Ohm O J, Skagseth E
Pacing Clin Electrophysiol. 1980 Mar;3(2):150-8. doi: 10.1111/j.1540-8159.1980.tb04323.x.
Thirty-three patients undergoing cardiac surgery in general hypothermia were investigated during temporary pacemaker treatment for changes in right ventricular electrogram amplitudes (AMAX, UMAX) and maximum derivatives (DMAX, SMAX) from pre-to postoperative phase (AMAX = amplitude of the part of the electrogram with highest mean maximum derivative (SMAX), DMAX = maximum derivative, UMAX = maximum amplitude deflection). Standard commercially available electrodes were used in 28 of the patients. A paired comparison (n = 29) showed a fall in AMAX from 8.64 +/- 0.91 mV (mean +/- SEM) preoperatively to 4.94 +/- 0.43 mV (p < 0.001) between the 4th and 6th postoperative day; UMAX dropped from 11.09 +/- 0.95 mV preoperatively to 5.44 +/- 0.42 mV (p < 0.000001) from the fourth to the sixth postoperative day. In the same period DMAX fell from 1.57 +/- 0.13 V/s to 0.67 +/- 0.05 V/s (p < 0.000001), and SMAX from 0.76 +/- 0.06 V/s to 0.32 +/- 0.02 V/s (p < 0.000001). The most marked fall in amplitudes and maximum derivatives occurred during the first 24 hours. A slight, but nonsignificant increase occurred in amplitudes and maximum derivatives from the 4th to 6th postoperative day until the electrodes were removed the 10th to 19th postoperative day. Amplitudes and maximum derivatives were of the same value in patients with aortic valve compared with coronary heart diseases in spite of a more deteriorated myocardial function in the former group. The changes in amplitudes and maximum derivatives followed the same pattern in the two groups from the pre- to postoperative phase. This indicates that the additional local hyperthermia applied to the patients undergoing valve surgery was of no importance in the electrogram changes. Despite the fact that the electrogram maximum derivative and maximum amplitude needed to inhibit a temporary pulse generator are of a low magnitude, the values found were so small that they might provoke demand failure. This actually occurred in four patients.
对33例在全身低温下进行心脏手术的患者，在临时起搏器治疗期间，研究其右心室心电图振幅（AMAX、UMAX）以及从术前到术后阶段最大导数（DMAX、SMAX）的变化（AMAX = 具有最高平均最大导数（SMAX）的心电图部分的振幅，DMAX = 最大导数，UMAX = 最大振幅偏移）。28例患者使用了标准的市售电极。配对比较（n = 29）显示，AMAX从术前的8.64±0.91 mV（平均值±标准误）降至术后第4天至第6天的4.94±0.43 mV（p < 0.001）；UMAX从术前的11.09±0.95 mV降至术后第4天至第6天的5.44±0.42 mV（p < 0.000001）。同期，DMAX从1.57±0.13 V/s降至0.67±0.05 V/s（p < 0.000001），SMAX从0.76±0.06 V/s降至0.32±0.02 V/s（p < 0.000001）。振幅和最大导数的最显著下降发生在最初24小时内。从术后第4天到第6天直至术后第10天至第19天电极移除，振幅和最大导数有轻微但不显著的增加。尽管主动脉瓣患者的心肌功能比冠心病患者更差，但两组患者的振幅和最大导数在术前到术后阶段遵循相同模式。这表明，对瓣膜手术患者施加的额外局部热疗对心电图变化无重要影响。尽管抑制临时脉冲发生器所需的心电图最大导数和最大振幅值较低，但所发现的值如此之小，以至于可能引发按需功能障碍。实际上有4例患者发生了这种情况。
