17 u00b1 8 mm arc at the vein ostium ivus allowed visualization of the ablation catheter such that it could be positioned ostially at the sites where atrial tissue was identified ablation was performed along 41 u00b1 13 of the pv ostium range 23 64 pv isolation as confirmed by loop catheter was demonstrated in 12 13 veins ivus can identify pv ostia and the sleeves of atrial tissue which are the targets for ablation this allows ablating close to the ostium and potentially limiting the area of lesion which may reduce the risk of pv stenosis ivus can thus be a useful adjunct in af ablation procedures anatomic muscle bundles identified in the coronary sinus cs in animal and necropsy studies may be responsible for preferential left to right atrial conduction ablation of these bundles are an important component of left atrial isolation for the treatment of atrial fibrillation it is therefore sought to identify these muscular bundles in vivo using intravascular ultrasound ivus an ivus 3 2 french 30 mhz catheter was inserted in the cs of 9 patients undergoing electrophysiologic studies manual pullback was performed and distal and proximal images were obtained well demarcated echogenic wall thickening in the cs corresponding to these muscular bands was found in all cases these bands were identified at the level of the.