Figure 5. A shows RAO projection of a left coronary artery angiogram performed prior to the laser ablation attempt and B the coronary sinus filling with dye. The thick arrow shows the orientation of the catheter towards the location of a left sided accessory atrioventricular pathway. 1 = angiographic catheter positioned in the aortic root, 2 = 4polar electrode catheter in the coronary sinus, 3 = bipolar electrode catheter in the right ventricle.