A CRT-P connected to a unipolar LV lead enable 2 unipolar configurations, including a) distal LV à can, and b) distal LV à RV ring. However, CRT-D enable only 1 configuration, i.e. distal LV à RV coil.
A CRT-P connected to a bipolar lead enables 1 bipolar (distal à proximal LV) and 3 unipolar configurations, including a) distal LV à can, b) distal LV à RV ring, and c) proximal LV à RV ring.
A CRT-D connected to a bipolar lead enables 1 bipolar (distal à proximal LV) and 2 unipolar configurations, including a) distal LV à RV coil and b) proximal LV à RV coil.
A CRT-P connected to a quadripolar lead enables 14 different configurations. From most distal to proximal, the 4 electrodes are Distal 1, Mid 2, Mid 3 and Proximal 4.
Dual site LV stimulation can be performed by selecting 2 LV stimulation vectors simultaneously.
Automated LV threshold
The automated measurement of the LV threshold in the ambulatory setting is programmable between every 8 to 24 h. The measurement is based on the sensing of the 1st derivative of the evoked response signal, which must be tested in order to adjust its sensitivity. When the automated adaptation has been activated, after every 8 to 24 h measurements, the delivered pulse amplitude is adapted with a programmable safety margin between 0.25 and 2.5 V (nominal = 1.0 V) without cycle-by-cycle verification of capture.