Chen S A, Chiang C E, Yang C J, Cheng C C, Wu T J, Wang S P, Chiang B N, Chang M S
Department of Medicine, Veterans General Hospital-Taipei, Taiwan, ROC.
Circulation. 1994 Sep;90(3):1262-78. doi: 10.1161/01.cir.90.3.1262.
Mechanisms and electropharmacological characteristics in adult patients with atrial tachycardia (AT) are not well described. We proposed that a combination of electropharmacological characteristics, recording of monophasic action potential, and effects of radiofrequency ablation could further determine the mechanisms and achieve a new classification in adults with various types of AT because they were important in regard to the correlation between mechanisms and pathophysiology, clinical syndrome, and responses to specific pharmacological or nonpharmacological therapies.
Thirty-six patients (11 female, 25 male; mean age, 57 +/- 13 years) with AT were referred for electropharmacological studies and radiofrequency ablation. Resetting response pattern, entrainment phenomenon, recording of monophasic action potential, serial drug test, response to Valsalva maneuver, endocardial mapping technique, and radiofrequency ablation were performed. Seven patients had automatic AT provocable with isoproterenol; neither initiation nor termination was related to programmed electrical stimulation. The other 29 patients had AT initiated or terminated by electrical stimulation and mechanisms related to triggered activity or reentry; nine of them needed isoproterenol to facilitate initiation of AT, associated with delayed afterdepolarization in monophasic action potential. All responded to adenosine (15 to 60 micrograms/kg) and Valsalva maneuver. Dipyridamole terminated AT and decreased the slope of afterdepolarization. Afterdepolarization was not found in the patients with automatic or reentrant AT. In 40 of 41 (98%), AT was ablated successfully, with late recurrence in 2 of 40 (5%) (follow-up, 18 +/- 4 months).
This study demonstrates the diverse mechanisms and electropharmacological characteristics of AT in adults. Furthermore, radiofrequency ablation of various types of AT could achieve high success and low recurrence rates.
成人房性心动过速（AT）的机制和电药理学特征尚未得到充分描述。我们提出，电药理学特征、单相动作电位记录以及射频消融的效果相结合，可以进一步确定机制，并对各种类型的成人AT进行新的分类，因为它们在机制与病理生理学、临床综合征以及对特定药物或非药物治疗的反应之间的相关性方面具有重要意义。
36例AT患者（11例女性，25例男性；平均年龄57±13岁）被转诊进行电药理学研究和射频消融。进行了重置反应模式、拖带现象、单相动作电位记录、系列药物试验、对瓦尔萨尔瓦动作的反应、心内膜标测技术以及射频消融。7例患者有可被异丙肾上腺素诱发的自律性AT；其起始和终止均与程控电刺激无关。另外29例患者的AT由电刺激起始或终止，机制与触发活动或折返有关；其中9例需要异丙肾上腺素来促进AT的起始，与单相动作电位中的延迟后除极相关。所有患者对腺苷（15至60微克/千克）和瓦尔萨尔瓦动作均有反应。双嘧达莫终止了AT并降低了后除极的斜率。在自律性或折返性AT患者中未发现后除极。41例患者中的40例（98%）AT被成功消融，40例中有2例（5%）出现晚期复发（随访18±4个月）。
本研究证明了成人AT的多种机制和电药理学特征。此外，各种类型AT的射频消融可获得高成功率和低复发率。
