Anomalous extra nodal connections between atrium and ventricle along the AV groove are called accessory pathways. They can cause atrioventricular reentrant tachycardia (AVRT) Initial localisation of the accessory pathway is based on the delta wave and QRS morphology on surface ECG. Right sided and posteroseptal pathways are ablated using catheter positioned along the tricuspid annulus or the os of the coronary sinus. Locaction of left sided pathways are determined using catheter in coronary sinus, left atrium or left ventricle. Entry into the left atrium is trans septal using a septal puncture. Entry to the left ventricle can be anterogradely by a septal puncture or retrogradely through the aorta. Ablation along mitral annulus can be done using either the trans-septal or retrograde aortic approach. Trans-septal approach may be preferable in the elderly and in young children. Rarely left sided pathways can be ablated via the coronary sinus.
SVT ablation by retrograde approach
The picture shows catheter positions for ablation of left sided accessory pathways by the retrograde approach in the left anterior oblique (LAO) view. The ablation catheter is passed into the left ventricle through the femoral artery and the aorta. Surface ECG electrodes are marked by yellow arrows. The decapolar catheter is positioned in the coronary sinus and the quadripolar catheter is positioned in the region of the His bundle.