64 years old man implanted with a triple chamber defibrillator Concerto II CRT-D with positioning of a LV lead Medtronic 4195 in a small lateral vein; Complex implantation due to the small caliber of the veins + high threshold values + several stimulation sites with a phrenic nerve capture ;
During the interrogation of the device, it is essential to know the characteristics of the implanted material. Information about the patient and the implanted material (age, cardiologist, indication for implantation, models implanted leads…) are normally entered into the device at the time of implantation, but can be changed at any time. The Medtronic 4195 lead is unipolar. It is preferably used when the target vein is of very small caliber. On a triple chamber defibrillator, the only acceptable configuration is LV tip – RV ring but it is possible to test the lead in a LV tip – LV ring configuration. In this dependent patient, the stimulation is obviously inefficient because the lead is not bipolar but unipolar. As a result, this causes a temporary asystole during the test. On a triple pacemaker, it is possible to program a unipolar stimulation between the tip electrode and the can of the device (However, on a defibrillator, the ICD can cannot be part of the stimulation circuit).
