1. From: Radiofrequency Catheter Ablation for Cardiac Tachyarrhythmias
Ann Intern Med. 1994;121(6): doi: /
Figure Legend:
Top.Bottom.Mechanism of atrioventricular (AV) nodal reentrant tachycardia. Two pathways constitute the circuit of this tachycardia; the α or slow pathway serves as the anterograde limb, and the β or fast pathway serves as the retrograde limb of the tachycardia circuit. Although both of these pathways were initially thought to be located within the AV node, they are apparently accessible to radiofrequency ablation techniques at locations outside the node. The slow pathway can be ablated successfully with the catheter positioned inferior and posterior to the AV node, whereas the fast pathway is located in an anterior and superior position. (CS = coronary sinus; RA = right atrium; RV = right ventricle; SA = sinoatrial) Mechanism of orthodromic atrioventricular (AV) reciprocating tachycardia observed in patients with the Wolff-Parkinson-White syndrome and in patients with concealed accessory pathways. The impulse travels down the AV node-His-Purkinje system, which constitutes the anterograde limb of the tachycardia, and returns to the atria through the accessory pathway (a left free-wall pathway here), which serves as the retrograde limb of the circuit. The accessory pathway is now accessible to the ablation catheter, which is positioned at the atrial or ventricular aspects of the tricuspid or mitral annuli. Delivery of radiofrequency energy through the catheter interrupts pathway conduction. (CS = coronary sinus; LA = left atrium; LV = left ventricle; SA = sinoatrial).
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