Why use Internal Cardioversion?
There are several reasons why your doctor has recommended Internal Cardioversion for you.
Your doctor may believe that External Cardioversion may not have a high probability of working in you whereas Internal Cardioversion rarely fails. If you are overweight, then the probability of External Cardioversion working will decrease substantially as the energy will need to pass through a greater amount of tissue before it reaches the heart.
It may be that you have had External Cardioversion and it has not worked at all.
It may be that you are going to undergo another procedure such as an Electrophysiological Study which necessitates placing other catheters in your heart. Internal Cardioversion then requires only another one or two more catheters to be positioned by the side of other catheters already in position.
If your doctor believes that you may need several shocks then Internal Cardioversion may be preferred as External Cardioversion may leave skin burns, especially after multiple shocks.
External Cardioversion often requires an Anaesthetic to be administered. If your doctor believes that a General Anaesthetic would be detrimental to your health they may recommend Internal Cardioversion which often only requires a mild sedation.