Maryland Heart Center

Electrophysiology Lab

ICD Firing

Your ICD is programmed to treat life- threatening fast heart rhythms. This therapy may be delivered by "pacing" your heart at a faster rate to try and break the rhythm or by shocking the heart out of the fast heart rhythm. The therapy delivered depends on the rate of the rhythm and certain other factors, called "discriminators". These "discriminators" help the ICD decide between upper chamber (atrial) arrhythmias and the life- threatening lower chamber (ventricular) arrhythmias. Sometimes the discriminators fail, and you may be shocked inappropriately. Therefore, it is important for us to "talk to" your ICD using a programmer and assess the functioning of the leads that pace and shock your heart. We can also look at the episode history to see how the ICD "read" the rhythm resulting in the shock to see if it was appropriate and to determine if changes need to be made to your therapy.

If you have symptoms of a rapid heart rate, your ICD may deliver therapy soon. In this event:

Stay calm and find a place to sit or lie down.
Ask someone to stay with you to notify for help if needed
If you feel fine after the shock, you do not need to seek medical attention. Be sure to contact us so we can arrange for a device interrogation.

When to contact your doctor:

If your symptoms of rapid heart rhythm last longer than a couple of minutes and cause lightheadedness, dizziness, or black-outs.
If your ICD fires more than once call 911. Do not drive yourself to the emergency room.
If you receive a shock and do not feel well afterwards, have someone call 911.
If you have a remote monitor, do an interrogation and call 410-328-6056.

Call 410-328-6056, if you have any further issues or questions or if you are unsure of what to do.

Please call if you would like to make an appointment or talk to someone about our services. Patients dial 1-866-408-6885, physicians dial 410-328-6622 or 1-800-318-1019.