Vanoli E, De Ferrari G M, Stramba-Badiale M, Farber J P, Schwartz P J
Department of Physiology and Biophysics, University of Oklahoma.
Am Heart J. 1989 Feb;117(2):348-57. doi: 10.1016/0002-8703(89)90778-3.
Environmental studies suggested that exposure to carbon monoxide (CO) increases cardiovascular mortality among patients with coronary artery disease. We investigated whether, in dogs with a healed anterior myocardial infarction at low and high risk for ventricular fibrillation, acute exposure to CO has adverse effects during acute myocardial ischemia combined with exercise. One month after myocardial infarction, 17 dogs had ventricular fibrillation and 16 survived during the combined exercise and ischemia test. These tests were then repeated in all dogs with different concentrations of carboxyhemoglobin (COHb) (from 5% to 15%). With 15% COHb, heart rate (HR) at rest and during exercise was higher (p less than 0.05) than in the control tests. Surprisingly, the reflex HR response to acute ischemia was also altered; namely, the HR reduction characteristic of the low-risk animals was anticipated and accentuated (-31 +/- 25 versus 2 +/- 30 beats/min, p less than 0.05). Conversely, the HR increase characteristic of the high-risk group was reduced by CO (44 +/- 52 versus 72 +/- 43 beats/min, p less than 0.05). With 15% COHb, malignant arrhythmias occurred in two of the low-risk dogs and in none of the high-risk dogs. In the latter, CO was tested with a combination of exercise work load and myocardial ischemia duration not associated with ventricular fibrillation (VF) in the control condition. This study demonstrated that brief exposure to CO (1) profoundly alters the reflex HR response to exercise and to acute myocardial ischemia and (2) does not enhance the occurrence of malignant arrhythmias in conscious dogs with a healed myocardial infarction.
环境研究表明，接触一氧化碳（CO）会增加冠状动脉疾病患者的心血管死亡率。我们研究了在患有陈旧性前壁心肌梗死且有低、高心室颤动风险的犬类中，急性接触CO在急性心肌缺血合并运动期间是否具有不良影响。心肌梗死后1个月，17只犬在运动和缺血联合试验中发生心室颤动，16只存活。然后在所有犬类中使用不同浓度的碳氧血红蛋白（COHb）（从5%到15%）重复这些试验。当COHb为15%时，静息和运动时的心率（HR）高于对照试验（p<0.05）。令人惊讶的是，对急性缺血的反射性HR反应也发生了改变；也就是说，低风险动物典型的HR降低被提前并加重（-31±25对2±30次/分钟，p<0.05）。相反，高风险组典型的HR增加被CO降低（44±52对72±43次/分钟，p<0.05）。当COHb为15%时，两只低风险犬发生恶性心律失常，高风险犬无一发生。在后者中，CO是在对照条件下与不伴有心室颤动（VF）的运动负荷和心肌缺血持续时间相结合进行测试的。本研究表明，短暂接触CO（1）会深刻改变对运动和急性心肌缺血的反射性HR反应，（2）不会增加患有陈旧性心肌梗死的清醒犬类中恶性心律失常的发生。
