Dohrmann M L, Goldschlager N F
Cardiol Clin. 1985 Nov;3(4):527-37.
Many factors affect the threshold for myocardial stimulation in patients with cardiac pacemakers. The acute local tissue reaction at the electrode-myocardium interface accounts for early threshold rises and may be minimized by choice of specific electrodes (steroid-eluting or carbon-tip). Physiologic variations due to changes in autonomic tone (including eating, sleeping, and exercise) account for day-to-day fluctuations in pacing threshold. Electrolyte and metabolic abnormalities, especially hyperkalemia, alkalosis, acidosis, and hyperglycemia, increase the pacing threshold. Commonly used antiarrhythmic drugs (quinidine and procainamide) also increase pacing threshold. Patients with pacemakers who require antiarrhythmic agents or who have coincident metabolic or electrolyte disturbances should be observed closely for failure to capture. Management of failure to capture is directed at removing the inciting cause and attempting to lower the pacing threshold with isoproterenol, if the situation is urgent. Acute increases in pacing threshold immediately following pacing system implantation can be treated with corticosteroids. Increasing the energy output of programmable pacemakers, in specific circumstances, or insertion of a temporary pacemaker capable of delivering higher energy output than the implanted generator may also be successful.
许多因素会影响心脏起搏器患者心肌刺激的阈值。电极 - 心肌界面处的急性局部组织反应会导致早期阈值升高，通过选择特定电极（类固醇洗脱电极或碳尖电极）可将其降至最低。自主神经张力变化（包括进食、睡眠和运动）引起的生理变化导致起搏阈值的日常波动。电解质和代谢异常，尤其是高钾血症、碱中毒、酸中毒和高血糖，会增加起搏阈值。常用的抗心律失常药物（奎尼丁和普鲁卡因酰胺）也会增加起搏阈值。需要抗心律失常药物或同时存在代谢或电解质紊乱的起搏器患者应密切观察是否出现夺获失败。对于夺获失败的处理是消除诱发原因，若情况紧急，可使用异丙肾上腺素试图降低起搏阈值。起搏系统植入后立即出现的起搏阈值急性升高可用皮质类固醇治疗。在特定情况下增加可编程起搏器的能量输出，或插入能够提供比植入式发生器更高能量输出的临时起搏器也可能成功。
