折返機制被認為是維持大多數(shù)快速性心律失常的基礎(chǔ)，見圖8-1。最典型的臨床折返環(huán)路模型為各種形式的心房撲動，涉及上或下腔靜脈、三尖瓣環(huán)等，因為環(huán)路周圍存在著結(jié)構(gòu)上的障礙。Wolff-Parkinson-White（W-P-W）預(yù)激綜合征中的束支折返和折返性快速性心律失常也起因于在解剖學(xué)上決定的路徑。發(fā)生于結(jié)構(gòu)性心臟疾病（例如缺血、梗死和心力衰竭）的許多形式的室性心動過速常常由解剖學(xué)上預(yù)先決定的折返路徑維持。心室浦肯野纖維網(wǎng)也被認為可提供結(jié)構(gòu)上的折返環(huán)路。反射是心室梗死時發(fā)生折返性期外收縮和部分室性二聯(lián)律的機制。第2位相折返被認為啟動了Brugada綜合征時心室纖維性顫動及心肌梗死急性期時室性心律失常。心房和心室纖維性顫動（發(fā)生于幾乎全部可遇見狀況，例如缺血、梗死、重塑、肥大和應(yīng)激反應(yīng)）主要由折返機制維持。多形性室性心動過速（尖端扭轉(zhuǎn)性）相關(guān)聯(lián)的各種類型QT綜合征也被認為由折返機制維持。

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