Nowak B, Fellmann P, Maertens S, Mols R, Demetz K, Brüls A, Geil S, Voigtländer T, Himmrich E, Meyer J
II. Medical Clinic, University Mainz, Germany.
Pacing Clin Electrophysiol. 1998 Nov;21(11 Pt 2):2232-5. doi: 10.1111/j.1540-8159.1998.tb01158.x.
An "Autosensing" algorithm available in SSI(R) and DDR(R) pacemakers automatically adapts the device's sensitivity to changing intracardiac signals. The atrial sensing function of this algorithm was tested for the first time with a VDD pacing system in which large variations of the atrial signal may occur because the atrial electrodes float in the atrial blood pool.
15 patients with a VDD pacing system were studied (Unity 292-07, lead 425; Sulzer Intermedics). The atrial sensing threshold was measured, and the atrial sensitivity was programmed with a 2:1 safety margin. The autosensing algorithm and sensitivity profile were temporarily activated, and an ambulatory ECG with continuous marker annotation was recorded. All patients underwent a 30-minute daily life activities protocol. A beat-to-beat analysis of the ambulatory ECG was correlated with the changes in atrial sensitivity.
The algorithm changed the baseline sensitivity from 0.57 +/- 0.23 mV during the test to 0.39 +/- 0.20 mV after the final rest period (P < 0.05). During the test 12.6 +/- 10.2 adaptations of the sensitivity occurred (range 0-33). In eight patients atrial undersensing occurred in 4.4% +/- 7.5% of the cycles (4-458 unsensed P waves). In these patients, the algorithm continuously adjusted the sensitivity towards more sensitive values, operating 19.1 +/- 18.3 changes compared with 5.4 +/- 7.3 changes in patients without undersensing (P = 0.009). Oversensing did not occur.
The autosensing algorithm effectively optimized atrial sensitivity in VDD pacing. In patients with atrial undersensing the algorithm continuously remained near the most sensitive settings, thus reacting as intended. A faster sensitivity adjustment of the system would be desirable.
SSI(R)和DDR(R)起搏器中可用的“自动感知”算法会自动使设备的灵敏度适应不断变化的心内信号。首次使用VDD起搏系统对该算法的心房感知功能进行了测试，在该系统中，由于心房电极漂浮于心房血池中，心房信号可能会发生很大变化。
研究了15例植入VDD起搏系统的患者（Unity 292 - 07，导线425；苏尔寿Intermedics）。测量心房感知阈值，并用2:1的安全裕度设置心房灵敏度。临时激活自动感知算法和灵敏度曲线，并记录带有连续标记注释的动态心电图。所有患者都进行了30分钟的日常生活活动方案。对动态心电图进行逐搏分析，并与心房灵敏度的变化相关联。
该算法将测试期间的基线灵敏度从0.57±0.23 mV改变为最后休息期后的0.39±0.20 mV（P < 0.05）。测试期间灵敏度发生了12.6±10.2次调整（范围为0 - 33次）。在8例患者中，心房感知不足发生在4.4%±7.5%的心动周期中（4 - 458个未感知的P波）。在这些患者中，该算法不断将灵敏度调整到更敏感的值，与无感知不足的患者相比，操作变化为19.1±18.3次，而无感知不足的患者为5.4±7.3次（P = 0.009）。未发生感知过度。
自动感知算法有效地优化了VDD起搏时的心房灵敏度。在有心房感知不足的患者中，该算法持续保持在最敏感的设置附近，从而按预期做出反应。该系统更快的灵敏度调整将是可取的。
