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CARDIOTHORACIC SURGERY: Frequently Asked Questions about Internal Cardioverter Defibrillators
Questions frequently arise regarding internal cardioverter defibrillators (ICDs) during surgery. The problem is that cautery can be sometimes sensed as an arrhythmia and result in an inappropriate shock.
The best way to deal with an ICD during surgery is to temporarily inactivate it during the procedure. This is accomplished by simply placing a ring magnet over the device. During this time, the ICD will not sense ventricular tachyarrhythmias nor will it deliver therapy. There will be no interference with pacing function.
In an emergency situation, simply removing the magnet immediately restores full function and therapies. There is no delay looking for a programmer. I cannot emphasize enough that magnet application is the preferred method of temporarily inactivating an ICD.
For some procedures, possibly cardiac surgery, the ICD may have to inactivated by a programmer.
Now for the difficult part: Not all ICDs behave the same way.
The above is true for all Medtronic and St. Jude ICDs. If that is the case, just apply a magnet.
Another manufacturer, Guidant, has some devices that do not respond similarly.
I asked Guidant which models have and do not have magnet operations. They sent me the following information regarding ICD magnet operation by model:
Enable magnet use only is seen with models:
l Vitality 2 - T165/T167/T175/T177
l Vitality AVT - A135/A155
Change Tachy mode with magnet only:
l Ventak Mini/Mini II - 1740/41/42/43/45/46/62/63
l Ventak AV I/II/III DR - 1810/15/20/21/25/26
Enable magnet use and change tachy mode with magnet:
l Ventak Mini III/IV - 1782/83/86/88/89/90/93/96
l Ventak VR - 1774/1775
l Ventak AV III DR 1831/1836
l Ventak PRIZM I/II/AVT - 1850/51/52/53/57/58/60/61,1900
l Contak CD, CD2, Renewal - 1823, H115/119, H135/70/75/77/79
l Vitality DS/EL - T125/T135/T127
In my practice, most of my patients have Medtronic, thus there is little problem with these individuals.
If a patient has a Guidant, and there are any questions, call the manufacturer at 1-800-CARDIAC (1-800-227-3422) and ask for technical services for ICD.
They will provide information. Call the Guidant rep at the same number for assistance.
Now another issue: If a patient is referred for an elective procedure, the referring physician should provide the surgeon and the anesthesiologist information about the implanted device. In addition, the patient has been issued a card with the implant data.
In my opinion, elective cases should not be scheduled unless this information is known.
Cardiology fellows have been called at all hours to deactivate devices for elective cases, and when they ask what kind of device the patient has, there is no answer.
We will attempt to provide support when we can, but please help us.
Thank you for your cooperation.
Stephen C. Vlay, MD
Professor of Medicine
Director, Coronary Care Unit
[11/12/04]
