Matschke Klaus, Pfeiffer Steffen, Mrowietz Christoph, Geisler Thomas, Tugtekin Sems M, Park Jai-Wun, Knaut Michael, Jung Friedrich
Department of Cardiac Surgery, Heart Center Dresden Ltd. University Hospital, Fetscherstr. 76, D-01307 Dresden, Germany.
Microvasc Res. 2005 Jul;70(1-2):97-101. doi: 10.1016/j.mvr.2005.04.006. Epub 2005 Jun 6.
The influence of heart rate on cardiac output, oxygen consumption, and myocardial activity has been widely investigated. However, the influence of heart rate on myocardial oxygen tension (pO2) remains unclear. Since the introduction of flexible pO2 micro catheters to measure partial oxygen tension in a working muscle, it is possible to investigate the influence of heart rate on myocardial oxygen tension.
Intraoperatively, a flexible pO2 micro catheter was positioned in the mid-myocardium of 8 male farm pigs. The heart rate was varied via an external pacer from base rate up to fibrillation and the corresponding myocardial pO2 was measured.
Within 2 min, the myocardial pO2 adjusted to a change in heart rate. In this animal model, an optimal myocardial pO2 was observed at 109 bpm. A further increase in heart rate led to a decrease in myocardial pO2. When the heart rate was reaching the level of a fibrillation, pO2 dropped to zero.
In young healthy pigs--with a normal blood vessel regulation and the pharmacologic and experimental conditions used in this study--a significant relation between myocardial pO2 and heart rate was observed. Myocardial oxygen tension increased during cardiac pacing until a heart rate of 109 bpm. Thereafter a decline of pO2 occurred. Each change in heart rate resulted in a corresponding change of pO2 within roughly 2 min.
心率对心输出量、氧消耗及心肌活动的影响已得到广泛研究。然而，心率对心肌氧分压（pO2）的影响仍不明确。自从引入用于测量工作肌肉中氧分压的柔性pO2微导管后，就有可能研究心率对心肌氧分压的影响。
术中，将一根柔性pO2微导管置于8只雄性农场猪的心肌中部。通过外部起搏器改变心率，从基础心率直至发生颤动，并测量相应的心肌pO2。
在2分钟内，心肌pO2随心率变化而调整。在该动物模型中，观察到心率为109次/分钟时心肌pO2最佳。心率进一步增加导致心肌pO2下降。当心率达到颤动水平时，pO2降至零。
在年轻健康猪中——在本研究中使用的正常血管调节以及药理和实验条件下——观察到心肌pO2与心率之间存在显著关系。心脏起搏期间心肌氧分压升高直至心率达到109次/分钟。此后pO2下降。心率的每次变化都会在大约2分钟内导致pO2相应变化。
