Liau C S, Chen M F, Lin F Y, Tsai C H, Lee Y T
Department of Internal Medicine, College of Medicine, National Taiwan University, Taipei, R.O.C.
J Electrocardiol. 1994 Apr;27(2):163-8. doi: 10.1016/s0022-0736(05)80100-1.
In treating atrial fibrillation (AF) the goal of ventricular rate reduction is still not determined. An animal model of AF was developed in which the relationship between ventricular rate and the parameters of cardiac function in AF can be studied. To simulate AF, complete heart block was chemically produced on open-chest dogs. Then, assisted by a portable computer, the ventricles were paced with a series of grossly irregular stimuli of predetermined rates, while atria were paced rapidly (500 beats/min). The resulting electrocardiogram and pressure were indistinguishable from the naturally occurring AF. It was found that in AF with ventricular rates that were lower than that of the control state, cardiac output was decreased. Cardiac output increased and reached a plateau when the ventricular rate increased to the level of the control state and then kept stable up to a rate of 320 beats/min. There was a discrepancy between the effective ventricular rate (rate of beats with pulse pressures > or = 25 mmHg in the femoral artery) and the electrical ventricular rate. When the electrical ventricular rate increased over the control ventricular rate the effective ventricular rate did not increase in a parallel manner. Rather, the effective ventricular rate leveled off at the control ventricular rate. This discrepancy may explain the parallel relationship between the effective ventricular rate and cardiac output.
在治疗心房颤动（AF）时，心室率降低的目标仍未确定。我们建立了一个AF动物模型，借此研究AF时心室率与心功能参数之间的关系。为模拟AF，在开胸犬身上通过化学方法造成完全性心脏传导阻滞。然后，在便携式计算机辅助下，用一系列预定频率的极不规则刺激对心室进行起搏，同时对心房进行快速起搏（500次/分钟）。由此产生的心电图和压力与自然发生的AF难以区分。结果发现，在心室率低于对照状态的AF中，心输出量降低。当心室率增加到对照状态水平时，心输出量增加并达到平台期，然后在高达320次/分钟的心率时保持稳定。有效心室率（股动脉脉压≥25 mmHg时的搏动频率）与电心室率之间存在差异。当电心室率超过对照心室率时，有效心室率并未以平行方式增加。相反，有效心室率在对照心室率水平趋于平稳。这种差异可能解释了有效心室率与心输出量之间的平行关系。
