Azygous vein coil lowers defibrillation threshold in patients with high defibrillation threshold

Implantable cardioverter defibrillators (ICDs) reduce sudden death in patients at high risk. High defibrillation thresholds (DFTs) are not uncommon and may be the cause of failed defibrillation in patients with ICDs. Addition of a coil in the azygous vein posterior to the heart lowers the DFT in most patients by altering the electrical vector during defibrillation. This can be accomplished fairly easily and expeditiously using standard equipment in the laboratory. It also avoids the difficulties and complications associated with other methods such as the use of a subcutaneous array.

This series of three cases illustrates the type of patients who may benefit from this technique. The addition of an azygous coil successfully lowered the DFT to <10 J in each case. A brief description of the technique used to implant the azygous coil follows.

This simple and elegant solution can be highly useful as part of the armamentarium in tackling the problem of high DFTs.