心房按需起搏后阈值变化的长期观察

Long term observation of thresholds on patients with atrial demand pacing

目的观察心房按需起搏（ＡＡＩ）后阈值变化的情况及其基本特征。方法对２０例ＡＡＩ起搏患者，在起搏后不同时间进行起搏阈值测定，并与同期收治的１０例心室按需起搏（ＶＶＩ）患者进行比较。结果ＡＡＩ起搏后不同时间的平均阈值较ＶＶＩ起搏后高０．２～０．８μＪ，第１周达高峰（２．１５±０．１５μＪ），２周时趋于平衡（１．７０±０．１６μＪ），随后速即转为稳定状态。心内电图Ｐ－Ｒ段抬高幅度与阈值呈负相关（ｒ＝－０．５１８６，Ｐ＜０．０５），低阈值组Ｐ－Ｒ段抬高幅度达０．２８±０．１２ｍＶ，显著高于高阈值组的０．１７±０．１０ｍＶ。结论ＡＡＩ起搏后的阈值在２周后即趋向稳定状态；心内电图Ｐ－Ｒ段抬高幅度对保证理想的阈值水平有重要临床意义。

Objective To investigate the basic features of threshold changes in patients with atrial demand pacing. Methods Thirty patients (20 cases of AAI and 10 cases of VVI pacing) were studied to assess the threshold changes during different durations after implanting the pacemaker.Results Comparing with the VVI group, the mean thresholds in the AAI group increased 0.2—0.8μJ and reached peak value (2.15±0 15μJ) at the first weekend after implanting the pacemaker and then tended toward stability (1.70±0.10μJ) after two weeks. There was a negative correlation between the elevation degree of P R segment and pacing thresholds ( r =-0.5168, P <0.05). The degree of P R elevation in the low threshold group was much higher than that in the high threshold group (0.28± 0.12mV vs 0.17±0.10mV). Conclusion Threshold tends toward stability two weeks after implanting the pacemaker. The elevation degree of P R segment has important clinical significance to assure ideal threshold level.