温血心停跳液与冷晶体心停跳液对狗心率变异性的影响

为探讨体外循环（ＣＰＢ）导致心脏植物神经系统（ＣＡＳ）损伤的机理，了解温血心停跳液能否防止ＣＰＢ后心率变异性（ＨＲＶ）的降低，采用对照方法观察了温血心停跳液与冷晶体心停跳液对狗ＨＲＶ的影响。结果显示：ＣＰＢ后温血心停跳液组（ＷＢ组）和冷晶体心停跳液组（ＣＣ组）的全频谱（ＴＰ）、低频（ＬＦ）和高频（ＨＦ）均较术前明显降低（Ｐ＜０．０５），而且ＣＣ组比ＷＢ组降低更明显（Ｐ＜０．０５），但ＬＦ／ＨＦ在组内及组间均无明显变化（Ｐ＞０．０５）。ＣＰＢ后２４小时平均心率（ＭＨＲ）明显增加（Ｐ＜０．０５），且ＣＣ组高于ＷＢ组（Ｐ＜０．０５）。本研究表明：采用温血心停跳液或冷晶体心停跳液的ＣＰＢ不会干扰ＣＡＳ平衡，但均能使ＨＲＶ降低，温血心停跳液不能防止ＨＲＶ损害。

Effects of Warm Blood and Clod Crystalloid Cardioplegia on the Heart Rate Variability of Canine

The objectives of this study were to explore the mechanisms of cardiac autonomic system (CAS) impairment and to assess whether warm blood cardioplegia can prevent the decrease of heart rate variability (HRV) after CPB. Twelve adult mongrel dogs were divided into two groups. One group received warm blood cardioplegia and maintained at a systemic temperature of 38 throughout the experiment (WB group).The other received cold crystalloid cardioplegia at 31 and topical hypothermia(CC group).Anesthesia was induced and maintained with sodium pentobarbital and isoflurane. The heart was exposed through a right thoractomy. CPB was established using a single right atrial cannula.The arterial cannula was placed in the right femoral artery. The crossclamp time for both groups was 30 minutes. Serum potassium levels were normalized throughout the study. Each animals ECG was continuously recorded for 24 hours before surgery and for the first five postoperative days (POD) using a twochannel Holter monitor.The data were analyzed for heart rate variability (TP=total power, 0011.00;LF=low frequency,0.040.15; HF=high frequency,0.150.40; LF/HF). There were no differences in the preoperative values. In both groups the TP, LF, and HF decreased, compared to control (P<005), with CC group having significantly lower TP, LF and HF than the WB group (P<0.05). The LF/HF did not change both between groups and between before and after CPB in each group (P>0.05).The mean heart rate at 24 hours (MHR) increased in both groups, compared to control (P<0.05), with CC group having a significantly higher MHR than WB group (P<0.05). The data suggest that CPB, with warm blood or cold crystalliod cardioplegia does not disturb the balance of CAS, but it causes the decrease of HRV, and warm blood cardioplelgia can not prevent the impairment of HRV.