• Difference in the DFT with an azygos vein coil versus the standard SVC coil. [ Time Frame: Depented on recruitment ] [ Designated as safety issue: Yes ]
  

Patients undergoing placement of an ICD for the primary or secondary prevention of sudden cardiac death will be asked to participate. Patients will undergo implantation of a standard right ventricular ICD lead at the time of ICD implantation. In addition, patient will receive another high voltage ICD lead placed in the azygos vein as has been previously described in the literature (1). After sedating the patient, the DFT will be determined using a binary search algorithm. This consists of testing the device at a given output for the first shock after inducing VF. Should the shock fail, external defibrillation will be attempted, as is the standard method for performing DFT testing. As per the standard method of DFT testing, VF will be induced a second time, with the shock strength dependent on the success of the first shock. If the first shock was unsuccessful, the second will be at a higher output. If the first shock was successful, the second will be at a lower output. A third shock will then be delivered, based on the success or failure of the preceding shock to define the DFT. Of note, as the device can be programmed to give multiple shocks for one episode, VF will not necessarily need to be induced each time. For example, VF could be induced, and the device programmed to give a 20J shock followed by a 23J shock if not successful, thus limiting the number of VF inductions required. DFT testing will be done using both the standard configuration of high voltage leads as well as using the azygos lead. We hypothesize that using the azygos lead will result in a lower DFT.