Kijtawornrat Anusak, Roche Brian M, Hamlin Robert L
QTest Labs, Columbus, OH, USA.
Comp Med. 2008 Oct;58(5):490-3.
Atrial fibrillation is a common arrhythmia with considerable morbidity and mortality. Limitations in studying both the mechanisms and therapy of atrial fibrillation arise due to the paucity of models that yield sufficiently high-quality data, are not costly, and in which atrial fibrillation is sustained long enough to make the necessary observations. The canine model we present is based on the hypothesis that atrial fibrillation requires heterogeneity of repolarization, that distribution of vagal fibers is heterogeneous in the atria, and that atrial fibrillation will persist after reflex stimulation of vagal efferents by increased systemic arterial pressure. Dogs were anesthetized with morphine-chloralose because this combination maintains nearly intact autonomic control. Systemic arterial pressure was elevated approximately 75 mm Hg during infusion of phenylephrine (2 microg/kg x min(-1)). The right atrium was paced for 20 min at 40 Hz. Atrial fibrillation was sustained after cessation of atrial pacing in dogs receiving phenylephrine, but terminated within seconds in normotensive animals. In conclusion, atrial fibrillation can be maintained for at least 40 min after cessation of rapid atrial pacing in dogs with phenylephrine-induced hypertension.
心房颤动是一种常见的心律失常，具有相当高的发病率和死亡率。由于缺乏能够产生足够高质量数据、成本不高且心房颤动持续时间足够长以便进行必要观察的模型，在研究心房颤动的机制和治疗方面存在局限性。我们提出的犬类模型基于这样的假设：心房颤动需要复极化的异质性，心房中迷走神经纤维的分布是异质的，并且在全身动脉压升高对迷走神经传出纤维进行反射性刺激后心房颤动将持续存在。使用吗啡 - 氯醛对犬进行麻醉，因为这种组合能维持几乎完整的自主神经控制。在输注去氧肾上腺素（2微克/千克×分钟⁻¹）期间，全身动脉压升高约75毫米汞柱。右心房以40赫兹起搏20分钟。接受去氧肾上腺素的犬在心房起搏停止后心房颤动持续存在，但在血压正常的动物中数秒内心房颤动就终止了。总之，在去氧肾上腺素诱导高血压的犬中，快速心房起搏停止后心房颤动可维持至少40分钟。
