Electric Shock for Atrial Fibrillation: Is it Dangerous?
_"You want to do what?" she asked.
"Because you have Atrial Fibrillation, I'd like to schedule you for an electrical cardioversion," I said.
A middle-aged woman with Atrial Fibrillation was in my office. She was suffering with symptoms of fatigue and breathlessness. Her heart was racing at times and it was difficult to get controlled. I felt should would best be served by getting her heart back into the normal rhythm.
One way to do this is by giving a very mild electrical shock to the patient while they are under anesthesia. Electrical Cardioversion is the name given to this procedure.
Many patients wonder, "Is this Dangerous?
It is a frequent question that concerns many patients. Most people have watched movies or heard horrifying stories of people who have been electrocuted. So it is understandable that that you might have a question if your cardiologist brings up the idea of scheduling you for this procedure.
First of all you should know that Electrical Cardioversion is very safe.
Although medical studies have shown a minimal release of muscle enzymes from the heart with electrical cardioversion and rare need of temporary pacing, serious complications are unusual. In my own experience of doing this procedure for over 20 years, I have never had a serious complication.
Perhaps the biggest worry is the release of blood clots from a pouch in the heart called the Left Atrial Appendage. If a person has been in Atrial Fibrillation for more than 48 hours it is necessary that they be placed on warfarin (Coumadin ®) prior to the cardioversion.
The current recommendation from the American College of Cardiology is to anticoagulate patients with chronic AF for three to four weeks prior and for at least four weeks following cardioversion. A different approach is to perform a TEE (Transesophageal Echocardiogram) to view the Left Atrial Appendage to make sure no clots are present before performing the procedure.
OK, I hope I've alleviated your fears about a cardioversion.
Why would my doctor want to do this procedure?
The next issue that you might want to know is why is your heart doctor would want to perform this procedure? Why would it be indicated?
You should know that cardiologists consider 2 different treatment strategies when approaching patients with atrial fibrillation.
Rate Control vs Rhythm Control
Atrial Fibrillation is a heart condition where the heart rhythm is abnormal. Rather than being controlled by the heart's typical pacemaker cells- called the "Sinus Node" the rhythm is chaotic. The electrical pattern is very marked irregular.
Rhythm Control: One approach in treating Atrial Fibrillation is controlling the rhythm, trying to get the heart back in the normal regular rhythm. Cardiologists call this rhythm control.
Controlling the symptoms caused by AF is the reason most cardiologists recommend Rhythm Control. Returning a person's heart to a normal rhythm will reduce symptoms for the vast majority of people.
Medical studies have not shown any long-term advantage as far as complications are concerned when the rhythm is controlled, but complaints such as palpitations, shortness of breath or poor exercise ability often improve. The vast majority of patients feel better if they can be returned to normal rhythm.
Rate Control: Atrial Fibrillation is also a very rapid heart rhythm. The upper chambers produce fibrillatory waves at a rate of 350-600/minute. Human beings cannot tolerate such a rapid heart rate. The body has a natural protective mechanism with a rate lowering "junction box" called the AV node. The AV Node only allows the heart to beat around 200 times a minute.
Rapid heart rates can lead to significant symptoms of breathlessness, fatigue, and may even lead to congestive heart failure. Rapid Atrial Fibrillation can also cause chest pain, light headedness and can even lead to damage of the heart muscle something called, a " tachycardia-mediated cardiomyopathy." Rate Control is another way to treat patients with Atrial Fibrillation.
Electrical Cardioversion is used for Rhythm Control:
Electrical cardioversion is used for heart rhythm control. It is very effective when used in conjunction with medications for returning a person to the normal heart rhythm. This is especially true if the heart is fairly normal. By this I mean if the heart chambers are not overly enlarged, and the heart pumps well.
If the heart is excessively enlarged or very weakened, it may be difficult to keep a patient in the normal rhythm.
Most patients prefer to be in the normal rhythm. They generally feel better. The risk of stroke may not actually be lower. Two large medical studies called AFFIRM and RACE showed that strokes are frequent even in people to are placed back in the normal rhythm. These stokes occurred after warfarin/Coumadin ® had been stopped or when the test of the blood thinning level (International Normalized Ratio (INR)) was below the recommended range.
Because of this people who are high-risk should consider continuing anticoagulation for some time even if they are in normal rhythm. They should also consider having a heart monitor that continuously records the rhythm to be sure they are maintaining a normal rhythm. Studies show that 90% of patients have Atrial Fibrillation and don't know it.
So to Recap:
If you are in Atrial Fibrillation your doctor may want to schedule you for a procedure to get you back in the normal rhythm called an "Electrical Cardioversion."
This is considered a safe and low risk procedure. (Your risk will vary depending on the condition of your heart.)
The procedure is generally done as an outpatient and takes about 20 minutes to perform.
Electrical Cardioversion is used when your physician believes you will benefit from Rhythm Control.
I hope you've found this helpful.
Dr. Kirk Laman