Internal Cardioversion
An internal cardioversion is an invasive cardiology interventional procedure used to correct the abnormal heart rhythm pattern of atrial fibrillation by applying a small electrical shock to your heart. It utilizes the techniques of cardiac catherization described above to deliver two specially made electrode catheters into your heart. A small electrical shock is created that often brings your heart back to a normal rhythm; you will receive general anesthesia before the shock is delivered. When the shock is delivered, the electrical current travels between the catheters inside your heart, interrupting your heart's abnormal rhythm and converting it to a regular rhythm. Your cardiologist monitors the affect this electrical current has on your heart rhythm and assesses whether the abnormal rhythm has been corrected. After a regular rhythm is restored, the catheters are removed and pressure held at the insertion sites for a short period of time. The procedure usually takes from 60 to 90 minutes.
The benefit of internal cardioversion is that, if successful, it restores normal heart rhythm, improving heart performance, lessening or relieving symptoms of atrial fibrillation and reducing the risk of subsequent blood clots and stroke. At the time of the procedure, 95 percent of patients experience a successful internal cardioversion. The effects of the procedure, even if successful, however, may not be permanent and the heart rhythm may return to atrial fibrillation.
Placement of the catheters into the heart and delivery of a shock does include some risk, including an abnormal heartbeat, infection, and injury at the entry site and possibly cardiac arrest. As with the standard external cardioversion, there is a small risk of a stroke or death.
Because atrial fibrillation increases your risk of developing blood clots, you will be placed on a blood thinner prior to the cardioversion. Coumadin (warfarin) is a blood thinner that reduces the risk of stroke by prolonging the time it takes blood to clot. You will take Coumadin for at least three weeks prior to the cardioversion. During this time you will need to have a blood test done at least once a week. This test is called a "protime" or an "INR," and it monitors the effectiveness of the Coumadin dose you are taking. The "INR" should be between 2.0 and 3.0 for three consecutive weeks before your cardioversion can be scheduled. You will be given instructions regarding your Coumadin in the day(s) before the procedure.
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