Syncope represents a relatively uncommon symptom of supraventricular tachycardia (SVT). It is likely that an impaired autonomic vasomotor response to the hemodynamic stress of tachycardia is the determinant of hemodynamic changes leading to cerebral hypoperfusion and syncope. In this regard, tilt-table test may detect abnormalities in the autonomic nervous function and predict the occurrence of syncope during SVT. Electrophysiology studies may reproduce the SVT, distinguish it from other life-threatening ventricular tachyarrhythmias, and exclude other causes of syncope. Not infrequently mixed syncope mechanisms are revealed during the above diagnostic workup raising doubts about the operating mechanism in the clinical setting. In such cases of uncertainty, an implantable loop recorder, providing long-term cardiac monitoring, may play a pivotal role in the establishment of the diagnosis, confirming the association of an arrhythmic event with the symptom. Herein, we present four such cases with recurrent unexplained syncope finally attributed to paroxysmal SVT guiding them to a potentially radical treatment through radiofrequency catheter ablation.

中文翻译：

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与室上性心动过速相关的晕厥：植入式环路记录器的诊断作用

晕厥是一种相对少见的室上性心动过速 (SVT) 症状。对心动过速的血流动力学应激的自主神经血管舒缩反应受损很可能是导致脑灌注不足和晕厥的血流动力学变化的决定因素。在这方面，倾斜台试验可以检测自主神经功能的异常并预测 SVT 期间晕厥的发生。电生理学研究可能会重现 SVT，将其与其他危及生命的室性快速性心律失常区分开来，并排除晕厥的其他原因。在上述诊断性检查中经常发现混合性晕厥机制，这引起了人们对临床环境中的操作机制的怀疑。在这种不确定的情况下，可植入循环记录器，提供长期心脏监测，可能在确定诊断、确认心律失常事件与症状的关联中起关键作用。在此，我们介绍了 4 例反复出现不明原因晕厥的病例，最终归因于阵发性 SVT，指导他们通过射频导管消融进行潜在的根治性治疗。