Geer M R, Wagner G S, Waxman M, Wallace A G
Am J Cardiol. 1977 May 4;39(5):684-9. doi: 10.1016/s0002-9149(77)80129-x.
Studies were performed to determine the chronotropic effect of acetylstrophanthidin during constant infusion through cannulation of the sinus nodal artery. Ten mongrel dogs weighing 13.5 to 18 kg were studied under sodium thiamylal anesthesia. Epicardial atrial and ventricular electrograms were recorded. The sinus nodal artery was cannulated and infused for 20 minutes at a rate of 2 cc/min with a solution containing acetylstrophanthidin, 0.5 microng/cc. Mean results for the group of 10 animals were determined. There was a gradual acceleration of the atrial rate of 45 beats/min after 6 to 8 minutes of infusion. The peak atrial rate of 175 beats/min was achieved by 10 to 12 minutes. This tachycardia persisted for 2 to 4 minutes without atrioventricular block or premature beats. By 12 to 14 minutes, there was a gradual slowing of atrial rate followed by bradycardia, sinus pauses and atrial arrest. Sinus nodal arterial infusion of acetylstrophanthidin produces an initial positive chronotropic effect and, if maintained, a depression of atrial rate and, terminally, atrial arrest. The gradual time course of development and decline of the tachycardia suggests that the "paroxysmal" atrial tachycardia caused by digitalis excess is the result of enhanced pacemaker automatically rather than reentry, and thus is not truly paroxysmal.
通过窦房结动脉插管持续输注毒毛花苷原期间，开展了多项研究以确定其变时作用。在硫喷妥钠麻醉下，对10只体重为13.5至18千克的杂种犬进行了研究。记录了心外膜心房和心室电图。通过窦房结动脉插管，以2毫升/分钟的速率输注含有毒毛花苷原（0.5微克/毫升）的溶液，持续20分钟。确定了10只动物组的平均结果。输注6至8分钟后，心房率逐渐加快45次/分钟。在10至12分钟时达到心房率峰值175次/分钟。这种心动过速持续2至4分钟，未出现房室传导阻滞或早搏。到12至14分钟时，心房率逐渐减慢，随后出现心动过缓、窦性停搏和心房停搏。通过窦房结动脉输注毒毛花苷原会产生最初的正性变时作用，如果持续输注，则会导致心房率降低，最终导致心房停搏。心动过速发展和消退的渐进时间过程表明，洋地黄过量引起的“阵发性”房性心动过速是起搏器自律性增强的结果，而非折返，因此并非真正的阵发性。
