Mond H, Strathmore N, Kertes P, Hunt D, Baker G
Department of Cardiology, Royal Melbourne Hospital, Victoria, Australia.
Pacing Clin Electrophysiol. 1988 Nov;11(11 Pt 2):1866-74. doi: 10.1111/j.1540-8159.1988.tb06322.x.
Minute ventilation, the product of respiratory rate and tidal volume, correlates directly with oxygen consumption, cardiac output, and heart rate. An implantable pacemaker has been developed which allows variation in pacing rate in response to measured changes in minute ventilation. This single chamber system measures transthoracic impedance between the tip electrode of a standard bipolar lead and the pulse generator case. Low amplitude current pulses (1 mA for 15 microseconds) are generated each 50 msec between the the ring electrode and the case. In the adaptive mode, the pulse generator calculates a rate response factor or slope after maximal exercise. This slope, which describes the relationship between pacing rate and minute ventilation together with the pacing rate limits are the only programmable rate responsive features. Minute ventilation rate responsive systems have been implanted in 12 patients (8 females, 4 males), of mean age 63 years. Indications were His bundle ablation (6), acquired complete heart block (4), and sick sinus syndrome (2). At post-implant exercise testing, pacing rate rose within the first minute. Peak rate and time to upper rate were dependent on workload. After exercise, pacing rate remained at peak for up to 2 minutes before a gradual fall to resting rate. Comparative studies of the minute ventilation and the activity sensor pacing systems in the same patients confirmed that the minute ventilation system more closely parallels normal sinus response to activity. The minute ventilation rate responsive pacing system is simple to programme, no special lead is required and the system is highly physiologic.
分钟通气量是呼吸频率与潮气量的乘积，与氧耗量、心输出量和心率直接相关。现已开发出一种植入式起搏器，它可根据测得的分钟通气量变化来改变起搏频率。这种单腔系统测量标准双极导联尖端电极与脉冲发生器外壳之间的经胸阻抗。每隔50毫秒在环形电极与外壳之间产生低幅度电流脉冲（1毫安，持续15微秒）。在自适应模式下，脉冲发生器在最大运动后计算速率反应因子或斜率。该斜率描述了起搏频率与分钟通气量之间的关系，连同起搏频率限制是唯一可程控的频率反应特性。分钟通气量频率反应系统已植入12例患者（8例女性，4例男性），平均年龄63岁。适应证为希氏束消融术（6例）、获得性完全性心脏传导阻滞（4例）和病态窦房结综合征（2例）。植入后运动测试时，起搏频率在第一分钟内上升。峰值频率和达到上限频率的时间取决于工作量。运动后，起搏频率在峰值维持长达2分钟，然后逐渐降至静息频率。对同一患者的分钟通气量和活动传感器起搏系统的比较研究证实，分钟通气量系统更接近正常窦性心律对活动的反应。分钟通气量频率反应起搏系统编程简单，无需特殊导联，且该系统具有高度生理性。
