2.2. CRT-D system

The Lumax 740 HF-T and its successor devices integrate the ICI-MF and Biotronik Home Monitoring® technology capable of automatic, daily transmissions of various parameters [16,17], including ICI data for investigational purposes. The ICI-MF has been market approved in Europe based on an extensive risk-benefit analysis. The benefit is currently merely hypothetical, and activation of the ICI-MF is therefore restricted to clinical trials.

While no additional material beyond standard CRT-D system needed to be implanted, the use of a true bipolar right ventricular (RV) defibrillation lead [18] and of a bipolar left ventricular (LV) lead with at least 15-mm distance between the tip and the ring electrodes is necessary for ICI-MF and was mandated by study protocol. This minimum distance was estimated based on the technical requirements needed to guarantee an adequate intracardiac impedance, given the exact measurement hardware and conditions. Originally, it was verified by numerical models but also proved to be appropriate in a previous study [15]. Right atrial and RV leads were implanted endocardially, and LV leads were implanted in a sidebranch of the coronary sinus.