Coronary sinus perforation is a relatively uncommon but much feared complication that may occur during the placement of left ventricular pacing lead. Coronary sinus perforation, especially in the presence of an obstructive flap, usually indicates the need to abandon the implantation attempt, as there are difficulties in crossing the obstructive flap as well as uncertainty of whether the lead is in the true lumen or into the pericardial space. We describe our experience in successfully placing the left ventricular lead safely despite the problems arising from these circumstances.