What is a Cardioversion?

I am a respiratory therapist. My job in the hospital is to take care of your airway. I am often on standby during cardioversions. I have never had one done, although I have an inside take on what it’s like. So, here’s what to know about cardioversions.

When are cardioversions needed?

Your normal pacemaker sends an electrical current through your heart. It’s just enough of a current to cause your heart to beat normally. The electrical current causes your heart muscle to contract. This in essence squeezes your heart to force blood through your body.

Sometimes other areas of your heart become excitable. These areas repeatedly send an electrical current through your heart causing it to beat fast and abnormally. This is called arrhythmia. When this happens, the heartbeats are not as effective.

This can cause you to have a funny feeling (palpitations) in your chest. It can cause you to feel dizzy or short of breath. Two common arrhythmias are atrial fibrillation (AFib) and supraventricular tachycardia (SVT). Another arrhythmia that can be converted is atrial flutter. You can read more about heart rhythms in my post, “7 Heart Rhythms Worth Knowing.”

Sometimes these arrhythmias go away on their own. They begin, they make you feel funny, but they just go away after a few minutes. In many instances, a cardiologist may consider this normal, and no treatment is required.

However, when the arrhythmia persists, treatment is needed. Your doctor may order cardioversion. Some arrhythmias require emergent cardioversion. Other cardioversions are non-emergent and can be scheduled.

What is a cardioversion?

There are two types of cardioversions:

  • Chemical: a medicine is used to convert your heart to a normal rhythm.
  • Electrical: electricity is used to convert your heart to a normal rhythm.

Chemical cardioversion

There are medicines that can be prescribed to reverse these arrhythmias. One medicine called adenosine is injected into your vein via an IV. This is a treatment for SVT. Other medicines may be used for atrial fibrillation.1

What adenosine does is stop your heart for a few seconds. This can feel a bit awkward and maybe somewhat scary. But, the nurse giving it to you should assure you it will just be for a few short seconds. Pausing your heart this way allows your heart to reset itself. When effective it restores (converts) your heart to normal heart rhythm.1

Many times I have seen this work. Although, sometimes it doesn’t work. When this happens electrical cardioversion may be ordered. Chemical cardioversions are usually tried first as they do not require any sedation and are generally painless.1

Electrical cardioversion

This involves placing electrodes on your chest. A jolt of electricity is sent through these electrodes. This can prove helpful for converting your heart rhythm back to normal.2

It can be painful. That’s why it’s done in a controlled setting where you can be given medicine to put you to sleep. This makes it so you don’t feel the shock and have no memory of it. This is called “conscious sedation.” It’s similar to what happens at the dentist's office. Your dentist sedates you for a certain dental procedure. This way you don’t feel it and have no memory of the procedure when it’s done. It's a good thing.2

So conscious sedation is where medicine is used to put you to sleep which is is why I am present. Usually, when I’m there it’s because you are in the emergency room (ER), although cardioversions can also be done in other areas of the hospital. When this is the case, an anesthesiologist may play the role I play in the ER. Of course, an anesthesiologist is also a doctor who can also give medicine.2

Breath support

Anyway, in the ER you get me. A doctor is present. A nurse is present. And I am present. A doctor orders the medicine. A nurse injects it into your IV. I am there because the medicine may cause you to breathe shallowly. In rare instances, it can cause you to stop breathing for a few minutes. So, my job is to breathe for you should you stop.

So, I am there just in case I’m needed. I have a bag that I hook up to oxygen. If you should stop breathing I can put the mask over your mouth and nose and give you some breaths. I assist your breathing this way until the medicine starts to wear off and you start breathing on your own.

Before the procedure, a nurse will put an IV in you. Pads will be placed on the left side of your chest (over your heart) and the backside of your heart (behind your heart). I will place a nasal cannula into your nose. This allows you to receive a low flow of oxygen. The medicine can cause you to breathe shallow, so inhaling some extra oxygen makes sure your oxygen levels stay normal.

I also place a big, bulky thing in your nose over the nasal cannula. This weird thing is to monitor your carbon dioxide (CO2) levels. CO2 is a waste product that you exhale. If your breathing becomes ineffective, your CO2 level drops. This is a sign for me to assist you until you wake up.

You are usually back awake in a few minutes after the procedure.

Restoring normal heart rhythm

Cardioversion is useful for certain abnormal heart rhythms. Chemical cardioversions involve medicine. Electrical cardioversions involve electricity. Both these methods are helpful for converting abnormal rhythms back to normal rhythms. Have you ever experienced cardioversion? Share your thoughts in the comments below.

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