Jabbour Fouad, Horenstein Maria S., Grossman Shamai A.
SUNY Upstate University Hospital
CHOC (Children's Hospital of Orange County)
Atrioventricular reciprocating tachycardia (AVRT) is a type of supraventricular tachycardia (SVT) that requires specific electrophysiologic and electroanatomic characteristics. AVRT uses a circuit that consists of at least 2 different pathways with different electrical properties, including conduction velocity, refractory periods, and directionality. The anatomical substrate to sustain an AVRT can vary because AVRT may involve different configurations as follows: Two accessory pathways (APs) that enable communication between the atria and the ventricles. A single accessory pathway, in addition to the regular conduction system through the atrioventricular node, completes the circuit. Multiple accessory pathways through which the SVT can be perpetuated. . AVRT commonly starts with an ectopic atrial or ventricular beat that travels through one of the circuit's limbs due to the distinct electrical properties of the tissues involved. These properties allow the initiation and persistence of an SVT at a heart rate ranging from 150 to 250 bpm. AVRT is the most common type of arrhythmia associated with Wolff-Parkinson-White (WPW) syndrome. In this condition, antegrade conduction at rest occurs through an accessory pathway (or accessory pathways) that manifests on the surface electrocardiogram (ECG). The ECG shows a shortened PR interval followed by a delta wave or slurring of the initial portion of the QRS complex, which results in a widened QRS complex. AVRT can use an antegrade and non-decremental accessory pathway in these patients, and retrograde conduction can occur through the atrioventricular node or another accessory pathway. These patients can also develop accelerated conduction of atrial arrhythmias through the accessory pathway or accessory pathways that bypass the atrioventricular node. These preexcited atrial arrhythmias, especially atrial fibrillation, can be lethal due to rapid conduction into the ventricles. Permanent junctional reciprocating tachycardia is a rare type of AVRT, which uses the atrioventricular node as its antegrade limb and a decrementally conducting accessory pathway as its retrograde limb. This type of tachycardia typically has a slower heart rate, between 130 and 150 bpm, and is commonly refractory to medical management. Other unusual forms of AVRT use atrioventricular or nodoventricular accessory pathways, known as Mahaim pathways. These are decrementally conducting anomalous connections between the right atrium or the atrioventricular node and the right ventricle.
房室折返性心动过速（AVRT）是一种室上性心动过速（SVT），需要特定的电生理和电解剖学特征。AVRT利用一个由至少两条具有不同电特性的不同路径组成的环路，这些电特性包括传导速度、不应期和方向性。维持AVRT的解剖学基质可能不同，因为AVRT可能涉及以下不同的构型：两条使心房和心室之间能够通信的附加路径（APs）。除了通过房室结的正常传导系统外，一条附加路径完成环路。多条附加路径，室上性心动过速可通过这些路径持续存在。AVRT通常始于一个异位心房或心室搏动，由于所涉及组织的独特电特性，该搏动通过环路的一个分支传导。这些特性使得室上性心动过速能够在心率为150至250次/分钟的范围内起始和持续。AVRT是与预激综合征（WPW）相关的最常见的心律失常类型。在这种情况下，静息时的前传通过一条附加路径（或多条附加路径）发生，该附加路径在体表心电图（ECG）上表现出来。心电图显示PR间期缩短，随后是δ波或QRS波群起始部分的顿挫，这导致QRS波群增宽。在这些患者中，AVRT可利用一条前传且非递减的附加路径，并且逆传可通过房室结或另一条附加路径发生。这些患者还可通过绕过房室结的附加路径或多条附加路径发生房性心律失常的加速传导。这些预激性房性心律失常，尤其是心房颤动，由于快速传至心室可能是致命的。永久性交界性折返性心动过速是一种罕见的AVRT类型，它将房室结用作其前传分支，将一条递减传导的附加路径用作其后传分支。这种类型的心动过速通常心率较慢，在130至150次/分钟之间，并且通常对药物治疗无效。其他不常见的AVRT形式利用房室或结室附加路径，称为Mahaim路径。这些是右心房或房室结与右心室之间递减传导的异常连接。
