Pacing parameters were stable at pre-discharge pacing check and latest follow-up of 8.5 ± 5 weeks (see Table 2 ).
Variations in pacing parameters between different poles may also be caused by varying levels of tissue fibrosis or scar.
Final LV lead position and pacing vector was determined at the discretion of the operator based upon pacing parameters, absence of PNS, and anatomic position.
Pacing parameters had improved at pre-discharge pacing check (threshold 1.75 V at 0.5 ms pulse width, impedance 510 Ω) and were better still at 6-week pacing check (threshold 1.25 V at 0.5 ms, impedance 540 Ω).
Optimization of CRT pacing parameters can further improve cardiac function, both acutely and chronically.
Moreover, in Section II of [2], a combined statistics of the residuals Y (i), see Eq. 11, and a set of pacing parameters are used to theoretically compute the performance limit of the decoder.
These RV pacing sites are readily identified and associated with stable lead position and reliable chronic pacing parameters (e.g., capture).
Problems with either PNS or unsatisfactory pacing parameters experienced during CRT may be resolved simply by changing the pacing configuration using this quadripolar lead system.
The Quartet lead was placed in a similar position to the discarded LV lead but satisfactory pacing parameters (threshold 0.75 V at 0.5 ms; impedance 740 Ω) and no PNS was found when pacing using the M3 M2 vector.
In these four difficult cases, the main determinant of LV lead position was a pacing configuration that gave the best pacing parameters (lowest capture threshold with good R-wave) without PNS.
The magnitude of %VP could be affected not only by the algorithmic property of MVP or Search AV+ but also by programming of several pacing parameters, ever-changing patient's conditions, and interactions of these components.
