By Dr. Afroze Ahmad, Las Sendas Cardiology, PC
This is the fourth and the final article in the four-article series on atrial fibrillation. In the previous three articles, we had discussed introduction to atrial fibrillation and several treatment options. This article deals with the electrical shock treatment of atrial fibrillation, also called cardioversion.
Imagine the heart as a house. Just like a house, the heart has both an electrical system or circuit and a plumbing system.
In the heart, the electrical circuit controls the rhythm and rate of the heartbeat. The electrical circuit also dictates that the flow of the current always occurs from top to bottom. As soon as a current is generated by the electrical circuit, and it flows from top to bottom, a heartbeat is created. This heartbeat causes the heart to contract or squeeze. The heart squeezes several times a minute. In a normal person, the heart squeezes from 60 to100 times a minute.
When there is chaos in the electrical circuit of the heart, an irregular rhythm, termed atrial fibrillation, may develop. During atrial fibrillation, the person may feel symptoms ranging from palpitations to passing out episodes. During atrial fibrillation, the heart rate may become very fast.
A fast and rapid heart rate, which is sustained for some time, is generally not well tolerated by both the heart and the body. In such cases, the electrical circuit of the heart has to be reset. Similarly, atrial fibrillation, if causing disabling symptoms or heart failure, also requires a resetting of the electrical system of the heart. This resetting of the electrical circuit of the heart is called cardioversion.
Cardioversion, or resetting of the electrical circuit of the heart, can be done both medically and electrically.
Medical cardioversion can be done with several medications on the market. It can be done in the office or in the hospital, depending on the type of medication used.
Electrical cardioversion, on the other hand, is always done in the hospital. A low energy shock is given, which triggers the heart to reset itself into the normal rhythm. Often, the doctor has to give more than one shock to restore the regular rhythm.
As we know from the previous articles, in atrial fibrillation, the heart does not pump, squeeze or contract adequately or completely. The heart quivers or fibrillates. When it quivers or fibrillates, it no longer empties completely. This remaining stagnant blood in the heart has a propensity to form clots. And it is the presence of these clots that increases the risk for stroke.
As the heart is shocked with current and reset, there is a chance blood clots residing in the heart may dislodge and travel to the brain. This, in turn, increases the risk for stroke. Therefore, generally, the cardiologist will provide adequate blood thinning medications for three to six weeks prior to the cardioversion.
At times, the cardiologist may also elect to look at your heart by having you swallow a soft flexible tube with a camera attached to it. The camera, from the stomach, may help the cardiologist look for blood clots prior to the cardioversion itself. This procedure is called a TEE. If clots are noted, the cardioversion is postponed for three to six weeks until the patient is adequately anticoagulated.
For cardioversion, the person prepares by not eating for approximately six to eight hours before the procedure. An intravenous tubing line is placed to give medications. The medications given include something that would make the person drowsy and fall asleep. Medication is given to allay any anxiety, which is both natural and expected. Once the person is well sedated, the cardiologist applies the shock to reset the heart. The patient wakes up with no recollection of the shock or events leading up to the shock.
The only evidence of the shock is the redness of the skin at the point of shock. This redness, which is not unlike sunburn, is something that would occur when spending a day at the beach. The person is monitored for a few hours, and then, generally, discharged to go home.
Cardioversion is well tolerated, and the complications, though present, are rare. The success rate of restoring a regular rhythm initially may exceed 70 percent. Many people may have to undergo repeat procedures. Generally, after two repeat procedures, the doctor and the patient sit down to discuss other options.