What is DC Cardioversion?

DC cardioversion is a procedure that is done to correct an irregular heartbeat (arrhythmia). An electric shock is delivered to the heart via a special machine.

How is this done?

Patients should not have eaten for at least 6 hours prior to the procedure. If DC cardioversion is performed for atrial fibrillation (the most common indication), the doctor should ensure that there is no clot in the heart. When the patient has atrial fibrillation, the chamber at the back of the heart (atrium) empties sluggishly into the main pump (left ventricle) of the heart. Blood in the atrium can then clot and cause a stroke when it dislodges. The food-pipe lies directly behind the atrium. In order to visualize this part of the heart the patient undergoes a transoesophageal echocardiogram ("seeing the heart through the food-pipe"), during which a special pipe is passed down the food-pipe. The patient’s throat is first deadened with a local anaesthetic spray. The pipe is connected to a cardiac ultrasound machine and gives a clear image of the heart.

If there is no clot in the heart, it is safe to proceed with DC cardioversion. The patient is connected to a cardiac monitor that shows the pattern and speed of the heartbeat. Once an intravenous drip has been placed in the arm, 2 large pads are placed on the front of the chest. One over the breastbone (sternum), and another below the left nipple. A short-acting drug is given into the drip. This medicine ensures that the patient is fast asleep before the electric shock is administered. The doctor places a paddle over each of the special pads on the chest. The amount of electricity delivered to the heart depends on the type of arrhythmia present.

The purpose of the shock is to restore a normal heartbeat. Once the paddles are charged with electricity, the doctor presses a button on each paddle at the same moment A shock is delivered to the heart. The patient may briefly experience some chest discomfort. Fortunately, patients have no recollection of the shock, because the medicine used for sedation also causes amnesia.

Following the test, most patients spend a few hours sleeping before the drug, given at the beginning of the test, wears off.

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