Left coronary angiogram (partially filled frame) showing PTCA (percutaneous transluminal coronary angioplasty) balloon positioned at a lesion in the obtuse marginal (OM) branch of the left circumflex coronary (LCX) artery. The vessel is underfilled possibly because of worsening of obstruction by the balloon. This balloon has a proximal and a distal radio-opaque marker. Some smaller balloons have only one radio-opaque marker in the middle. The check angio is taken to make sure that the balloon is positioned exactly across the lesion before inflation. The more radio opaque floppy end of the PTCA guide wire can be seen distally in the obtuse marginal branch. LAD: left anterior descending coronary artery. Catheter: guide catheter tip located within the left main coronary artery.