The SmartDelay function aims to allow optimization of the sensed AV delay, the paced AV delay, and the stimulated chamber (LV only or biventricular) based on reference tables stored in the device. This algorithm is based on the respective measurement of the right and left atrioventricular intervals on both spontaneous and paced atrium. The algorithm takes into account any programmed V-V delay. This “optimization” can be performed during a consultation with the programmer (in less than 2 minutes and 30 seconds) but is not automatically or repeatedly performed by the device in an outpatient setting.The stimulation threshold corresponds to the smallest electrical impulse, delivered outside all natural refractory periods, capable of generating the propagation of a depolarization. It can be measured in voltage (volts) or pulse width (milliseconds).