室上性心动过速60%以上是房室结折返性心动过速(AVNRT),发生机理主要是房室结内存在两条或两条以上传导速度不一的通道或单向传导阻滞构成的折返途径。由于折返途径循序不同,心动过速发作时可呈现两种不同形式,即所谓慢—快型和快—慢型。前者慢通道为前向支,快通道为逆向支,后者恰以相反的形式折返传导。它们反映在体表心电图和电生理检查也具有不同特点,有助于鉴别诊断。慢快型AVNRT:是成人最常见的PSVT,约90%的频率为140～200次/分。通常由一个房性或 More than 60% of supraventricular tachycardia is atrioventricular nodal reentrant tachycardia (AVNRT), the main mechanism is the occurrence of atrioventricular node in the presence of two or more channels of different conduction velocity or unidirectional block The way back Due to the different sequence of the turnaround, two different forms of tachycardia may occur, namely the so-called slow-fast type and fast-slow type. The former slow channel for the anterior branch, the fast channel for the reverse branch, the latter just the opposite form of reentry conduction. They are also reflected in the body surface ECG and electrophysiological examination also has different characteristics, contribute to the differential diagnosis. Slow type AVNRT: is the most common adult PSVT, about 90% of the frequency of 140 to 200 beats / min. Usually by atrial or