每分通气量感知频率适应性起搏器Meta　Ⅱ－1204

Minute Ventilation Sensing Rate-adaptive Pacemaker meta Ⅱ-1204

目的：评价每分通气量感知频率适应性起搏器的生理性功能，简要介绍其工作原理。方法：５例患者埋植ＭｅｔａⅡ－１２０４型起搏器，术后程控为非频率适应性和频率适应性起搏方式，进行运动和干扰试验。结果：频率适应性起搏时运动起搏频率和心输出量分别较非频率适应性起搏增加５７％（１１０±１７比７０次／分）和４９％（１１．２±１．８比７．５±１．４Ｌ／ｍｉｎ），运动耐量则提高４０％（４５７±５５比３２４±４３秒）；频率适应启动时间为３６秒；摆动上肢加快起搏频率２３次／分（９３比７０次／分）。结论：ＭｅｔａⅡ－１２０４型起搏器可改善心动过缓者的运动耐量和心输出量，其起搏频率适应幅度与运动负荷相关性好，但频率适应速度较迟缓。

Objective :This study was conducted to assess the physiologic pacing functions of a new minute ventilation sensing rate-adaptive pacemaker (Meta Ⅱ-1204)w1th intreduction of its main working principle.Methods:Meta Ⅱ-1204 pacemakers were implanted in 5 patients (2 males and 3 females, mean age 57.6±8.4 years) with bradycardias. The pacemaker measures minute ventilation by sensing intravascular impedance using a standard bipolar electrode. After implantation, patients undement symptom limited semisupine bicycle exercise,and interference tests when the pacemaker was randomly programmed to fixed rate (VVI) and rate adaptive (VVIR) pacing modes, Pacing rate was recorded with Holter in both exercise.and interference tests;cardiac output and exercise capacity during exercise were measured.Results: Compared with exercise in VVI mtxle,the maxinial bicycle exercise pacing rate and cardiac output in VVIR mede were increatal,by 57%(110±17 vs.70bpm)and 49%(11.2±1.8 vs.7.5±1.4 L/min),respectively. Meanwhile exercise capacity was improved from 324±43 in VVI to 457±55 s (40%).The onset of rate response to exercise, was 36 s. continuous arm-swinging increased the pacing rate from a resting rate of 70 to 93 bpm.Conclusion : Meta Ⅱ-1204 pacemaker improves cardiac output and exercise capacity in patients with bradycardias. Although the onset of rate response is relatively slow,the increment of pacing rate is proportional to exercise workload.