Tse H F, Lau C P, Leung S K, Leung Z, Mehta N
Department of Medicine, University of Hong Kong, Queen Mary Hospital, Hong Kong.
Pacing Clin Electrophysiol. 1996 Nov;19(11 Pt 2):1758-63. doi: 10.1111/j.1540-8159.1996.tb03219.x.
Single lead DDD pacing using unipolar or bipolar stimulation is limited by high atrial threshold. Overlapping biphasic (OLBI) waveform stimulation via atrial floating ring electrodes may preferentially enhance atrial pacing and avoid diaphragmatic pacing. Single lead DDD pacing with OLBI atrial pacing was studied in 12 patients (6 men and 6 women; mean age 74 +/- 7 years) with complete heart block. At implantation, atrial bipolar rings (area 27 mm2, separation 10 mm) were positioned at radiological defined high, mid, and low right atrial (RA) levels, and P wave amplitude and atrial and diaphragmatic pacing thresholds were determined in each position using unipolar, bipolar, and OLBI stimulation in random order. Although statistically insignificant, both the maximum and minimum sensed P wave amplitudes tended to be lower in the low RA position. Independent of the stimulation modes, minimum atrial pacing threshold occurred in the mid-RA. At mid-RA, the atrial pacing threshold was significantly lower with OLBI pacing compared with either unipolar or bipolar mode (3.9 +/- 2.2 V vs 6.7 +/- 3.5 V and 6.9 +/- 3.5 V, P < 0.05). Although the diaphragmatic thresholds were similar, OLBI pacing modes in the mid-RA and final location significantly improved the safety margin for avoidance of diaphragmatic pacing compared with unipolar mode. There was no correlation between atrial pacing and sensing threshold. At predischarge testing, all but one patient who developed atrial fibrillation had satisfactory atrial capture and a stable atrial pacing threshold (day 0: 2.6 +/- 1.1V vs day 2:3.2 +/- 1.3V, P = NS). However, diaphragmatic pacing occurred in four of 11 (36%) patients, especially in the upright position (sitting and standing). Our preliminary clinical results suggest that OLBI pacing via atrial floating ring electrodes can reduce the atrial pacing threshold. To optimize atrial pacing and sensing, the bipolar electrodes should be located at the mid-RA level first, although the high RA is an alternative. Despite significant improvements in the safety margin for diaphragmatic pacing with OLBI pacing, diaphragmatic stimulation remains a clinical problem.
使用单极或双极刺激的单导联DDD起搏受高心房阈值限制。通过心房漂浮环电极进行的重叠双相（OLBI）波形刺激可能会优先增强心房起搏并避免膈肌起搏。对12例（6例男性和6例女性；平均年龄74±7岁）完全性心脏传导阻滞患者进行了单导联DDD起搏联合OLBI心房起搏的研究。植入时，将心房双极环（面积27平方毫米，间距10毫米）置于放射学定义的右心房（RA）高、中、低水平，使用单极、双极和OLBI刺激以随机顺序在每个位置测定P波振幅以及心房和膈肌起搏阈值。尽管无统计学意义，但最低RA位置的最大和最小感知P波振幅往往较低。与刺激模式无关，最低心房起搏阈值出现在RA中部。在RA中部，与单极或双极模式相比，OLBI起搏时的心房起搏阈值显著更低（3.9±2.2伏 vs 6.7±3.5伏和6.9±3.5伏，P<0.05）。尽管膈肌阈值相似，但与单极模式相比，RA中部和最终位置的OLBI起搏模式显著提高了避免膈肌起搏的安全边际。心房起搏和感知阈值之间无相关性。在出院前测试中，除1例发生心房颤动的患者外，所有患者的心房捕捉均良好且心房起搏阈值稳定（第0天：2.6±1.1伏 vs 第2天：3.2±1.3伏，P=无显著性差异）。然而，11例患者中有4例（36%）出现膈肌起搏，尤其是在直立位（坐和站）。我们的初步临床结果表明，通过心房漂浮环电极进行OLBI起搏可降低心房起搏阈值。为优化心房起搏和感知，双极电极应首先置于RA中部水平，尽管RA较高位置也是一种选择。尽管OLBI起搏在膈肌起搏安全边际方面有显著改善，但膈肌刺激仍是一个临床问题。
