Changes in heart rate variability in patients afte coronary artery bypass graft<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

汪正平  沈浩  左苏宁  裘毅敏  李士通
上海市第一人民医院麻醉科（200080）
WANG Zhengping, SHEN Hao, ZUO Suning, et al.Department of Anesthesiology, Shanghai First People's Hospital, Shanghai 200080
Chin J Anesthesiology, December 2000, Vol 20, No. 12

   ABSTRACT

Objective :To investigate the significance of the changes in heart rate variability (HRV) in patients undergoing coronary artery bypass graft procedure.
Methods: Thirty-six patients scheduled for elective coronary artery bypass were studied. HRV was monitored by HXD-I monitoring system one day prior to surgery (as baseline values), before anesthesia, at the end of surgery and on the 3rd day and 6th day after surgery.
Results: The baseline logical values for total power (TP),low frequency (LF), high frequency (HF), LF/HF ratio were 3.07±0.35，2.38±0.47，2.37±0.54 and 1.34±0.93 respectively, There were no significant changes in all these parameters before anesthesia as compared to baseline values. LF, HF and TP decreased significantly on the 3rd day after surgery as compared with baseline values, and were kept at the level on the 6th postoperative day.
Conclusions: The decrease in HRV power can last over 6 days after coronary bypass graft surgery, signifying reduced autonomous regulation of heart in the early postoperative days.
Key Words:Coronary artery bypass; Heart rate; Autonomic nervous system; Postoperative period

心率变异性（HRV）频谱分析能反映心脏的植物神经调节功能^[1] 。对判断心脏的功能状态和心血管疾病的转归有重要参考价值^[2-4]。近年来麻醉和手术对HRV影响的报道较多^[5，6]而有关冠脉搭桥术病人围术期HRV的变化国内外报道较少。虽有研究报道冠脉搭桥术病人术后心率变异性下降可持续数日到数周^[7，8]，但其观察的病例量有限，本文的目的是了解冠脉搭桥术病人HRV的变化及其意义。

　　　　　　　　　　　　　　    　资料和方法

　　冠脉搭桥术病人36例，其中男31例，女5例，年龄（62±10）岁，体重（67±11）kg，合并高血压18例、乳头肌功能不全17例、糖尿病7例、不稳定型心绞痛8例，劳力型心绞痛12例、陈旧性心肌梗塞室壁瘤形成11例，共行冠脉搭桥92支，其中8例加室壁瘤切除，3例加心脏瓣膜置换，1例加心肌桥切断，2例加激光心肌打孔术。研究其间病人无心律失常或仅有偶发心律失常。排除标准包括：术前服用洋地黄、充血性心力衰竭、3个月内心肌梗塞病史、房颤、已安置永久性心脏起搏器及植物神经功能失调。术后出现急性心肌梗塞表现或呼吸循环功能不稳定需要呼吸机支持或连续使用正性肌力药物3d以上或主动脉内球囊反搏的病人也予以排除。病人手术前正在服用的心血管用药继续至手术当日晨。
　　麻醉前30min肌注吗啡10mg，东莨菪碱0.3mg，病人入手术室后行心电图和脉搏血氧饱和度连续监测，在局麻醉 下开放上肢前臂外周静脉和桡动脉穿刺置管测量动脉压。麻醉诱导采用芬太尼、咪唑安定和哌库溴铵静脉注射，咪唑安定3～5mg分次注射后，缓慢注射芬太尼20μg/kg ,哌库溴铵 0.12mg/kg，根据病人血压情况再追加咪唑安定2～3mg，待血压平衡后行气管内插管控制呼吸。麻醉后行右侧颈内静脉脉穿刺，放置 7.5F CCO/SvO₂肺动脉漂浮导管，用Vigilance (Baxter公司，美国)和Datex 监测仪（芬兰）连续监测心排血量、混合静脉血氧饱和度、肺动脉压、中心静脉压及体循环和肺循环阻力等。麻醉维持间断静脉注射芬太尼、咪唑安定、哌库溴铵及吸入0.4～1%异氟醚。手术采用胸骨正中切口，在低温体外循环、心脏停搏状态下行冠状动脉-主动脉搭桥手术，采用自体大隐静脉搭桥。体外循环用Stockert Ⅲ型机器，人工肺采用Dedico或 Terumo 模式肺，预冲液采用乳酸林格氏液，聚明胶肽或琥珀酰明胶；全体外循环转流期间流量2.0～2.6.min^-1•m^-2，压力60~80mm Hg （1kPa=7.5 mmHg），血红蛋白浓度70~100g/l，停机后维持80g/L以上。心肌保护用氧合血低温停跳液主动脉根部灌注，用量15～20ml/kg，间隔20～30min灌注一次。体外循环停机后，循环功能用多巴胺和硝酸甘油调控，维持平均动脉压60～80mm Hg ，心排血量4L/min以上，体循环血管阻力略低于术前水平。术后保留气管导管入ICU，行人工通气支持6~12h后拔管。术后第2d开始进流质饮食，第3d开始下床活动。
　　HRV监测采用HXD-I型电脑多功能监测仪（华翔公司，哈尔滨），术前1d、麻醉前、手术结束时、以及术后第3d和6d于病人安静平卧10 min以上后分别记录15min连续心电图,术前和术后的心电图记录均在下午2～4点钟进行,以排队昼夜差别和进食的影响,并避免在应用镇痛镇静药2h内或心律失常发作期间记录.采集到的原始心电图采用频域分析法处理,观察HRV变化,每个采样段为256次无心律失常的连续心搏.本研究所观察的HRV总功率(TP)频段范围是0～0.5Hz,其中低频(LF)范围定义为0.09~0.4Hz,高频(HF)范围定义为0.15～0.39Hz。
　　HRV各功率指标均经对数转换后成正态分布，采用双因素方差分析进行统计学处理，P<0.05认为差异有显著性。

结　果<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

病人术中和术后循环功能基本平稳，术中体外循环转流平均128min，主动脉阻断95min，最低体温28.28℃±0.15℃。无一例病人正性肌力药物连续使用超过24h，部分病人用硝酸甘油静脉滴注控制血压，无术后心衰、心肌梗塞、严重心律失常等发生。术前1d的HRV总功率对数值为3.07±0.35，其中低频（LF）为2.38±0.47，高频（HF）为2.37±0.54，LF/HF比值为1.34±0.93。与术前比较，麻醉前HRV各指标无明显变化（P>0.05），手术结束时低、高频、总功率均有所下降，分别为2.18±0.45、2.22±0.60和2.90±0.37（P<0.05）。术后3d进一步下降，分别为1.70±0.65、1.86±0.65和2.63±0.41(P<0.05)。术后6d与术后3d基本维持在同一水平（P<0.05），见表1。

参　考　文　献
1． Malliani A. Pagani M, Lombardi F, et al. Cardiovascular neural regulation explored in the frequency domain. Circulation, 1991, 84:482-492.
2． Ewing DJ. Heart rate variability: an important new risk factor in patients following myocardial infarction. Clin Cardiol, 1991, 14: 683-685.
3． Kleiger RE, Miller JP, Bigger JT. Decreased heart rate variability and its association with increased mortality after acute myocardial infarction. Am J Cardiol, 1987, 59: 256-262.
4． Schwartz PJ, La Rovere MT, Vanoli E, Autonomic nervous system and sudden cardiac death: experimental basis and clinical observations for post-myocardial infarction risk stratification. Circulation, 1992, 85 (Suppl 1) I77-91.
5． Estafanous FG, Brum JM, Ribeiro MP, ET AL. analysis of heart rate variability to assess hemodynamic alterations following induction of anesthesia. J Cardiothorac Vasc Anesth, 1992, 6: 651-657.
6． Galletly DC, Westenberg AM, Robinson BJ, et al. Effect of halothane, isoflurane and fentanyl on spectral components of heart rate variability. Br J Anaesth, 1994, 72: 177-180.
7． Komatsu T, Kimura T, Nishiwaki K, ET AL. recovery of heart rate variability profile in patients after coronary artery surgery. Anesth Analg, 1997, 85: 713-718.
8． Hogue CW, Stein PK, Apostolido I. Alterations in temporal patterns of heart rate variability after coronary artery bypass graft surgery. Anesthesiology, 1994,81: 1356-1364.
9． Marlic M, Camm AJ. Components of heart rate variability: what they really mean and what we really measure. Am J Cardiol, 1993, 72: 821-822.
10． Ireland N, Meagher J, Sleigh JW, et al. Heart rate variability in patient recovering from general anaesthesia. Br J Anaesth, 1996;76: 657-662.
11． Heller PH, Perry F, Naifeh K. cardiovascular autonormic response during preoperative stress and postoperative pain. Pain, 1984, 18: 33-40.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />