Di Gregorio Franco, Marcantoni Lina, Mozzi Aldo, Barbetta Alberto, Zanon Francesco
Clinical Research Unit, Medico Spa, 35030 Rubano, PD, Italy.
Cardiology Department, Santa Maria della Misericordia GH, 45100 Rovigo, RO, Italy.
Bioengineering (Basel). 2025 Feb 17;12(2):194. doi: 10.3390/bioengineering12020194.
The pacing pulse produced by implantable stimulators can be described as a truncated exponential decay from the starting peak amplitude, corresponding to the discharge of the output stage capacitance (reservoir and isolation capacitors, in series) along the application time. Pulse decay and charge balancing have relevant implications on the ideal setting of a pacing device, as demonstrated by mathematical predictions based on well-acknowledged theoretical statements. Successful stimulation is achieved with minimum energy expense at a pulse duration shorter than the chronaxie time, which represents the upper border of the advisable duration interval. With any start amplitude, the stimulation safety margin can be improved by a duration increase beyond the chronaxie only up to an absolute limit (longest useful duration), which depends on the chronaxie and the pulse time-constant. At the longest useful duration, the threshold start amplitude is at the minimum and cannot decrease any further, though it and the corresponding pulse mean amplitude largely exceed the rheobase. The overall pacing performance is affected, in addition, by the load resistance and the electrode capacitance. Pulse amplitude decay limits the effectiveness of extended duration in implantable stimulators, making short pulses preferable whenever possible. Proper pulse settings based on actual waveform properties can prevent energy waste and reduce pacing consumption, thus prolonging the service life of the stimulator.
植入式刺激器产生的起搏脉冲可描述为从起始峰值幅度开始的截断指数衰减，这对应于输出级电容（串联的储能电容和隔离电容）在施加时间内的放电。如基于公认理论陈述的数学预测所示，脉冲衰减和电荷平衡对起搏设备的理想设置具有重要影响。在脉冲持续时间短于时值时间时，以最小的能量消耗实现成功刺激，时值时间代表了建议持续时间间隔的上限。对于任何起始幅度，仅在达到绝对极限（最长有效持续时间）之前，通过将持续时间增加到超过时值才能提高刺激安全裕度，该极限取决于时值和脉冲时间常数。在最长有效持续时间时，阈值起始幅度处于最小值且不能再降低，尽管它和相应的脉冲平均幅度大大超过基强度。此外，整体起搏性能还受负载电阻和电极电容的影响。脉冲幅度衰减限制了植入式刺激器中延长持续时间的有效性，因此尽可能采用短脉冲更可取。基于实际波形特性进行适当的脉冲设置可以防止能量浪费并减少起搏消耗，从而延长刺激器的使用寿命。
