrome which is caused by extra muscle pathways between the atria and the ventricles. The pathways cause the electrical signals to arrive at the ventricles too soon, and the signals are sent back to the atria. The result is a very fast heart rate.  Or you can have postural orthostatic tachycardia syndrome (POTS).  This is a syndrome that can occur when one stands up.  In most cases, a person’s heart rate increases and the blood vessels in the lower part of the body tighten. But In some people, this does not happen, affecting their ability to stand or remain standing. This is called orthostatic intolerance.

The article lists other types of arrhythmias, but I have chosen to just include the alphabet soup ones.  But if you want more information on all the varieties that are out there, I encourage you to visit the Texas Heart Institute website and look for the arrhythmia page.
 
The Heart Foundation website (an organization in Australia) provides a good list of possible causes for arrhtymias.  It says that they are caused by problems in the heart electrical system that can happen because of heart disease or other things like:

• Blocked electrical signals, abnormal electrical signal pathways, or irritable heart cells that send out signals when they shouldn’t
• Some medicines or stimulants like caffeine, nicotine or alcohol
• A coronary artery spasm (called Prinzmetal agina). .  This is a temporary discomfort or pain caused by a spasm (constriction in one or more of your coronary arteries which can block the blood supply to your heart muscle
• Or sometimes there is no known cause

I love the explanation that talks about the irritable heart cells.  I figure that has to be my issue.  Chalk it up to my impatient heart getting cranky because I have things to do but my heart’s electrical system just won’t keep up with my agenda!

How will the doctor figure out if you have an arrhtymia?  The following are the most common tests according to the webpage for the National Heart, Lung and Blood Institute:

• Blood tests to check the level of certain substances in the blood (such as potassium)
• A cardiac catheterization to  see if you have complications from heart disease
• A Chest x ray to see if your heart is larger than normal
• Echocardiography to inform the doctor of the size and shape of your heart and how well it is working.
• An EKG to see how fast the heart is beating and if the rhythm is steady or irregular.
• An electrophysiology study to look at the electrical activity of the heart.
• A holter or event monitor to record the heart’s electrical activity over long periods of time.
• An implantable loop recorder to detect abnormal heart rhythm.
• A sleep study to see if sleep apnea is causing your arrhythmia
• A stress test or exercise stress test to detect arrhythmias that happen while the heart is working hard and beating fast.
• Tilt table testing to help find the cause of fainting spells.

Obviously there are a lot of tools in the box to help the doctor figure out why your heart is beating at an irregular, and maybe even deadly rate.

So what happened to my friends?  Nothing catastrophic or even unusual. One was told that she was experiencing a premature atrial heartbeat.  Both were dismissed from return visits to the heart doctor, as their heart beat issues were harmless.  But I believe they were reassured that they got clean bills of health. This reinforces for me what is a wise course of action should you ever suspect that you’re having a palpitation or something else that signals a heart electrical issue.  Most of us who have these are not doctors, and even if we were, well you need someone else to objectively assess whether what is happening to you is serious or harmless when it comes to matters of the heart.

​So to summarize in a manner that is as simple as ABC, when your heart beats lack regularity, then you should pay attention.  Frankly, in my experience anything that makes you conscious of your heart is disconcerting.  It is worth the time to go to a doctor who knows about hearts and check it out.  If you need a fix, it is more economical to get it fixed now than to have it turn into a bigger problem such as cardiomyopathy. 

My parting advice to those who are experiencing the ABCs of arrhythmias and palpitations is this:  don’t miss a beat – get thee to a cardiologist ASAP.