Improved cardiac cell excitation with symmetrical biphasic defibrillator waveforms.
Improved cardiac cell excitation with symmetrical biphasic defibrillator waveforms.
复制标题
通过对称双相除颤器波形改善心肌细胞兴奋。
DOI：
10.1152/ajpheart.1987.253.6.h1418
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
Balasky,G
中科院分区：
文献类型：
--
作者：
Jones,JL;Jones,RE;Balasky,G
根据最普遍接受的假设，室性除颤是通过刺激脑室临界质量中的细胞而产生的。对于单相除颤器波形，这一假设正确地预测了经胸小牛模型中的除颤阈值与培养细胞模型中细胞外场刺激的兴奋阈值之间的直接相关性。为了进一步验证这一假设，我们确定了对称双相波形是否降低了培养细胞模型中的兴奋阈值。对称双相波形将小牛的除颤阈值降低到相应单相波形的大约65%(14)。实验是在100到250微米的聚集体上进行的，这些聚集体来自10到12天的鸡胚。当细胞外钾(Ko)=6.5 mm，起搏间隔1000ms时，与相应的持续时间大于3ms的单相波形相比，对称双相矩形波的兴奋阈值强度-持续时间曲线明显减小。在流变区，双相和单相的阈值比为0.63(SE=0.02)。刺激过程中的跨膜电位显示，兴奋发生在双相波形的第二部分，强度低于单相波形的阈值。在短起搏间期(300ms)和高细胞外钾(10.5 mm)的“颤动条件”下，双相波形(5ms持续时间)的相对有效性增加。这些结果表明，在培养细胞模型中，对称的双相波形降低了激发阈值，并且阈值降低的程度取决于Ko和节拍频率。
According to the most commonly accepted hypothesis, ventricular defibrillation is produced by exciting cells in a critical mass of the ventricle. For monophasic defibrillator waveforms, this hypothesis correctly predicts a direct correlation between defibrillation threshold in the transthoracic calf model and excitation threshold for extracellular field stimulation in the cultured cell model. To further test the hypothesis, we determined whether symmetrical biphasic waveforms, which reduce defibrillation threshold in the calf to approximately 65% of that of the corresponding monophasic waveform (14), decrease excitation threshold in the cultured cell model. Experiments were performed on 100- to 250-microns aggregates from 10- to 12-day-old chick embryos. Excitation threshold strength-duration curves obtained at extracellular potassium (Ko) = 6.5 mM and pacing interval of 1,000 ms showed a significant reduction for symmetrical biphasic rectangular waveforms, when compared with the corresponding monophasic waveforms for durations greater than 3 ms. At the rheobase, the threshold ratio between the biphasic and monophasic waveforms was 0.63 (SE = 0.02). Transmembrane potentials during stimulation showed that excitation takes place during the second portion of the biphasic waveform for intensities that are subthreshold for the monophasic waveform. The relative effectiveness of the biphasic waveform (5-ms duration) increases under "fibrillation conditions" of short pacing interval (300 ms) and high extracellular potassium (10.5 mM). These results show that symmetrical biphasic waveforms decrease excitation threshold in the cultured cell model and that the degree of threshold reduction is dependent on Ko and beat rate.